The document reviews the potential use of remote sensing for investigating maize production. It discusses how the spectral reflectance characteristics of maize leaves can be used for classification and mapping of maize fields. Specifically, it describes how remote sensing can detect the spectral differences between soil and crop canopies, allowing for estimation of crop nutrient levels and health issues. The review concludes that remote sensing provides a fast, non-destructive method for monitoring biophysical and biochemical parameters of maize crops over large areas when appropriate sensors and processing techniques are used.
Effect of some abiotic factors on the concentration of β- sitosterol of Prunu...Innspub Net
Prunus africana is a medicinal plant which develops in the mountains of several African countries. β-sitosterol can be used as a marker for the control of the product quality of the aforementioned plant in terms of phytotherapy. Farmers and public authorities do not have information on the influence of altitude and chemical characteristics of soils on the concentration of β- sitosterol of P. africana. To contribute to solve the problem, this research, carried out in Cameroon, aims to appreciate the effect of abiotic factors on the above phenotypic character. In nine composite samples of barks taken at different altitudes, the
concentration of β-sitosterol is appreciated via qualitative analyses by Thin Layer Chromatography, High Performance Liquid Chromatography and quantitative analyses by Gas Chromatography coupled with the Mass Spectrometry. The chemical analyses of soils taken under the stems of the aforementioned trees were made. The statistics were carried out using the SAS software. The concentration of β-sitosterol in each population of P. africana varies from zero to 38.65 μg/ml. There is
variability between the averages of the aforementioned concentration with respect to altitude and chemical elements of the soils but the differences are not significant. The Ascending Hierarchical Clustering distributes populations into three groups. These
tools obtained are indispensable for the ground management, the products exploited from this tree species and the production of seeds for creating forest and agro-forest plantations.
The HortFlora Research Spectrum (HRS), is an international-peer reviewed, open access journal that serves as a forum for the exchange and dissemination of R & D advances and innovations in all facets of Horticultural Science (Pomology, Olericulture, Floriculture, Post Harvest Technology, Plant Biotechnology, and Medicinal & Aromatic Plants etc.) and its allied branches on an international level.
HRS is officially published quarterly (March, June, September and December) every year, in English (print & online version), under the keen auspices of Biosciences & Agriculture Advancement Society (BAAS), Meerut (India).
The journal is Indexed/Abstracted in
• Index Copernicus International, Poland with ICV: 27.39 • Ministry of Science & Higher Education, Poland with 02 points • Global Impact Factor with GIF 0.364• Indian Science Abstracts • CAB Abstracts • CABI Full text • CAB direct • ICRISAT-infoSAT • Google Scholar• CiteFactor • InfoBase Index with IBI Factor: 2.8 •New Journal Impact Factor (NJIF): 2.14 • ResearchBib • AgBiotech Net • Horticultural Science Abstracts • Forestry & Agroforestry Abstracts• Agric. Engg. Abstracts • Crop Physiology Abstracts • PGRs Abstracts • ResearchGate.net • getCited.com • Reference Repository • OAJI.net • Journal Index.net• University of Washington Library • University of Ottawa Library • Swedish University of Agric. Sci. Library, Stockholm, Sweden;
Full text PDF are available at: www.hortflorajournal.com
The present study aims to investigate the biodiversity of woody vegetation along a gradient of human impacting region in the three constituent parts of Ferlo Biosphere Reserve (FBR): the core area, the buffer zone and the transition area. We conducted an inventory of 110 plots of 900 m² each. Total species richness was 49 species distributed in 32 genera within 16 botanical families. The analysis of contesimal frequency showed that Guiera senegalensis is the most common species with a presence of 75% of such records. Examination of species abundance spectrum showed that four most abundant species such as Guiera senegalensis (29.5%), Combretum glutinosum (15.9%), Pterocarpus lucens (11.6%) and Boscia senegalensis (10 , 5%). These four species represent 68% of the total individuals of the RBF and are also the four most common species. The spectrum of abundance of families showed that Combretaceae is the best represented family with almost half of the number of species (49.7%). The representativeness of biological types and geographical affinity of the species has been established for the woody vegetation in the study area. The study of diversity indices revealed that the buffer zone and the transition area are subjected to multiple uses and experiencing human action. It has a greater diversity and a level of organization with higher timber stand than the central area which is an integral conservation zone.
Effect of some abiotic factors on the concentration of β- sitosterol of Prunu...Innspub Net
Prunus africana is a medicinal plant which develops in the mountains of several African countries. β-sitosterol can be used as a marker for the control of the product quality of the aforementioned plant in terms of phytotherapy. Farmers and public authorities do not have information on the influence of altitude and chemical characteristics of soils on the concentration of β- sitosterol of P. africana. To contribute to solve the problem, this research, carried out in Cameroon, aims to appreciate the effect of abiotic factors on the above phenotypic character. In nine composite samples of barks taken at different altitudes, the
concentration of β-sitosterol is appreciated via qualitative analyses by Thin Layer Chromatography, High Performance Liquid Chromatography and quantitative analyses by Gas Chromatography coupled with the Mass Spectrometry. The chemical analyses of soils taken under the stems of the aforementioned trees were made. The statistics were carried out using the SAS software. The concentration of β-sitosterol in each population of P. africana varies from zero to 38.65 μg/ml. There is
variability between the averages of the aforementioned concentration with respect to altitude and chemical elements of the soils but the differences are not significant. The Ascending Hierarchical Clustering distributes populations into three groups. These
tools obtained are indispensable for the ground management, the products exploited from this tree species and the production of seeds for creating forest and agro-forest plantations.
The HortFlora Research Spectrum (HRS), is an international-peer reviewed, open access journal that serves as a forum for the exchange and dissemination of R & D advances and innovations in all facets of Horticultural Science (Pomology, Olericulture, Floriculture, Post Harvest Technology, Plant Biotechnology, and Medicinal & Aromatic Plants etc.) and its allied branches on an international level.
HRS is officially published quarterly (March, June, September and December) every year, in English (print & online version), under the keen auspices of Biosciences & Agriculture Advancement Society (BAAS), Meerut (India).
The journal is Indexed/Abstracted in
• Index Copernicus International, Poland with ICV: 27.39 • Ministry of Science & Higher Education, Poland with 02 points • Global Impact Factor with GIF 0.364• Indian Science Abstracts • CAB Abstracts • CABI Full text • CAB direct • ICRISAT-infoSAT • Google Scholar• CiteFactor • InfoBase Index with IBI Factor: 2.8 •New Journal Impact Factor (NJIF): 2.14 • ResearchBib • AgBiotech Net • Horticultural Science Abstracts • Forestry & Agroforestry Abstracts• Agric. Engg. Abstracts • Crop Physiology Abstracts • PGRs Abstracts • ResearchGate.net • getCited.com • Reference Repository • OAJI.net • Journal Index.net• University of Washington Library • University of Ottawa Library • Swedish University of Agric. Sci. Library, Stockholm, Sweden;
Full text PDF are available at: www.hortflorajournal.com
The present study aims to investigate the biodiversity of woody vegetation along a gradient of human impacting region in the three constituent parts of Ferlo Biosphere Reserve (FBR): the core area, the buffer zone and the transition area. We conducted an inventory of 110 plots of 900 m² each. Total species richness was 49 species distributed in 32 genera within 16 botanical families. The analysis of contesimal frequency showed that Guiera senegalensis is the most common species with a presence of 75% of such records. Examination of species abundance spectrum showed that four most abundant species such as Guiera senegalensis (29.5%), Combretum glutinosum (15.9%), Pterocarpus lucens (11.6%) and Boscia senegalensis (10 , 5%). These four species represent 68% of the total individuals of the RBF and are also the four most common species. The spectrum of abundance of families showed that Combretaceae is the best represented family with almost half of the number of species (49.7%). The representativeness of biological types and geographical affinity of the species has been established for the woody vegetation in the study area. The study of diversity indices revealed that the buffer zone and the transition area are subjected to multiple uses and experiencing human action. It has a greater diversity and a level of organization with higher timber stand than the central area which is an integral conservation zone.
The significance of indigenous weather forecast knowledge and practices under...Premier Publishers
This paper discusses the implication of indigenous knowledge-based weather forecasts (IK-BFs) as a tool for reducing risks associated with weather variability and climate change among smallholder farmers on the south eastern slopes of Mount Kilimanjaro in Moshi Rural District of Tanzania. Participatory research approaches and household surveys were used to identify and document past and existing IK-BF practices. Local communities in the study transect use traditional experiences and knowledge to predict impending weather conditions by observing a combination of locally available indicators: plant phenology (40.80%), bird behaviour (21.33%), atmospheric changes (10.40%), insects’ behaviour (7.20%), environmental changes on Kilimanjaro, Pare and Ugweno mountains (4.80%), astronomical indicators (4.8%), animal behaviour (4.00%), water related indicators (3.73%) and traditional calendars (2.93%). The study established that 60% of farmers use and trust IK-BFs over modern science-based forecasts (SCFs). Although about 86.3% of respondents observed some correlation between IK-BFs and SCFs, and 93.6% supported integration of the two sets of information, the nature and extent of their correlation is not yet established. We none the less recommend that IK-BFs be taken into relevant national policies and development frameworks to facilitate agro-ecological conservation for use and delivery of effective weather and climate services to farming communities.
Land use Land Cover and Vegetation Analysis of Gujarat Science City Campus, A...ijtsrd
This paper illustrates the Land use Land cover detection and floral diversity of Gujarat science city campus, Ahmedabad, Gujarat, India. It is one of the science centers of the Gujarat state managed by the State Government. The initiation of this science center is to acknowledge students towards the science field. Arc GIS is used to detect the vegetation patches and analysis of Land use Land cover of the study area. The Unsupervised classification has been performed to analyze the study area. High resolution satellite image used for identifying the land use land cover classes. Out of which, the major area is covered by vegetation and constructed area. The major part is occupied by vegetation. The plant survey carried out in January 2020. The flora of campus consists of 73 species which belongs to 44 genera and 32 families. Herbs and shrubs were dominant as compared to the trees. Herbs were recorded with 15 species, while shrubs with 32 species, climbers with 10 species and trees with 11 species. These species were cultivated for ornamentation of the campus. Kruti Chaudhari | Nirmal Desai | Bharat. B. Maitreya "Land use Land Cover and Vegetation Analysis of Gujarat Science City Campus, Ahmedabad, Gujarat" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-4 , June 2020, URL: https://www.ijtsrd.com/papers/ijtsrd31232.pdf Paper Url :https://www.ijtsrd.com/biological-science/botany/31232/land-use-land-cover-and-vegetation-analysis-of-gujarat-science-city-campus-ahmedabad-gujarat/kruti-chaudhari
Paddy field classification with MODIS-terra multi-temporal image transformati...IJECEIAES
This paper presents the paddy field classification model using the approach based on periodic plant life cycle events and how these elevations in climate as well as habitat factors, such as elevation. The data used are MODIS-Terra two tiles of H28v09 and H29v09 of 2016, consist of 46 series of 8-daily data, with 500 meter resolution in Java region. The paddy field classification method based on the phenological model is done by Maximum Likelihood on the transformed annual multi-temporal image of the reflectance data, index data, and the combination of reflectance and index data. The results of the study showed that, with the reference of the Paddy Field Map from the Ministry of Agriculture (MoA), the overall accuracies of the paddy field classification results using the combination of reflectance and index data provide the highest (85.4%) among the reflectance data (83.5%) and index data (81.7%). The accuracy levels were varied; these depend on the slope and the types of paddy fields. Paddy fields on the slopes of 0-2% could be well identified by MODIS-Terra data, whereas it was difficult to identify the paddy fields on the slope >2%. Rain-fed lowland paddy field type has a lower user accuracy than irrigated paddy fields. This study also performed correlation (r2) between the analysis results and the statistical data based on district and provincial boundaries were >0.85 and >0.99 respectively. These correlations were much higher than the previous study results, which reached 0.49-0.65 (hilly-flat areas of county-level), and 0.80-0.88 (hilly-flat areas of provincial level) for China, and reached 0.44 for Indonesia.
Climatic variability and spatial distribution of herbaceous fodders in the Su...IJERA Editor
This study focused on future spatial distributions of Andropogon gayanus, Loxodera ledermanii and Alysicarpus
ovalifolius regarding bioclimatic variables in the Sudanian zone of Benin, particularly in the W Biosphere
Reserve (WBR). These species were selected according to their importance for animals feed and the
intensification of exploitation pressure induced change in their natural spatial distribution. Twenty (20)
bioclimatic variables were tested and variables with high auto-correlation values were eliminated. Then, we
retained seven climatic variables for the model. A MaxEnt (Maximum Entropy) method was used to identify all
climatic factors which determined the spatial distribution of the three species. Spatial distribution showed for
Andropogon gayanus, a regression of high area distribution in detriment of low and moderate areas. The same
trend was observed for Loxodera ledermannii spatial distribution. For Alysicarpus ovalifolius, currently area
with moderate and low distribution were the most represented but map showed in 2050 that area with high
distribution increased. We can deduce that without bioclimatic variables, others factors such as: biotic
interactions, dispersion constraints, anthropic pressure, human activities and another historic factor determined
spatial distribution of species. Modeling techniques that require only presence data are therefore extremely
valuable.
Floristic Composition, Structural Analysis and Socio-economic Importance of L...IJEAB
Floristic assessment plays a crucial role in managing and conserving phytodiversity. Thisstudy tried to determine the floristic composition, woody structure and socio-economic importance of the legume flora in the commune of Mayahi. We used plot method based on systematic sampling approach to inventory legume species within the parklands in September 2012. We recorded 55 legume species belonging to 24 genera in 56 relevés. Fabaceae is the dominant family among the legume botanical families in the parklands of the commune of Mayahi. The average woody legume density is 62 individuals per hectare in the commune of Mayahi. The woody legume species of highest average density are Faidherbia albida and Piliostigma reticulatum. While the total basal area of legumes of the commune is 1.12m2 / ha in the Mayahi commune. The crown cover varies according to the vegetation types but it is higher in the Goulbi N’kaba forest reserve. Legume flora provides a myriad of benefits to the people of Mayahi. The present study recommends furtherresearch that examines the impact of human activities on the legume flora of the parklands in the commune of Mayahi.
LAND USE /LAND COVER CLASSIFICATION AND CHANGE DETECTION USING GEOGRAPHICAL I...IAEME Publication
Land use and land cover change has become a central component in current strategies for managing natural resources and monitoring environmental changes. Geographical information system and image processing techniques used for the analysis of land use/land cover and change detection of Sukhana Basin of Aurangabad District, Maharashtra state. The tools used ArcGIS10.1 and ERDAS IMAGINE9.1, landsat images of 1996, 2003and 2014. From land use / land cover change detection it is found that during 1996-2014, water bodies cover have loss of 4 Sq. Km. Barren land have 146 Sq.Km. loss and forest area with 96 Sq.Km. loss. It is found that urbanization area has gain of 51 Sq.Km. and agricultural land cover also have gain of 195 Sq.Km.
A field experiment was conducted on at M.lekhe district (Ethiopia) during 2002 and 2003 years to investigate the response of tomato to rates of Nitrogen (N) and Phosphorus (P) fertilizers. The treatment consisted of factorial combination of four Nitrogen fertilizers rates (50 kg, 100 and 150 urea/ha) and four P rates (100,150 and 200 DAP/ha) arranged in a Randomized Complete Block Design. Statistically significant and highest yield per plant was recorded at the highest rate of DAP (200 kg/ha). The significantly lowest yield was found at the zero level (with out DAP applied). The marketable yield in Q/ha of the rates is 939.96, 822.44, 731.1067 and 421.44 for 200, 150, 100 and 0 rates respectively. As the partiual budget analisis showed increasing rate of phosphorus and urea fertilizers increased profitability until 200 kg/ha and 150 kg/ha respectively.
Agriculture plays a dominant role in economies of both developed and undeveloped countries. Agricultural remote sensing is not new, starts in back 1950s, but recent technological advances have made the benefits of remote sensing accessible to most agricultural producers. Pakistan is a country of different agro-climatic regions.
The soil is a major part of the natural environment and is vital to the existence of life on the planet.
Satellite imagery will provide the visible boundaries of soil types and a shallow penetration of soils.
Algorithm for detecting deforestation and forest degradation using vegetation...TELKOMNIKA JOURNAL
In forestry sector, the remote sensing technology hold a key role on forest inventory and
monitoring their changes. This paper describes the algorithm for detecting deforestation and forest
degradation using high resolution satellite imageries with knowledge-based approach. The main objective
of the study is to develop a practical technique for monitoring deforestation and forest degradation
occurred within the mangrove and swamp forest ecosystem. The SPOT 4, 5, and 6 images acquired in
2007, 2012 and 2014 were transformed into three vegetation indices, i.e., Normalized Difference
Vegetation Index (NDVI), Green-Normalized Difference Vegetation index (GNDVI) and Normalized
Green-Red Vegetation index (NRGI). The study found that deforestation was well detected and identified
using the NDVI and GNDVI, however the forest degradation could be well detected using NRGI, better
than NDVI and GNDVI. The study concludes that the strategy for monitoring deforestation, biomass-based
forest degradation as well as forest growth could be done by combining the use of NDVI, GNDVI and
NRGI respectively.
Effects of Water Deficiency on the Physiology and Yield of Three Maize GenotypesAgriculture Journal IJOEAR
Three maize genotypes research experiment was carried out in the experimental farm of University of Debrecen, Hungary. The genotypes were subjected to two different treatments, (irrigated and non-irrigated) where the irrigated was the control experiment. Physiological parameters (SPAD, LAI, HEIGHT) and grain yield (kg ha-1) were measured and statistically computed. From our results, SPAD, LAI and HEIGHT values were significantly affected by water stress in the three studied genotypes. Grain yield was reduced in two of the studied genotypes (S.Y Zephir and S.Y Chorintos). But no significant difference was notice in the KWS 4484 cultivar. LAI was not affected in the second measurement in the S.Y Chorintos genotype and, plant height did not record any difference in the first measurement in the KWS 4484 cultivar. Our results suggest second experiment to specifically look at the critical stage in the genotypes growth where water stress has the severe effect on the studied genotypes.
Effect of nitrogen fertilizer rates and intra-row spacing on yield and yield ...Premier Publishers
A field experiment was conducted at Gode Polytechnic College demonstration farm in 2013 under irrigation to observe the effect of six N rates (0, 46, 69, 92, 115 and 138 kg ha-1) and four intra-row spacing levels (7.5, 10 12.5 and 15 cm) on yield and yield components of onion (Allium cepa L.). The experiment was laid out according to randomized complete block design in factorial arrangement with three replications. Results of the analysis revealed that the interaction effects of N rates and intra-row spacing showed highly significant (P<0.01) effect on harvest index, fresh biomass yield, dry biomass yield, total bulb yield and marketable bulb yield. Thus, according to the result of partial Budget analysis application of 138kg N ha-1 planted at 7.5cm plant to plant distance was found the best treatment than others in relation to yield and yield components of onion under Gode condition.
Land Use / Land Cover Classification of kanniykumari Coast, Tamilnadu, India....IJERA Editor
The land use/ land cover details of Kanniyakuamri coast which is Located in the southern part of Tamil Nadu (India) is studied. Satellite imagery is used to identify the Land use/ Land cover status of the study area. The software like ERDAS and Arc GIS are used to demarcate the land use / Land cover features of Kanniyakuamari coast. Remote sensing and GIS provided consistent and accurate base line information than many of the conventional surveys employed for such a task. The total area of Kanniyakumari coast is 715 sq.km. The land use / land cover classes of the study area has been categorized into thirteen such as Plantation, Sandy area, Water logged area, Scrub forest, Crop Land, Water bodies, Land with scrub, Reserve forest, Land without Scrub, Salt area, Beach Ridge, Settlement and Fallow land on the basis NRSA Classifications. Among these categories, land with scrub land is predominantly found all over the study area, It is occupied about 336.36 sq.km (44.61 percent), Crop Land 273.82 sq.km(38.29 percent), water bodies lands sharing about 20.44 sq.km (2.85 percent ), settlement occupied with 6.96 sq.km (0.97 percent), and Fallow land was occupied 13.98 sq.km ( 1.95 percent ).
The significance of indigenous weather forecast knowledge and practices under...Premier Publishers
This paper discusses the implication of indigenous knowledge-based weather forecasts (IK-BFs) as a tool for reducing risks associated with weather variability and climate change among smallholder farmers on the south eastern slopes of Mount Kilimanjaro in Moshi Rural District of Tanzania. Participatory research approaches and household surveys were used to identify and document past and existing IK-BF practices. Local communities in the study transect use traditional experiences and knowledge to predict impending weather conditions by observing a combination of locally available indicators: plant phenology (40.80%), bird behaviour (21.33%), atmospheric changes (10.40%), insects’ behaviour (7.20%), environmental changes on Kilimanjaro, Pare and Ugweno mountains (4.80%), astronomical indicators (4.8%), animal behaviour (4.00%), water related indicators (3.73%) and traditional calendars (2.93%). The study established that 60% of farmers use and trust IK-BFs over modern science-based forecasts (SCFs). Although about 86.3% of respondents observed some correlation between IK-BFs and SCFs, and 93.6% supported integration of the two sets of information, the nature and extent of their correlation is not yet established. We none the less recommend that IK-BFs be taken into relevant national policies and development frameworks to facilitate agro-ecological conservation for use and delivery of effective weather and climate services to farming communities.
Land use Land Cover and Vegetation Analysis of Gujarat Science City Campus, A...ijtsrd
This paper illustrates the Land use Land cover detection and floral diversity of Gujarat science city campus, Ahmedabad, Gujarat, India. It is one of the science centers of the Gujarat state managed by the State Government. The initiation of this science center is to acknowledge students towards the science field. Arc GIS is used to detect the vegetation patches and analysis of Land use Land cover of the study area. The Unsupervised classification has been performed to analyze the study area. High resolution satellite image used for identifying the land use land cover classes. Out of which, the major area is covered by vegetation and constructed area. The major part is occupied by vegetation. The plant survey carried out in January 2020. The flora of campus consists of 73 species which belongs to 44 genera and 32 families. Herbs and shrubs were dominant as compared to the trees. Herbs were recorded with 15 species, while shrubs with 32 species, climbers with 10 species and trees with 11 species. These species were cultivated for ornamentation of the campus. Kruti Chaudhari | Nirmal Desai | Bharat. B. Maitreya "Land use Land Cover and Vegetation Analysis of Gujarat Science City Campus, Ahmedabad, Gujarat" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-4 , June 2020, URL: https://www.ijtsrd.com/papers/ijtsrd31232.pdf Paper Url :https://www.ijtsrd.com/biological-science/botany/31232/land-use-land-cover-and-vegetation-analysis-of-gujarat-science-city-campus-ahmedabad-gujarat/kruti-chaudhari
Paddy field classification with MODIS-terra multi-temporal image transformati...IJECEIAES
This paper presents the paddy field classification model using the approach based on periodic plant life cycle events and how these elevations in climate as well as habitat factors, such as elevation. The data used are MODIS-Terra two tiles of H28v09 and H29v09 of 2016, consist of 46 series of 8-daily data, with 500 meter resolution in Java region. The paddy field classification method based on the phenological model is done by Maximum Likelihood on the transformed annual multi-temporal image of the reflectance data, index data, and the combination of reflectance and index data. The results of the study showed that, with the reference of the Paddy Field Map from the Ministry of Agriculture (MoA), the overall accuracies of the paddy field classification results using the combination of reflectance and index data provide the highest (85.4%) among the reflectance data (83.5%) and index data (81.7%). The accuracy levels were varied; these depend on the slope and the types of paddy fields. Paddy fields on the slopes of 0-2% could be well identified by MODIS-Terra data, whereas it was difficult to identify the paddy fields on the slope >2%. Rain-fed lowland paddy field type has a lower user accuracy than irrigated paddy fields. This study also performed correlation (r2) between the analysis results and the statistical data based on district and provincial boundaries were >0.85 and >0.99 respectively. These correlations were much higher than the previous study results, which reached 0.49-0.65 (hilly-flat areas of county-level), and 0.80-0.88 (hilly-flat areas of provincial level) for China, and reached 0.44 for Indonesia.
Climatic variability and spatial distribution of herbaceous fodders in the Su...IJERA Editor
This study focused on future spatial distributions of Andropogon gayanus, Loxodera ledermanii and Alysicarpus
ovalifolius regarding bioclimatic variables in the Sudanian zone of Benin, particularly in the W Biosphere
Reserve (WBR). These species were selected according to their importance for animals feed and the
intensification of exploitation pressure induced change in their natural spatial distribution. Twenty (20)
bioclimatic variables were tested and variables with high auto-correlation values were eliminated. Then, we
retained seven climatic variables for the model. A MaxEnt (Maximum Entropy) method was used to identify all
climatic factors which determined the spatial distribution of the three species. Spatial distribution showed for
Andropogon gayanus, a regression of high area distribution in detriment of low and moderate areas. The same
trend was observed for Loxodera ledermannii spatial distribution. For Alysicarpus ovalifolius, currently area
with moderate and low distribution were the most represented but map showed in 2050 that area with high
distribution increased. We can deduce that without bioclimatic variables, others factors such as: biotic
interactions, dispersion constraints, anthropic pressure, human activities and another historic factor determined
spatial distribution of species. Modeling techniques that require only presence data are therefore extremely
valuable.
Floristic Composition, Structural Analysis and Socio-economic Importance of L...IJEAB
Floristic assessment plays a crucial role in managing and conserving phytodiversity. Thisstudy tried to determine the floristic composition, woody structure and socio-economic importance of the legume flora in the commune of Mayahi. We used plot method based on systematic sampling approach to inventory legume species within the parklands in September 2012. We recorded 55 legume species belonging to 24 genera in 56 relevés. Fabaceae is the dominant family among the legume botanical families in the parklands of the commune of Mayahi. The average woody legume density is 62 individuals per hectare in the commune of Mayahi. The woody legume species of highest average density are Faidherbia albida and Piliostigma reticulatum. While the total basal area of legumes of the commune is 1.12m2 / ha in the Mayahi commune. The crown cover varies according to the vegetation types but it is higher in the Goulbi N’kaba forest reserve. Legume flora provides a myriad of benefits to the people of Mayahi. The present study recommends furtherresearch that examines the impact of human activities on the legume flora of the parklands in the commune of Mayahi.
LAND USE /LAND COVER CLASSIFICATION AND CHANGE DETECTION USING GEOGRAPHICAL I...IAEME Publication
Land use and land cover change has become a central component in current strategies for managing natural resources and monitoring environmental changes. Geographical information system and image processing techniques used for the analysis of land use/land cover and change detection of Sukhana Basin of Aurangabad District, Maharashtra state. The tools used ArcGIS10.1 and ERDAS IMAGINE9.1, landsat images of 1996, 2003and 2014. From land use / land cover change detection it is found that during 1996-2014, water bodies cover have loss of 4 Sq. Km. Barren land have 146 Sq.Km. loss and forest area with 96 Sq.Km. loss. It is found that urbanization area has gain of 51 Sq.Km. and agricultural land cover also have gain of 195 Sq.Km.
A field experiment was conducted on at M.lekhe district (Ethiopia) during 2002 and 2003 years to investigate the response of tomato to rates of Nitrogen (N) and Phosphorus (P) fertilizers. The treatment consisted of factorial combination of four Nitrogen fertilizers rates (50 kg, 100 and 150 urea/ha) and four P rates (100,150 and 200 DAP/ha) arranged in a Randomized Complete Block Design. Statistically significant and highest yield per plant was recorded at the highest rate of DAP (200 kg/ha). The significantly lowest yield was found at the zero level (with out DAP applied). The marketable yield in Q/ha of the rates is 939.96, 822.44, 731.1067 and 421.44 for 200, 150, 100 and 0 rates respectively. As the partiual budget analisis showed increasing rate of phosphorus and urea fertilizers increased profitability until 200 kg/ha and 150 kg/ha respectively.
Agriculture plays a dominant role in economies of both developed and undeveloped countries. Agricultural remote sensing is not new, starts in back 1950s, but recent technological advances have made the benefits of remote sensing accessible to most agricultural producers. Pakistan is a country of different agro-climatic regions.
The soil is a major part of the natural environment and is vital to the existence of life on the planet.
Satellite imagery will provide the visible boundaries of soil types and a shallow penetration of soils.
Algorithm for detecting deforestation and forest degradation using vegetation...TELKOMNIKA JOURNAL
In forestry sector, the remote sensing technology hold a key role on forest inventory and
monitoring their changes. This paper describes the algorithm for detecting deforestation and forest
degradation using high resolution satellite imageries with knowledge-based approach. The main objective
of the study is to develop a practical technique for monitoring deforestation and forest degradation
occurred within the mangrove and swamp forest ecosystem. The SPOT 4, 5, and 6 images acquired in
2007, 2012 and 2014 were transformed into three vegetation indices, i.e., Normalized Difference
Vegetation Index (NDVI), Green-Normalized Difference Vegetation index (GNDVI) and Normalized
Green-Red Vegetation index (NRGI). The study found that deforestation was well detected and identified
using the NDVI and GNDVI, however the forest degradation could be well detected using NRGI, better
than NDVI and GNDVI. The study concludes that the strategy for monitoring deforestation, biomass-based
forest degradation as well as forest growth could be done by combining the use of NDVI, GNDVI and
NRGI respectively.
Effects of Water Deficiency on the Physiology and Yield of Three Maize GenotypesAgriculture Journal IJOEAR
Three maize genotypes research experiment was carried out in the experimental farm of University of Debrecen, Hungary. The genotypes were subjected to two different treatments, (irrigated and non-irrigated) where the irrigated was the control experiment. Physiological parameters (SPAD, LAI, HEIGHT) and grain yield (kg ha-1) were measured and statistically computed. From our results, SPAD, LAI and HEIGHT values were significantly affected by water stress in the three studied genotypes. Grain yield was reduced in two of the studied genotypes (S.Y Zephir and S.Y Chorintos). But no significant difference was notice in the KWS 4484 cultivar. LAI was not affected in the second measurement in the S.Y Chorintos genotype and, plant height did not record any difference in the first measurement in the KWS 4484 cultivar. Our results suggest second experiment to specifically look at the critical stage in the genotypes growth where water stress has the severe effect on the studied genotypes.
Effect of nitrogen fertilizer rates and intra-row spacing on yield and yield ...Premier Publishers
A field experiment was conducted at Gode Polytechnic College demonstration farm in 2013 under irrigation to observe the effect of six N rates (0, 46, 69, 92, 115 and 138 kg ha-1) and four intra-row spacing levels (7.5, 10 12.5 and 15 cm) on yield and yield components of onion (Allium cepa L.). The experiment was laid out according to randomized complete block design in factorial arrangement with three replications. Results of the analysis revealed that the interaction effects of N rates and intra-row spacing showed highly significant (P<0.01) effect on harvest index, fresh biomass yield, dry biomass yield, total bulb yield and marketable bulb yield. Thus, according to the result of partial Budget analysis application of 138kg N ha-1 planted at 7.5cm plant to plant distance was found the best treatment than others in relation to yield and yield components of onion under Gode condition.
Land Use / Land Cover Classification of kanniykumari Coast, Tamilnadu, India....IJERA Editor
The land use/ land cover details of Kanniyakuamri coast which is Located in the southern part of Tamil Nadu (India) is studied. Satellite imagery is used to identify the Land use/ Land cover status of the study area. The software like ERDAS and Arc GIS are used to demarcate the land use / Land cover features of Kanniyakuamari coast. Remote sensing and GIS provided consistent and accurate base line information than many of the conventional surveys employed for such a task. The total area of Kanniyakumari coast is 715 sq.km. The land use / land cover classes of the study area has been categorized into thirteen such as Plantation, Sandy area, Water logged area, Scrub forest, Crop Land, Water bodies, Land with scrub, Reserve forest, Land without Scrub, Salt area, Beach Ridge, Settlement and Fallow land on the basis NRSA Classifications. Among these categories, land with scrub land is predominantly found all over the study area, It is occupied about 336.36 sq.km (44.61 percent), Crop Land 273.82 sq.km(38.29 percent), water bodies lands sharing about 20.44 sq.km (2.85 percent ), settlement occupied with 6.96 sq.km (0.97 percent), and Fallow land was occupied 13.98 sq.km ( 1.95 percent ).
Characterization of Diatraea saccharalis in Sugarcane (Saccharum officinarum)...Agriculture Journal IJOEAR
Abstract— Applications of remote sensing in agriculture have increased in recent years, especially for the development of sensors with better spatial and spectral resolutions. The objective of this study was to assess and evaluate the spatial and spectral variability of infection Diatraea saccharalis of sugarcane (Saccharum officinarum) through optical sensors in the Huasteca, Mexico. The methodology consisted in to make in situ measurements with a hyperspectral spectroradiometer in areas with and without apparent damage by the plague. For spatial and scaling representation Landsat 8 images were used. The data obtained in the field showed the spectral behavior of the plague; and the space-spectral reflectance variation was made by visibles and infrared bands for the vegetation. This process is an important approach to take a look from the geographical point of view to the problems related to the risk assessment of plague and diseases, their incidence, spread and severity, as well as support for sampling and monitoring activities. The used of these technologies provides advantages in research and in the implementation of precision farming techniques.
Crop Identification Using Unsuperviesd ISODATA and K-Means from Multispectral...IJERA Editor
Agriculture is one of the oldest economic practice of human civilization is indeed undergoing a makeover. Remote sensing has played a significant role in crop classification, crop health and yield assessment. Hyper spectral remote sensing has also helped to enhance more detailed analysis of crop classification. This paper focuses the unsupervised classification methods i.e k-means and ISODATA for the crop identification from the remote sensing image.The experimental analysis is perfomed using ENVI tool. The color composite mappings associated with the image is also studied.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Ecological environment effects on germination and seedling morphology in Park...AI Publications
Néré (Parkia biglobosa) is a wild species preferred and overexploited for its multiple uses by rural populations in Sub-Saharan Africa. The study of its germination and seedlings could constitute a prerequisite for its domestication, necessary for its conservation. This study aimed to assess the germination and morphology of seedlings taking into account distinct habitats from its natural environment.A total of 2160 seeds from different mother plants and 540 seedlings from germination were selected and evaluated. The trials were conducted on three sites (two nurseries in Côte d'Ivoire vs one greenhouse in France) with different microclimates. The results showed that the larger the mother trees are, the larger the seeds they produce, which in turn generate more vigorous seedlings. This study showed that the species grows better in a milder environment that is different from its region of origin (fertile soil with a stable or humid tropical climate: Montpellier greenhouse and Daloa nursery). Overall, parent trees did not statistically influence each germination and seedling development parameter for the three sites combined (P > 0.05). However, analysis of variance showed that germination and seedling development parameters differed between experimental sites (P < 0.05). These results are useful and could be used as decision support tools to guide conservation (domestication) and agroforestry programmes based on Parkia biglobosa. This study could be extended to other endangered species in order to preserve biodiversity.
Influence of fertilizers on incidence and severity of early blight and late b...Innspub Net
The potato (Solanum tuberosum) production in the Far North Region, Cameroon is confronted with, diseases and pests. To improve the production of this plant, a study was carried out in Mouvou and Gouria to evaluate the impact of fertilizers on the development of late blight and early blight diseases of this plant. The experimental design used was a completely randomized block with 4 treatments: Mycorrhizae (MYC), NPK (20-10-10) chemical fertilizers, chicken droppings (CD) and a control (T). The plant material used was a local variety of potato (Dosa). Disease incidence and severity and rainfall were evaluated. Area Under Disease Progress Curve was calculated. At 60 DAS, mean incidences recorded for fertilizers were 5.7, 3.6, 1.8 and 0.8 % respectively for control, MYC, NPK and CD. In general, early blight severity decreased from 22.1% at 45 DAS to 0.3 % at 60 DAS. The highest AUDPC value of late blight at Mouvou site was observed in NPK treatment while potato in CD treatment had the lowest. The lowest AUDPC value of early blight was observed in CD treatment at both sites. AUDSIPC value for late blight was significantly higher in NPK treatment in both sites. The highest value of AUDPSIC of early blight was recorded in MYC treatment, 45 DAS in both sites. The average rainfall was higher in the Gouria site (716.5mm) than in Mouvou site (679 mm). The CD treatment can be recommended to the farmers for the phytosanitary protection of potatoes.
Knowledge of the magnitude of genetic variability, heritability and genetic gains in selection of desirable characters could assist the plant breeder in ascertaining criteria to be used for the breeding programmes. Ten open pollinated maize varieties were evaluated at the Teaching and Research farm, University of Ilorin, Nigeria, during 2005 and 2006 cropping seasons to estimate genetic variability, heritability and genetic advance of grain yield and its component characters. The effect of genotype and genotype by year interaction were significant for ear weight and grain yield, while the effect of year was highly significant (P< 0.01) for all the characters. High magnitude of phenotypic and genotypic coefficient of variations as well as high heritability along with high genetic advance recorded for grain yield, number of grains ear-1, ear weight, plant and ear heights provides evidence that these parameters were under the control of additive gene effects and effective selection could be possible for improvement for these characters. Tze Comp3 C2, Acr 94 Tze Comp5, Tze Comp 4-Dmr Srbc2 and Acr 90 Pool 16-Dt were identified as outstanding genotypes for maize grain yield and should be tested at multilocation for their yield performance.
Evaluating the performance of improved sweet potato (Ipomoea batatas L. Lam) ...Innspub Net
Field trials were conducted in the 2014 rainy season at the Teaching and Research Farm of Bayero University, Kano (11°58’N and 8°25’E) and Agricultural Research Station Farm, Minjibir (12°11’N and 8°32’E). The objective of the study wasto evaluate the performance of improved sweetpotato lines with a view to identify those that may be adaptable with high yielding potential in the study area.The treatments consisted of 16 sweetpotato advanced lines: Centennial, AYT/08/055, TIS8164, TIS87/0087, NRSP12/097, UMUSPO/2, UMOSPO/1, SOLOMON-1, EA/11/022, EA/11/025, EA/11/003, UM/11/015, NRSP/12/095, UM/11/001, UM/11/022, and a local check
(Kantayiidda). These were laid out in a Randomized complete block design with 3 replications. Significant differences were observed in number of roots per plant, number of marketable roots, number of pencil roots, flesh colour, root shape and root yield. Kantayiidda produced significantly (p<0.05) higher root yield (10315kg/Ha) than all other lines. Solomon-1, Umuspo/1, EA/11/022, UM/11/001 and TIS87/0087 were found to be promising among the advanced lines evaluated; thus could relatively compete with Kantayiidda local for adaptation and high root yield in the study area. Get full articles at: http://www.innspub.net/volume-7-number-4-october-2015-ijaar/
Genetic resistance to drought and aflatoxin contamination in groundnuts in ce...Abadi Getahun
This poster presentation highlights the results gained from the experiment conducted at Rama, central zone of Tigray with the aim to screen different groundnut genotypes for their resistance to drought and natural aflatoxin contamination.
Geospatial Science and Technology Utilization in Agricultureijtsrd
Since the agrarian revolution during the 18th century, the use of technology to improve the effectiveness and efficiency of farming practices has increased tremendously. Discoveries in the field of science and technology have enabled farmers to effectively use their input to maximize their yield. These advancements have been greatly assisted by the use of sophisticated machineries, planting practices, use of fertilizers, herbicides and pesticides and so on. At the present moment however, the success of large scale farming highly relies on geographic information technology through what is known as precision farming. Precision agriculture, or precision farming, is therefore a farming concept that utilizes geographical information to determine field variability to ensure optimal use of inputs and maximize the output from a farm Esri, 2008 . Precision agriculture gained popularity after the realization that diverse fields of land hold different properties. Large tracts of land usually have spatial variations of soils types, moisture content, nutrient availability and so on. Therefore, with the use of remote sensing, geographical information systems GIS and global positioning systems GPS , farmers can more precisely determine what inputs to put exactly where and with what quantities. This information helps farmers to effectively use expensive resources such as fertilizers, pesticides and herbicides, and more efficiently use water resources. In the end, farmers who use this method not only maximize on their yields but also reduce their operating expenses, thus increasing their profits. On these grounds therefore, this article shall focus on the use of geospatial technologies in precision farming. To achieve this, the paper shall focus on how geospatial data is collected, analyzed and used in the decision making process to maximize on yields. Dr. Anil Kumar "Geospatial Science and Technology Utilization in Agriculture" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-4 , June 2022, URL: https://www.ijtsrd.com/papers/ijtsrd50330.pdf Paper URL: https://www.ijtsrd.com/biological-science/botany/50330/geospatial-science-and-technology-utilization-in-agriculture/dr-anil-kumar
Case Study to Investigate the Adoption of Precision Agriculture in Nigeria Us...Premier Publishers
This study investigated the adoption of precision farming (PF) technology with research into the possible implementation of the technology for increased productivity in a maize plantation in Nigeria. The research understands the nature of the challenges and highlights the possibility of implementing PF technology to Nigerian Agriculture. The methodology uses simple image analysis with fuzzy classification to determine the degree of spatial and temporal variability of the field to develop a treatment plan for an equally fertile and fully productive yield. The results showed that implementing precision agriculture (PA) will yield high productivity with the aid of remote sensing to obtain an aerial view of the farm. Simple PA technologies, such as using the information to determine and test soil nutrient availability to enable land preparation to obtain a uniform field, can help make the managerial decision on the farm efficiently. There is a great chance to optimize production on the field, minimise input resources, cost and maximising profit while preserving the natural environment. By using machine vision technology with fuzzy logic for decision making, not only the shape, size, colour, and texture of objects can be recognised but also numerical attributes of the objects or scene being imaged.
Spatial-temporal variation of biomass production by shrubs in the succulent k...Innspub Net
Forage production in arid and semi-arid rangelands is not uniform but varies with seasons and in various landscapes. The aim of this study was to investigate the spatial and temporal variation in forage production in RNP. Plants sampling was carried out in 225 plots distributed in each of the five vegetation types. In each vegetation strata, sampling points was based on proximity to an occupied stock post, a rain gauge, a foothill and flat plains. A total of were measured in the 5 study sites. Line Intercept Method in combination with harvest method were used in ground measurement of biomass production. To assess biomass production using remote sensing technique, par values were obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) imageries which consisted of 8 days composite images at spatial resolution of 1km² pixel size. There was positive correlation between line intercepts and biomass production Biomass production was higher in succulent Karoo biome than in desert biome. There was a strong relationship between biomass production with rainfall and with fpar values. Since leaf and stem succulents’ plants were found to contribute the highest amount of forage production in RNP, they should be given conservation priority.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
1. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
163
Remote sensing potential for investigation of maize production: review of literature
A. Ngie1*; F. Ahmed2; K. Abutaleb1
1 Department of Geography, Environmental Management and Energy Studies, University of Johannesburg, P.O. Box 524 Auckland Park 2006, South Africa
2 School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa
* Corresponding author: email: adelinengie@gmail.com, Tel.: +27 (0)11 559 2270
DOI: http://dx.doi.org/10.4314/sajg.v3i2.4
Abstract
Maize is considered globally as the most important agricultural grain which is staple food for many humans and feed to livestock. There is need to enhance productivity through management tools to meet the demand for growing populations. Farmers are likely to be interested in technologies that are beneficial to their operations. A technology that could assist farmers to produce staple foods e.g. maize more efficiently is remote sensing. The paper focuses on reviewing published research that deals with application of remote sensing in maize farming particularly the spectral characteristics of maize leaves, classification and mapping. It further surveys the application of remote sensing in detecting foliar nitrogen deficiency, water stress and disease infestations in maize. Remote sensing can be considered as a fast, non-destructive and relatively cost-effective method to study biophysical and biochemical parameters of vegetation across vast spatial areas. However, selection of appropriate sensors with special attention on their spatial and spectral resolutions as well as processing techniques will validate a success story for remote sensing application in maize production.
Keywords: Maize · Nutrient monitoring · Remote sensing · Spectral reflectance · Yield predictions
2. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
164
1. Background
Maize has been considered globally as the most important agricultural grain which is staple food in many countries and feed to livestock. It is estimated that by 2050, the demand for maize in developing countries will double, and by 2025 maize will have become the crop with the greatest production globally (FARA, 2009). In 2006 the Abuja Summit on Food Security in Africa identified maize, among other crops, as a strategic commodity for achieving food security and poverty reduction. There was a call to promote maize production on the continent to achieve self-sufficiency by 2015 (AUC, 2006).
Maize production at macro level is limited by climate and soil. The potential areas maize can, therefore, be cultivated are geographically specific to these environmental conditions. At micro level, the determinant or stress factors to maize production would include among other factors water and nutrients deficiencies (nitrogen, phosphorus, potassium, etc.), insect pests, and diseases (Zhao et al., 2003). The proper functioning, growth and eventually yield output of the crop is influenced by these factors. Detection of stress levels to which maize production is subjected is therefore essential for assessing the effects on yield, taking action to mitigate these effects and enhancing production.
Precision agriculture is based on intensive sources of information and attempts to address the site-specific needs with spatially variable application. This involves close monitoring and controlling many aspects of crop production that should aid in identifying proper targets and needs of crops for applying locally varying doses of chemicals. For instance, Mondal et al. (2011) conducted a research to monitor plant nutrient and moisture needs, soil conditions, and plant health (including identification of disease infestation).
Effective crop planning and management requires informed and sound decisions drawn from knowledge about the crops in the field. In order to improve agricultural management, scientist are applying information technology (IT) and satellite-based technology (e.g. global positioning system, remote sensing etc.) to identify, analyze, monitor and manage the spatio-temporal variability of agronomic parameters (e.g.
3. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
165
nutrients, diseases, water, etc.) within crop fields. This aids in timely applications of only the required amount of inputs to optimize profitability, sustainability with a minimal impact on the environment (Mondal et al., 2011). There is therefore the assurance of proper resource utilization and management to enhance crop productivity.
The purpose of this paper was to review published research in maize production using remote sensing as major research tool. The review seeks to investigate the potential of using remotely sensed data and analytical techniques to enhance productivity of maize. This is achieved through an understanding of the spectral characteristics of maize leaves for varietal separation, classification and mapping. The ability of these spectral characteristics can be used to monitor the nutrient status and health condition of the maize leaves. The paper concludes with a summary and some recommendations for the application of remote sensing in the production of maize.
2. Spectral characteristics of maize leaves, classification and mapping
When energy strikes on a surface material, it is either absorbed or reflected back through the electromagnetic spectrum. The visible (400-700nm wavelength) and near infrared (NIR) (700-2500nm wavelength) region of the electromagnetic spectrum is the region at which most agricultural studies carry out measurements. This is because the spectral region includes wavelengths which are sensitive to physiological and biological functions of crops (Lillesand et al., 2008). The spectral characteristics of healthy vegetation are distinctive with low reflectance in blue, high in green, very low in red and very high in the NIR (Chen et al., 2010; Genc et al., 2013).
There is a large difference in the spectral characteristics between soil and crop, especially at the ‘red edge’ which is the point where the electromagnetic spectrum changes from visible to NIR (wavelength of approximately 700nm) (Figure 1). This region is used to detect biochemical and biophysical parameters in crops thereby being useful in vegetation studies. The principle is that the majority of the red light is absorbed by the chlorophyll in the canopy while a high proportion of the NIR light is reflected
4. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
166
(Ramoelo et al., 2012). The canopy greenness increases, either due to increasing crop density or chlorophyll content. Canopy greenness is therefore related to the percentage of red reflectance absorbed and the percentage NIR reflectance reflected (Lillesand et al., 2008). Therefore, the reflectance spectral techniques are very suitable for providing relevant information on both crop foliar and canopy which could be related to nutrient status and stress factors on the crops (Scotford & Miller, 2005; Ramoelo et al., 2012).
Measurements at the red-edge bands has made possible the estimation of foliar nutrients and chlorophyll concentrations in differing vegetation types at varying growth stages (Huang et al., 2004; Cho and Skidmore, 2006; Darvishzadeh et al., 2008; Mokhele & Ahmed, 2010). Therefore, remote sensing (both multispectral and hyperspectral) can therefore provide an effective means for fast and non-destructive estimation of leaf nitrogen and water status in crop plants through complimentary tools such as regression models (Yao et al., 2010).
Figure 1: Spectral reflectance curves for soil and crop (green vegetation) according to Scotford & Miller, 2005.
5. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
167
Spectral unmixing techniques can be used to quantify crop canopy cover within each pixel of an image and have the potential for mapping the variation in crop yield. Each image pixel contains a spectrum of reflectance values for all the wavebands measured. These spectra can be regarded as the signatures of surface components such as plants or soil, provided that components, referred to as endmembers, covers the whole pixel. Spectra from mixed pixels can be analyzed with linear spectral unmixing, which models each spectrum in a pixel as a linear combination of a finite number of spectrally pure spectra of the endmembers in the image, weighted by their fractional abundances (Yang et al., 2007; 2010). Spectral unmixing is an alternative to soft classification for sub-pixel analysis (Lu and Weng, 2004). This is usually very essential in crop identification and classification studies. The classification is performed under either supervised techniques which include maximum likelihood, minimum distance, parallelepiped etc or unsupervised technique.
Adding to traditional unsupervised and supervised classification methods are advanced techniques such as artificial neural networks (ANN), support vector machines (SVM), decision trees (DT) and image segmentation which have been used to classify remote sensing data (Lu & Weng, 2007; Mathur & Foody, 2008). However, these classifiers remain to be evaluated using different types of remote sensing data from diverse crop growing environments. There is also the field-based crop identification which entails field boundary information and results in higher classification accuracy (De Wit & Clevers, 2004).
Remote sensing has played a significant role in crop classification for various purposes. Effective crop classification requires an understanding of the spectral characteristic (foliar and canopy levels) of the particular crop. In order to understand for instance the maize canopy spectral characteristics, a field investigation is targeted when the plant canopy is covered which is usually during six to eight weeks after planting. The light reflectances acquired during such growth stages could apply in differentiation of varieties; classification and mapping of maize varieties. For instance, Yang et al. (2011) used maximum likelihood and SVM classification techniques on SPOT 5 imagery to identify crop types and to estimate crop areas. Different band ratios of multispectral or
6. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
168
hyperspectral data and classifications schemes have been applied, depending on geographic area, crop diversity, field size, crop phenology and soil condition (Nellis et al., 2009).
To extract vegetation species from hyperspectral imagery, a set of signature libraries of vegetation are usually required (Xavier et al., 2006). For certain applications, the vegetation libraries for particular vegetation species might be already available. However, for most cases, the spectral signature library is established from data collected with a spectrometer. As such, vegetation mapping using hyperspectral imagery must be well designed to collect synchronous field data for creating imagery signatures (Melgani, 2004).
In most agricultural studies, spectral reflectance values of at least two wavelength bands (on either sides of the ‘red edge’) are measured to enable the calculation of a ratio. These ratios are known as vegetation indices and many have been developed over the years. These indices are usually correlated against field observations of nutrient stress measured at foliar or canopy level. The number of wavelength bands measured will determine the complexity of the data analysis; wherein a small number of bands will translate to a simple data analysis. This could be illustrated in a scenario where in situ measured reflectance values of the red and NIR wavelengths are used to calculate normalized difference vegetation index (NDVI).
However this only holds true until canopy closure when the crop has a leaf area index (LAI) of up to three where LAI is defined as the ratio between total leaf area, one side only, per unit area of ground (Scotford & Miller, 2005). Mirik et al. (2012) also described spectral vegetation indices as mathematical expressions that involve reflectance values from different parts of the electromagnetic spectrum. These expressions are aimed at optimizing information and normalizing measurements made across different environmental conditions.
Shanahan et al. (2003) proposed a study evaluating the use of two indices (NDVI and green NDVI (GNDVI)) on a large plot scale. The experiment was conducted on four varieties of irrigated corn treated with five differing levels of nitrogen. Remote
7. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
169
measurements were taken with active sensors emitting light in four bands: blue (460nm), green (555nm), red (680nm), and NIR (800nm). The authors concluded that differences in NDVI was significantly impacted by nitrogen and sampling date. Also, increased nitrogen was correlated to increased chlorophyll content but not on a large scale. However, Strachan et al. (2002) recommended that canopy reflectance at red edge position can explain 81% of maize leaf nitrogen variability.
3. Monitoring nutrient stress in maize
3.1. Nitrogen deficiencies in maize
Nitrogen (N) is a biochemical nutrient essential for plant growth. It forms part of many structural, metabolic and genetic compounds. Nitrogen is a critical building block of Chlorophyll which is essential for the process of photosynthesis. Availability of N in the soil usually related to plant growth, photosynthetic capacity and stress (Ustin et al., 1998; Yao et al., 2010). Nitrogen deficiency in a plant will have symptoms on the lower, older leaves first before progressing upward to younger leaves if the condition is not corrected (Sawyer, 2004).
Nitrogen deficiencies interfere with protein synthesis and growth in crops such as maize (Bruns and Abel 2005). Numerous studies have been conducted to proof the direct effect of N to yield levels of maize (Lindquist et al., (2007); Shapiro and Wortmann, 2006; Singh et al., 2003; Abouziena et al., 2007; Savabi et al., 2013). Nitrogen deficiency-induced effects on kernel number could be related to photosynthesis or plant growth at flowering (Andrade et al., 2002). Gitelson et al. (2005) developed a model, based upon field measurements made by means of a hyperspectral radiometer, for non- destructive estimation of chlorophyll in maize and soybean canopies.
Nitrogen deficiency could be detected earlier in crops when visual symptoms of deficiency are less evident with the use of remote sensors (Jackson et al., 1981). This is achieved through its various compounds providing an effective means for monitoring growth status and physiological parameters in crop plants. Its presence in chlorophyll and other cellular structures influences information on spectral reflectance (Yao et al., 2010).
8. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
170
The measurement of chlorophyll content is also important with regard to N management. Hence, a number of studies have utilised remote sensing techniques to determine the status of nitrogen and other essential nutrients in field crops such a maize and wheat as illustrated through this review.
Zhao et al. (2003) induced differing levels of nitrogen stress on corn and measured growth parameters, chlorophyll concentration, photosynthetic rates, and reflectance. The study demonstrated that reductions in leaf nitrogen concentrations are greater in plants suffering from inadequate soil N availability. Reduced nitrogen concentrations were correlated with lower rates of stem elongation and leaf area. The authors in 42 days after crop emergence noticed a 60% reduction in chlorophyll a, which caused an increased reflectance near 550 and 710nm. Therefore, reduced chlorophyll concentrations as a result of stress translate in decreased light absorbency and increased reflectance in these wavelength regions.
Remotely sensed imagery can provide valuable information about in-field N variability in maize as well as variability at canopy level still using the relationship with N content. Maize leaf reflectance (near 550nm wavelength) has a good relationship with leaf N content (Osborne et al., 2002). Martin et al. (2007) found that NDVI increased with maize growth stage during the crop life cycle and a linear relationship with grain yield is best at the V7–V9 maize growth stages.
Solari et al. (2008) investigated the potential use of active sensors at a field scale in determining N status in corn. Irrigated plots with uniform soils and fertilization, excluding N, were established at the initial stage and later differing rates and timing of nitrogen applications were administered in order to induce variable growth patterns. The authors discovered that the NDVI was sensitive to differences in N, hybrid, and growth stage. There exist a strong linear relationship between leaf chlorophyll concentration and leaf N concentration, where the greater leaf area and green plant biomass levels result in higher reflectance and higher subsequent NDVI values (Inman et al., 2007). This implies that these variables (leaf area and plant biomass) are directly related to the N content of
9. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
171
the plant; hence higher NDVI values indicate higher plant N content (Shaver et al., 2011).
3.2. Water stress in maize
The saying that ‘water is life’ denotes for both flora and fauna. Water is a key determinant in the production of crops with maize inclusive. Accurate water content estimation is required to make decisions on irrigation and also crop yield estimations in agricultural studies (Peñuelas et al., 1993). The water content/status of a plant can be measured from root, stem and leaf material or the whole canopy. Leaf analyses are however, the most important organ for evaluating nutrient and water status of plants in comparison to other tissue types (Suo et al., 2010). The leaf is also mostly responsible for photosynthesis, an essential physiological process in plants. Hence, the health and nutrient status with water status inclusive of the plants can be evaluated from the leaves.
Considerable technological developments have taken place over the years to determine water stress using remote sensing. The basis of detecting water stress relates to the differences in reflectance properties of plants under different water stress levels at certain wavelengths in the NIR portion of the electromagnetic spectrum (Genc et al., 2013). Two spectral regions have been found useful for detecting water status in plants; one characterised by high reflectance caused by reflections and scattering of light in the spongy mesophyll layer (NIR 0.7 – 1.3μm) and the other characterised by strong water absorption (mid infrared (MIR) 1.3 – 3.0μm). The first one is based on the turgor pressure in the leaf tissues while the second is directly related to leaf water content. The reflectance spectra of water stressed plants absorb less light in the visible and more light in the NIR regions of the spectrum than plants not experiencing water stress.
As a result of the absorption by oxygen-hydrogen (O–H) bonds in water, its absorption features could be found at approximately 760nm, 970nm, 1200nm, 1450nm, and 1950nm (Li, 2006). The first derivatives of reflectance associated with the slopes of the lines near water-absorption wavelength bands 900nm and 970nm correlates well with leaf water content (Danson et al., 1992). Studies have shown that reflectance spectra of green vegetation in the 900-2500nm region are associated with liquid water absorption and are
10. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
172
also weakly affected by other biochemical components absorption. It is possible to investigate the effect of water on nutrient stress (nitrogen) through discrimination based on the visible and NIR reflectance of maize leaves (Christensen et al., 2005). Prior knowledge of water status of plants can increase the ability to discriminate nutrient stress significantly.
The water band index is derived from the ratio of reflectance measured at 900nm and 970nm (Peñuelas et al., 1993). This spectral index has been correlated with ground-based measurements of plant water content at both the leaf and canopy scales. It is, however, more sensitive to leaf water content than the water content of the whole plant. This is advantageous in agricultural applications where leaf water content changes more noticeably in response to drought conditions than the water content of the entire plant foliage (Champagne et al., 2003). Leaf water content can be measured with the spectrometer to determine available water to the plants.
Genc et al. (2013) conducted an experiment on corn plants where reflectance measurements were made at the red and NIR portions before and after irrigation application. The results confirmed a decrease and increase in reflectance spectral at respective regions as the water level at field capacity increases. However, when the authors compared results at all four water levels, the reflectance spectra indicated that water stressed corn plants absorbed less light in the visible and more light in the NIR regions of the spectrum than unstressed plants.
A recent significant breakthrough in passive optical remote sensing has been the development of hyperspectral sensors on satellite platforms (such as EO-1 Hyperion) that provide continuous narrow bands and high resolution in the visible and infrared spectral region. Compared with multispectral imagery that only has a dozen of spectral bands, hyperspectral imagery includes hundreds of spectral bands. Hyperspectral sensors are well suited for vegetation studies as reflectance/absorption spectral signatures from individual species as well as more complex mixed-pixel communities can be better differentiated from the much wider spectral bands of its imagery (Yang et al., 2010). However, the interpretation of this hyperspectral data can be complicated by the inter-
11. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
173
relationships between wavelength variables but many statistical techniques have been utilised to analyse such data. For example, neural networks; partial least-squares analysis; fuzzy logic; principle component analysis and stepwise multiple linear regression have all been used (Xie et al., 2008).
Maize growth rate can be used as a good predictor of kernel number when nitrogen and water supply are considered as variables. This relationship was proven by modifying maize growth rate by N and/or water supply to that similarly obtained when plant growth was changed by variations in plant density and incident radiation. The effect of reducing N availability was similar to the effect of reducing water availability (Andrade et al., 2002).
Thus, the effect of water deficiencies, nitrogen stress, plant density, and incident radiation on maize kernel set can be predicted through a relationship between growth rate and kernel number. This is explained by two aspects: the correlation between growth rate at flowering to growth of reproductive structures, and also that early seed development and kernel set in maize is dependent on a continued supply of assimilates from concurrent photosynthesis (Zinselmeier et al., 2000).
A few water indices have been developed to study crop stress which include the water band index (WBI) (Peñuelas et al., 1993), shortwave infrared water stress index (SIWSI) (Fensholt & Sandholt, 2003) and normalized difference water index (NDWI) (Gao, 1995; Serrano et al., 2000). Recent studies have focused on combining the blue, green, red with blue and the NIR wavelengths in indices to estimate vegetation water content (Table 1) (Genc et al., 2013). Therefore, the use of remote sensing is particularly and practically suitable for assessing water stress and implementing appropriate management strategies because it presents unique advantages of repeatability, accuracy and cost-effectiveness over ground-based survey methodologies for water stress detection.
12. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
174
Table 1: Spectral indices and some wavelength bands used to detect water stress in maize
Index
Abbreviation and formula
Reference
Normalized difference vegetation index
NDVI = (NIR − R) / (NIR + R)
Rouse et al., 1973
Green NDVI
GNDVI = (NIR − G) / (NIR + G)
Gitelson & Merzlyak, 1996
Simple ratio
SR = R / NIR
Jordan, 1969
Normalized difference water index
NDWI = (G – NIR)/(G + NIR)
Gao, 1995; Mcfeeters, 1996; Serrano et al., 2000
Water band index,
WBI = 970nm/ 900nm
Peñuelas et al., 1993
Shortwave infrared water stress index
SIWSI(6,2)= (r6 -r2)/( (r6+r2) (10) or SIWSI(5,2)= (r5 -r2)/( (r5+r2) (band 6 and 5 respectively of MODIS);
SIWSI = SWIR−R(Rd) and SWIR+ R(Rs).
Fensholt & Sandholt, 2003; Haixia et al., 2013
Ratio of blue and NIR
BN = B / NIR
Genc et al., 2013
Ratio of green and NIR
GN = G / NIR
Genc et al., 2013
Ratio of red + green and NIR
RGN = (R + G) / NIR
Genc et al., 2013
SWIR (short wave infrared); NIR (near infrared); R (red); G (green); B (Blue)
13. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
175
3.3. Disease detection
Detection and identification of plant diseases and planning effective control measures are important to sustain crop production. Maize production is challenged by disease attacks ranging from insect to fungi. Plant diseases do not only affect yields but also increase the cost of production through treatment procedures on the crops. Some of the common diseases on the maize crop include but are not limited to grey leaf spot, common rust, northern corn leaf blight, phaeosphaeria leaf spot, maize streak disease, stem rot diseases and others.
When crops are infested by a disease, the biochemical constituent of the plant changes and so would be the spectral signatures. This is the reason why remote sensing could be used to monitor the infestation of diseases in field crops. Applications of remote sensing in field crops, for rapid detection of pest damage or disease, also include the use of handheld optical devices (Sudbrink et al., 2003; Moshou et al., 2004; Xu et al., 2007; Mirik et al., 2007) and airborne sensors (Sudbrink et al., 2003).
The health of the leaf can also be monitored wherein changes in leaf chlorophyll content provide an indicator of maximum photosynthetic capacity, leaf development and/or stress (Si et al., 2012). Assessment of photosynthetic functioning is one of the most important bases for the diagnosis and prediction of plant growth and subsequent yield estimation.
Williams et al. (2012) used the potential of the hyperspectral NIR imaging to evaluate fungal contamination in maize kernels. Using the principal component analysis (PCA), bad pixels as well as shading of acquired absorbance images were removed before further analysis. They concluded that the methodologies used were able to detect infection, the degree of infection and increase of infection over time. Therefore, remote sensing could assist in early detection of disease infestation in maize.
14. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
176
4. Crop yield predictions
Crop yield prediction is production estimates that are made a couple of months before the actual harvest. This is frequently done through computer programmes that utilize agro-meteorological data soil data, remotely sensed and agricultural statistics to describe quantitatively the plant-environment interactions (Dixon et al., 1994; Zere et al., 2004). In some instances, meteorological data is included to run some of the yield models (Unganai & Kogan, 1998). The meteorological data is usually generated from weather stations and cover a given area.
Crop phenology is fundamental to crop management, where timing of management practices is increasingly based on stages of crop development. The development of maize is subdivided into ten growth stages which summarily fall between the vegetative and reproductive phases. Plant development (phenology) is influenced by a variety of factors such as available soil moisture, date of planting, air temperature, day length, soil condition and nutrients. These factors therefore also influence the plant’s condition and productivity (Nellis et al., 2009). In order to achieve maximum production, vegetative stage three (four to six weeks after emerging) is more vital. This because at growth stage three there are eight to twelve leaves of the new maize plant that are fully unfolded. This is the stage of applying sprays and fertilizers. The yield potential of the plants is determined at this stage depending on the moisture and nutritional conditions at the time (Andrade et al., 2002).
Maize yield is usually associated with the kernel number at harvest and is a function of the physiological condition of the maize crop during the reproductive phases - bracketing, flowering or silking (Otegui & Andrade, 2000). Andrade et al., 2002 also determined that Kernel number can be related to photosynthetic activity via chlorophyll content.
Remote sensing techniques can be used to extract information about biophysical and biochemical parameters of vegetation such as LAI, chlorophyll, phosphorus, fibre, lignin, N (Darvishzadeh et al., 2008; Ramoelo et al., 2011) and silicon (Mokhele & Ahmed, 2010) which are essential for the plant growth. Statistical regression techniques are used to derive specific vegetation parameters and indices (Darvishzadeh et al., 2008; Si et al.,
15. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
177
2012) that could be utilised in estimating crop productivity. For instance, the LAI is used to quantify canopy structure, crop growth and hence predict primary productivity.
High correlations are found between vegetation indices and green biomass in studies done at field level (Groten, 1993). This is related to the crop type and yields but requires ground truthing and actual yield measurements in selected fields (pixels) that cover the full range of observed vegetation indices such as NDVI values. Viña et al. (2004) using visible atmospherically resistant spectral indices documented a capability for detecting changes in corn due to biomass accumulation, changes induced by the appearance and development of reproductive structures, and the onset of senescence.
Shanahan et al. (2001) used remotely sensed imagery to compare different vegetation indices as a means of assessing canopy variation and its resultant impact on corn (Zea mays L.) grain yield. Results showed that green normalized difference vegetation index (GNDVI), developed by Gitelson et al. (1996), derived from images acquired during midgrain filling were the most highly correlated with grain yield (Table 1). Therefore GNDVI could be used to produce relative yield maps depicting spatial variability in fields, offering a potentially attractive alternative to use of a combine yield monitor.
While most studies on yield prediction with remotely sensed data apply multispectral data due to its availability, hyperspectral images could also be utilised. For instance, Uno et al. (2005) statistically analysed hyperspectral images with an artificial neural network (ANN) and vegetation indices to develop models to predict yields for maize in Canada. After using the PCA to reduce the number of input variables for analysis, a greater prediction accuracy (20% validation) was obtained with an ANN model than with either of the three conventional empirical models based on NDVI, SR or photochemical reflectance index (PRI).
The use of remote sensing to estimate biological crop yields is being explored in many countries such as the United States, China and India, and likely will become the keystone of agricultural statistics in the future (Zhao et al., 2007). The fact that crop productivity vary greatly across climatic regions since it depends on agroclimatic conditions, the application of remote sensing in this field would be necessary. The variability of these
16. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
178
conditions warrants models to be developed based on the conditions of different areas where the crops are planted. Moreover, there is room to improve on methodologies and principles already developed in the creation of new models.
5. Summary and recommendations
According to this review there is great potential for remote sensing to be used in investigating maize growth process in order to enhance production of this global crop. This is backed by the availability of products with higher spatial, spectral and temporal resolution becoming more efficient, affordable and cost-effective. Its success in biophysical vegetation parameters identification and monitoring through the various growth stages of maize has been studied even though not uniformly across the globe.
Spectral reflectance measurements can provide a basis for variable biophysical vegetation parameters. There is a good relationship between these parameters when the spectral reflectance is measured at the leaf scale. Research in the past has been undertaken to estimate foliar nitrogen concentrations in experimental fields using portable spectrometers, with promising results. However when measured at the canopy level the relationship is further complicated for various parameters (LAI, wet and dry biomass etc.) and therefore further research are needed.
Sensor readings were also found to be more associated with chlorophyll content during vegetative growth phases than during reproductive phases (Solari et al., 2008). Taking advantage of improvements in sensor characteristics and processing techniques, the use of remotely sensed data for yield predictions for maize is gaining grounds. This is contributing substantially in a more accurate description of within-field crop yield variability which is a great concern in precision agriculture. However, it is still a challenge to develop accurate operational maize yield-estimating models.
The challenge of water deficiency monitoring over a large spatial area has been overcome through the use of remote sensing. It is practically suitable for assessing water stress and implementing appropriate management strategies because it presents unique
17. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
179
advantages of repeatability, accuracy, and cost-effectiveness over the ground-based surveys for water stress detection.
One of the potential applications of remote sensing technique in agriculture is the detection of plant disease on extensive areas before the symptoms clearly appear on the plant leaves. This is advantageous because remote sensing detects biophysical changes before physiological changes are visible. The challenge of disease infestation on maize production warrants more investigation as not much was found during this literature survey. Early detection and delineation of maize infested areas especially in some of the high productive areas that are prone to diseases (e.g. grey leaf spot) using hyperspectral remotely sensed data could be attempted. Therefore, spectroscopy analysis could be considered as an efficient technique for non-destructive, rapid, and accurate measurement which is widely applied in agricultural fields for crop discrimination, monitoring of nutritional status as well as diseases (Sankaran et al., 2010).
Acknowledgement
The funding for this research was provided through the University of Johannesburg bursary schemes. The authors also appreciate the inputs from the anonymous reviewers to this paper.
References
Abouziena, H. F., M. F. El-Karmany, M. Singh and S. D. Sharma, 2007: Effect of Nitrogen Rates and Weed Control Treatments on Maize Yield and Associated Weeds in Sandy Soils. Weed Technology 21(4), 1049-1053.
Andrade, F.H., L. Echarte, R. Rizzalli, A.D. Maggiora and M. Casanovas, 2002: Kernel Number Prediction in Maize under Nitrogen or Water Stress. Crop Science 42, 1173-1179.
AUC (African Union Commission), 2006: Resolution of the Abuja Food Security Summit. Addis Ababa, Ethiopia. http://www.fara- africa.org/media/uploads/library/docs/policy_briefs/patterns_of_change_in_maize_production_in_africa.pdf Accessed 2/09/2013
Bruns, H.A. and C.A. Abel, 2005: Nitrogen fertility effects on bt -endotoxin and nitrogen concentrations of maize during early growth. Agronomy Journal 95, 207-211.
Champagne, C.M., K. Staenz, A. Bannari, H. Mcnairin and J.C. Deguise, 2003: Validation of a hyperspectral curve fitting model for the estimation of plant water content of agricultural canopies. Remote Sensing of Environment 87, 148-160.
18. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
180
Chen, P., D. Haboudane, N. Tremblay, J. Wang, P. Vigneault and B. Li, 2010: New spectral indicator assessing the efficiency of crop nitrogen treatment in corn and wheat. Remote Sensing of Environment 114, 1987-1997.
Cho, M.A. and A.K.. Skidmore, 2006: A new technique for extracting the red edge position from hyperspectral data: the linear extrapolation method. Remote Sensing of Environment 101(2), 181-193.
Christensen, L. K., S.K. Upadhyaya, B. Jahn, D.C. Slaughter, E. Tan and D. Hills, 2005: Determining the Influence of Water Deficiency on NPK Stress Discrimination in Maize using Spectral and Spatial Information. Precision Agriculture 6(6), 539-550.
Danson, F., M. Steven, T. Malthus and J. Clark, 1992: High-spectral resolution data for determining leaf water content. International Journal of Remote Sensing 13, 461-470.
Darvishzadeh, R., A. Skidmore, M. Schlerf, C. Atzberger, F. Corsi and M. Cho, 2008: LAI and chlorophyll estimation for a heterogeneous grassland using hyperspectral measurements. ISPRS Journal of Photogrammetry and Remote Sensing, 63, 409-426.
De Wit, A.J.W. and J.G.P.W. Clevers, 2004: Efficiency and accuracy of per-field classification for operational crop mapping. International Journal of Remote Sensing 25(20), 4091- 4112.
Dixon, B.L., S.E. Hollinger, P. Garcia and V. Tirupattur, 1994: Estimating Corn Yield Response Models to Predict Impacts of Climate Change. Journal of Agricultural and Resource Economics 19(1), 58-68.
Forum for Agricultural Research in Africa (FARA), 2009: Networking Support Function 3: Regional Policies & Markets. Patterns of Change in Maize Production in Africa: Implications for Maize Policy Development. Ministerial Policy Brief Series (Number 3). 8pages.
Fensholt, R. and I. Sandholt, 2003: Derivation of a shortwave infrared water stress index from MODIS near- and shortwave infrared data in a semiarid environment. Remote Sensing of Environment 87, 111-121.
Gao, B.C., 1995: NDWI – a normalized difference water index for remote sensing of vegetation liquid water from space. Remote Sensing of Environment 58, 257-266.
Genc, L., M. Inalpulat, U. Kizil, M. Mirik, S.E. Smith and M. Mendes, 2013: Determination of water stress with spectral reflectance on sweet corn (Zea mays L.) using classification tree (CT) analysis. Zemdirbyste-Agriculture 100(1), 81-90.
Gitelson, A. A. and N. Merzlyak, 1996: Signature analysis of leaf reflectance spectra: algorithm development for remote sensing of chlorophyll. Journal of Plant Physiology 148, 494- 500.
Gitelson, A., A. Vina, V. Ciganda, D. Rundquist and T. Arkebauer, 2005: Remote estimation of canopy chlorophyll content in crops. Geophysical Research Letters 32 pp. L08403 doi: 10.1029/2005GL022688.
Gitelson, A., Y. Kaufman, and M. Merzlyak, 1996: Use of a green channel in remote sensing of global vegetation from EOSMODIS. Remote Sensing and Environment 58, 289-298.
Groten, S.M.E., 1993: NDVI–crop monitoring and early yield assessment of Burkina Faso. International Journal of Remote Sensing 14(8), 1495-1515.
19. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
181
Haixia, F., C. Chen, H. Dong, J. Wang and Q. Meng, 2013: Modified Shortwave Infrared Perpendicular Water Stress Index: A farmland water stress monitoring method. Journal of Applied Meteorology and Climatology 52(9), 2024-2032.
Huang, Z., B.J. Turner, S.J. Dury, I.R.Wallis and W.J. Foley, 2004: Estimating foliage nitrogen concentration from HYMAP data using continuum removal analysis. Remote Sensing of Environment 93(1-2), 18-29.
Inman, D., R. Khosla, R.M. Reich and D.G. Westfall, 2007: Active remote sensing and grain yield in irrigated maize. Precision Agriculture 8, 241-252.
Jackson, R.D., C.A. Jones, G. Uehara and L.T. Santo, 1981: Remote detection of nutrient and water deficiencies in sugarcane under variable cloudiness. Remote Sensing of Environment 11, 327-337.
Jordan, C. F., 1969: Derivation of leaf area index from quality of light on the forest floor. Ecology 50, 663-666.
Li, M. Z., 2006: Spectroscopy Analysis Technology and Application. Beijing: Science Press.
Lillesand, T.M., R.W. Kiefer, and J.W. Chipman, 2008: Remote sensing and image interpretation. 6th edition. NJ: Wiley.
Lindquist, J.L., D.C. Barker, S.Z. Knezevic, A.R. Martin and D.T. Walters, 2007: Comparative nitrogen uptake and distribution in corn and velvetleaf (Abutilon theophrasti). Weed Science 55, 102-110.
Lu, D. and Q. Weng, 2004: Spectral mixture analysis of the urban landscape in Indianapolis with Landsat ETM+ imagery. Photogrammetric Engineering and Remote Sensing 70(9), 1053- 1062.
Lu, D. and Q. Weng, 2007: A survey of image classification methods and techniques for improving classification performance. International Journal of Remote Sensing 28 (5), 823-870. Martin, K. L. Martin, K. Girma, K. W. Freeman, R. K. Teal, B. Tubańa, D. B. Arnall, B. Chung, O. Walsh, J. B. Solie, M. L. Stone and W. R. Raun , 2007: Expression of variability in corn as influenced by growth stage using optical sensor measurements. Agronomy Journal 99, 384-389. Mathur, A. and G.M. Foody, 2008: Crop classification by support vector machine with intelligently selected training data for an operational application. International Journal of Remote Sensing 29(8), 2227-2240.
McFeeters, S.K., 1996: The use of the Normalized Difference Water Index (NDWI) in the delineation of open water features. International Journal of Remote Sensing 17(7), 1425- 1432.
Melgani, F., 2004: Classification of hyperspectral remote sensing images with Support Vector Machines. IEEE Transactions on Geoscience and Remote Sensing 42(8), 1778-1790.
Mirik M., R.J. Ansley, G.J. Michels Jr. and N.C. Elliott, 2012: Spectral vegetation indices selected for quantifying Russian wheat aphid (Diuraphis noxia) feeding damage in wheat (Triticum aestivum L.). Precision Agriculture 13, 501-516.
Mokhele, T.A. and F.B. Ahmed, 2010: Estimation of leaf nitrogen and silicon using hyperspectral remote sensing. Journal of Applied Remote Sensing 4(043560), 1-18.
20. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
182
Mondal, P., M. Basu and P.B.S. Bhadoria, 2011: Critical review of precision agriculture technologies and its scope of adoption in India. American Journal of Experimental Agriculture 1(3), 49-68.
Moshou, D., C. Bravo, J. West, S. Wahlen, A. McCartney and H. Ramon, 2004: Automatic detection of ‘yellow rust’ in wheat using reflectance measurements and neural networks. Computers and Electronics in Agriculture 44(3), 173-188.
Nellis, M., P. Price and D. Rundquist, 2009: Remote sensing of cropland agriculture. Papers in Natural Resources. Paper 217. The SAGE Handbook of Remote Sensing 26pp. http://www.sage-ereference.com/hdbk_remotesense/Article_n26.html . Chapter DOI: 10.4135/978-1-8570-2105-9.n26.
Osborne, S.L., J.S. Schepers, D. Francis and M.R. Schlemmer, 2002: Detection of phosphorus and nitrogen deficiencies in corn using spectral radiance measurements. Agronomy Journal 94(6), 1215-1221.
Otegui, M.E. and F.H. Andrade, 2000: New relationships between light interception, ear growth and kernel set in maize. p. 89-102. In M. Westgate and K. Boote (ed.) Physiology and modeling kernel set in maize. CSSA Spec. Publ. 29. CSSA, Madison, WI.
Pannar Seed, Know the Maize Plant. http://www.pannarseed.co.za/uploads/documents/40/Know%20The%20Maize%20Plant.pdf Accessed Nov 20 2012.
Peñuelas, J., I. Filella, C. Biel, L. Serrano and R. Save, 1993: The reflectance at the 950-970 region as an indicator of plant water status. International Journal of Remote Sensing 14 (10), 1887-1905.
Ramoelo, A., A.K. Skidmore, M.A. Cho, M. Schlerf, R. Mathieu and I.M.A. Heitkönig, 2012: Regional estimation of savanna grass nitrogen using the red-edge band of the spaceborne RapidEye sensor. International Journal of Applied Earth Observation and Geoinformation 19, 151-162.
Ramoelo, A., M.A. Cho, R. Mathieu, A.K. Skidmore, M. Schlerf, I.M.A. Heitkönig and H.H.T. Prins, 2011: Integrating environmental and in situ hyperspectral remote sensing variables for grass nitrogen estimation in savanna ecosystems, 34th International Symposium on the Remote Sensing of Environment (ISRSE). The GEOSS Era: Towards Operational Environmental Monitoring, Sydney, Australia, http://www.isprs.org/proceedings/2011/ISRSE-34/index.html Accessed November26 2012.
Rouse, J.W., Haas R.H., Schell J.A. and D.W. Deering, 1973: Monitoring vegetation systems in the Great Plains with ERTS: 3rd ERTS symposium. NASA, SP-351 (1), 309-317.
Sankaran, S., A. Mishra, R. Ehsani and C. Davis, 2010: A review of advanced techniques for detecting plant diseases. Computers and Electronics in Agriculture 72(1), 1-13.
Savabi, M.R., B.T. Scully, T.C. Strickland, D.G. Sullivan, and R.K. Hubbard, 2013: Use of statistical and conceptual path models to predict corn yields across management-zones on the Southeast Coastal Plain. Journal of Agricultural Science 1(2), 32-51.
Sawyer, J., 2004: Integrated pest management, nutrient deficiencies and application injuries in field crops. Unpublished report IPM 42 revised July 2004, Department of Agronomy, Iowa State University.
21. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
183
Scotford, I.M. and P.C.H. Miller, 2005: Applications of Spectral Reflectance Techniques in Northern European Cereal Production: A Review. Biosystems Engineering 90(3), 235- 250.
Serrano L., I. Fillella and J. Peñuelas, 2000: Remote sensing of biomass and yield of winter wheat under different nitrogen supplies. Crop Science 40, 723-731.
Shanahan, J.F., J.S. Schepers, D.D. Francis, G.E. Varvel, W.W. Wilhelm, J.M. Tringe, M.R. Schlemmer and D.J. Major, 2001: Use of remote-sensing imagery to estimate corn grain yield. Agronomy Journal 93, 583-589.
Shanahan, J.F., K. Holland, J.S. Schepers, D.D. Francis, M.R. Schlemmer, and R. Caldwell. 2003. Use of crop reflectance sensors to assess corn leaf chlorophyll content. In VanToai, T., D.Major, M. McDonald, J. Schepers, L.Tarpley, (Eds.) Digital imaging and spectral techniques: Applications to precision agriculture and crop physiology. Proceedings of a symposium sponsored by Division C-2 of the Crop Science Society of America, the USDA-ARS, and the Rockefeller Foundation in Minneapolis, MN, November 2001. ASA Special Publication. 66. ASA, Madison, WI. 135-150.
Shapiro, C.A. and C.S. Wortmann, 2006: Corn response to nitrogen rate, row spacing, and plant density in Eastern Nebraska. Agronomy Journal 98, 529-535.
Shaver, T. M., R. Khosla and D. G. Westfall, 2011: Evaluation of two crop canopy sensors for nitrogen variability determination in irrigated maize. Precision Agriculture. DOI 10.1007/s11119-011-9229-2.
Si, Y., M. Schlerf, R. Zurita-Milla, A. Skidmore and T. Wang, 2012: Mapping spatio-temporal variation of grassland quantity and quality using MERIS data and the PROSAIL model. Remote Sensing of Environment 121, 415-425.
Singh, R., R. Sutaliya, R. Ghatak, and S.K. Sarangi, 2003: Effect of higher application of nitrogen and potassium over recommended level on growth, yield, and yield attributes of late sown winter maize (Zea mays L.). Crop Research 26(l), 71-74.
Solari, F., J. Shanahan, R.B. Ferguson, J.S. Schepers and A.A. Gitelson, 2008: Active sensor reflectance measurements of corn nitrogen status and yield potential. Agronomy Journal 100, 571-579.
Strachan, I.B., E. Pattey and J.B. Boisvert, 2002: Impact of nitrogen and environmental conditions on corn as detected by hyperspectral reflectance. Remote Sensing of Environment 80, 213-224.
Sudbrink, D.L., F.A. Harris, J.T. Robbins, P.J. English and L.L. Willers, 2003: Evaluation of remote sensing to identify variability of cotton plant growth and correlation with larval densities of beet armyworm and cabbage looper (Lepidoptera: Noctuidae). Florida Entomologist 86, 290-294.
Suo, X.M., Y.T. Jiang, M. Yang, S.K. Li, K.R. Wang and C.T. Wang, 2010: Artificial neural network to predict leaf population chlorophyll content from cotton plant images. Agricultural Sciences in China 9(1), 38-45.
Unganai, L.S. and F.N. Kogan, 1998: Drought Monitoring and Corn Yield Estimation in Southern Africa from AVHRR Data. Remote Sensing of Environment 63(3), 219-232.
22. South African Journal of Geomatics, Vol. 3, No. 2, August 2014
184
Uno, Y., S.O. Prasher, R. Lacroix, P.K. Goel, Y. Karimi, A. Viau and R.M. Patel, 2005: Artificial neural networks to predict corn yield from Compact Airborne Spectrographic Imager data. Computers and Electronics in Agriculture 47(2), 149-161.
Ustin, S.L., M.O. Smith, S. Jacquemoud, M.M. Verstraete, and Y. Govaerts, 1998: GeoBotany: Vegetation mapping for Earth sciences, in A.N. Rencz (eds) Manual of Remote Sensing, vol. 3, Remote Sensing for the Earth Sciences, 3rd ed., pp. 189-248, Wiley: Hoboken.
Viña, A., A. Gitelson, D. Rundquist, G. Keydan, B. Leavitt and J. Schepers, 2004: Monitoring maize (Zea mays L.) phenology with remote sensing. Agronomy Journal 96, 1139-1147.
Williams, P.J., P. Geladi, T.J. Britz and M. Manley, 2012: Investigation of fungal development in maize kernels using NIR hyperspectral imaging and multivariate data analysis. Journal of Cereal Science 55, 272-278.
Xavier, A.C., B.F.T. Rudorff, Y.E. Shimabukuro, L.M.S. Berka and M.A. Moreira, 2006: Multi- temporal analysis of MODIS data to classify sugarcane crop. International Journal of Remote Sensing 27(4), 755-68.
Xie, Y., Z. Sha and M. Yu, 2008: Remote sensing imagery in vegetation mapping: a review. Journal of Plant Ecology 1(1), 9-23.
Xu, H.R., Y.B. Ying, X.P. Fu and S.P. Zhu, 2007: Near-infrared spectroscopy in detecting leaf miner damage on Tomato leaf. Biosystem Engineering 96, 447-454.
Yang, C., J. H. Everitt and J. M. Bradford, 2007: Airborne hyperspectral imagery and linear spectral unmixing for mapping variation in crop yield. Precision Agriculture 8(6), 279- 296.
Yang, C., J. H. Everitt and Q. Du, 2010: Applying linear spectral unmixing to airborne hyperspectral imagery for mapping yield variability in grain sorghum and cotton fields. Journal of the Application of Remote Sensing 4(1), 041887, 1-11.
Yang, C., J.H. Everitt and D. Murden, 2011: Evaluating high resolution SPOT 5 satellite imagery for crop identification. Computers and Electronics in Agriculture 75(2), 347-354.
Yao, X., Y. Zhu, Y. Tian, W. Feng and W. Cao, 2010: Exploring hyperspectral bands and estimation indices for leaf nitrogen accumulation in wheat. International Journal of Applied Earth Observation and Geoinformation 12, 89-100.
Zere, T.B., C.W. van Huyssteen and M. Hensley, 2004: Development of a simple empirical model for predicting maize yields in a semi-arid area. South African Journal of Plant and Soil 22(1), 22-27.
Zhao, D., K.R. Reddy, V.G. Kakani, J.J. Read and G.A. Carter, 2003: Corn (Zea mays L.) growth, leaf pigment concentration, photosynthesis and leaf hyperspectral reflectance properties as affected by nitrogen supply. Plant and Soil 257, 205-217.
Zhao, J., K. Shi, and F. Wei. 2007: Research and Application of Remote Sensing Techniques in Chinese Agricultural Statistics. Paper presented at the Fourth International Conference on Agricultural Statistics, October 22-24, Beijing, China. www.stats.gov.cn/english/icas/papers/P020071017422431720472.pdf.
Zinselmeier, C., J.E. Habben, M.E. Westgate and J.S. Boyer, 2000: Carbohydrate metabolism in setting and aborting maize ovaries. p. 1-13. In M.Westgate and K. Boote (ed.) Physiology and modeling kernel set in maize. CSSA Spec. Publ. 29. CSSA, Madison, WI.