AGRICULTURAL STATISTICS OF ROOTS AND TUBERS

PERCY ZOROGASTÚA C.
ROBERTO QUIROZ
MICHAEL POTTS
STEFFEN SCHULZ
INTRODUCTION
Potato crop has a production of more than 314000 MT/Y and is the fourth crop of
importance in the world. Swee...
There are reasons to believe that the statistics of FAO in Africa do not have a
relation to the actual cultivated area. Th...
Key questions:
Actual
What is?
How much is there ?
Where do we have ?
What is the current status?

Potential
How much more...
Agricultural statistics can be determined under two criteria:
one through the use of a List frame in which a list of
produ...
50

Generic spectral signatures

30
20

Dry vegetation

10

Green vegetation
water

0

% Reflectance

40

Soil

B

G

500
...
IMAGE ANALYSIS

Source: National Technical University of Athens
Statistics of Sweetpotato in Kumi district, UGANDA

Kumi
Kumi climatic diagram
90

160

80

140

70

120

60

100

50

80

40

60

30

40

20

20

10

0

0
Jan

Feb

Mar May Apr

...
CROPS REFLECTANCES
1
0.9

Reflectance

0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
300

400

500

600

700

800

900

1000

1100

12...
Classified SPOT Image of the Kumi district, May 2006
Classified SPOT Image of the Kumi district, October 2006
Confusion Matrix of Land Cover & Land Use of Kumi (%)
Ground
Truth
Classificati
on

Category

1

2

3

4

5

6

7

1
2
3

...
Area covered by different land use and plant cover categories, May and October 2006

44620 ha of sweetpotato
Area planted in Kumi for Sweet potato
30,000

25,000

Ha.

20,000

15,000

10,000

5,000

0
1992

1993

1994

1995

1996

...
Potato in the
Jeldu
district, West
Shewa region –
Ethiopia
Jeldu

Addis Ababa
Source: Google Earth
Source: Gildemacher et al, 2009
Image SPOT 5 XS 10/11/2012

Source: Spot Image-Astrium
Land Cover & Land Use Dec. 2012 in Jeldu, West Shewa – Ethiopia

Category
Forest/Shrubs
Grassland/Weeds/Bare soil
Wheat
Ba...
Confusion Matrix of Land Cover & Land Use of Jeldu District
Ground truth/
Classification
Potato
Grassland/Weeds
/Bare soil...
Conclusions
The radiometric evaluation and processing of the SPOT scenes of
the district of Kumi in Uganda have made it po...
The results suggest that the traditional statistics of sweet
potato was underestimated by about 37 % of total area.

Jeldu...
Thank you very much for your attention
p.zorogastua@cgiar.org
Agricultural statistics of roots and tubers
Agricultural statistics of roots and tubers
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Agricultural statistics of roots and tubers

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Remote sensing –Beyond images
Mexico 14-15 December 2013

The workshop was organized by CIMMYT Global Conservation Agriculture Program (GCAP) and funded by the Bill & Melinda Gates Foundation (BMGF), the Mexican Secretariat of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA), the International Maize and Wheat Improvement Center (CIMMYT), CGIAR Research Program on Maize, the Cereal System Initiative for South Asia (CSISA) and the Sustainable Modernization of the Traditional Agriculture (MasAgro)

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  • Reflectance is the property of any object when is illuminated by radiation in determined wavelength. It corresponds to this expression (light reflected /light incident)*100As far as you are recognized legally by your signature in the civil registration office, each object have a characteristic spectral signature that help us to discriminate or identify them; in the slide, Cyan curve correspond to clear water, Magenta curve to water with sediments, green signature to a green vegetation, red curve to a dry vegetation and the orange one identify a soil feature.
  • Image analysis include several steps depending on the type of interpretation. Images can be interpreted by visual or “manual” methodsand through digital procedures. Each one have their advantages, however they have in common elements that have to be in accountTone/color: normal human eyes, in average, can distinguish easily until 16 grey tones and several colors.Shape, everything in nature has a geometrical characteristic shape. Texture is the placement, arrangement of repetition of grey tones and white areas and color. Pattern is the spatial arrangement of objects on the ground. Shadows is a silhouette caused by solar illumination from the side indirectly we can measure the height of an object.Site/Association: Objects are placed adjacent to some water (river) or lakes, mountains, roads, a highway, a bridge, etc.All of these elements normally are used in groups of two or three for indentifying a feature
  • Sweetpotato is an staple food, orange fleshed roots are acquiring more importance as a food, and a source of A vitamin.In recent years, CIP has introduced several clones of orange flesh sweet potato in Africa, as a strategy to solve the severe vitamin A deficiency affecting the human population. This introduction requires precise information on the current area of sweet potato cultivation to assess the potential dissemination of the new germplasm and their beneficiaries, both in the spatial and time scales. This knowledge is necessary for estimating the production, marketable volumes, per capitaconsumption, required inputs and to orient research.
  • Kumi has two peak mean growing seasons for sweetpotato cropping that are related with the rain season, one in March-April and other in Jul-Aug
  • High resolution imagery was used to determine the area covered by sweet potato in Kumi.Kumi district is located in the north eastern part of Uganda, it is just in the center of the SPOT image.The image is a multispectral one, with a resolution of 25 square meters per pixel (5m x 5m)
  • Initially Kumi district was stratified using the SPOT image into two zones one humid area and a dry area Sampling work has been done in the field with the help of an ASD spectral radiometer and a Magellan GPS to measure and locate samples in Kumi in two seasons. Samples were used to perform a supervised classificationusing the ENVI software.Sweetpotato has an spectral signature that can be differentiated from other crops and plant covers. It shows a lower response in visible region and a higher response in near infrared.
  • This was the results for the first season in May of 2006
  • This is the result for the second growing season in October of 2006
  • Sweetpotato was discriminated from other land uses in 93 % of cases and not in 7 %
  • A comparison of our results with the information of the Ugandan Bureau of Statistics (UBOS) showed an underestimation of about 40 % less area covered by sweetpotato.
  • Potato is the fourth staple food of importance in the world. Ethiopia has severe famine problems, cereals are the main crops and potato area is increasing along its territory. A problem to determine Land cover & land use in the eastern part of Ethiopia is the presence of clouds during the growing season. For this reason it has been chosen dehaulmed potato fields for quantify the area covered by this crop. The end of Meher growing season in Jeldu Ethiopia was selected with the goal to determine the area covered by Potato
  • Due the presence of clouds we acquired a multispectral high resolution Spot imagery with 6.25 square meters (2.5 m x 2.5m). Sample fields were visited in December of 2012 and they had dehaulmed potato fields. 100 field samples were taken. A unsupervised classification combined with a visual or manual strategy were used to rebuilt the potato fields considering their shapes, sizes, NDVI and level of digital brightness.
  • As far as dehaulmed potato fields had different characteristics, an unsupervised classification was used combining a visual pattern of recognition taking into account shapes and sizes of the fields, association with NDVI and digital bright values of them and a group of samples that contain the potato fields.Results are shown in the map and 10 664 ha of potatoes were counted.
  • Potato dehaulmed fields were discriminated in 93.5 % of cases with 6.3 % of confusion mainly with weeds and fallow lands
  • Agricultural statistics of roots and tubers

    1. 1. AGRICULTURAL STATISTICS OF ROOTS AND TUBERS PERCY ZOROGASTÚA C. ROBERTO QUIROZ MICHAEL POTTS STEFFEN SCHULZ
    2. 2. INTRODUCTION Potato crop has a production of more than 314000 MT/Y and is the fourth crop of importance in the world. Sweet potato production reaches more than 110000 MT/year and occupies the seventh place in the world. In recent years, CIP has introduced several clones of orange flesh sweet potato in Africa, as a strategy to solve the severe vitamin A deficiency affecting the human population. This introduction requires precise information on cropping area to assess the potential dissemination of the new germplasm and their beneficiaries, both in the spatial and time scales. This knowledge is necessary for estimating the production, marketable volumes, per capita consumption, required inputs and to orient research. Potato is acquiring more importance in Ethiopia due to frequent adverse factors that cause famine problems. Information about the area and zones where potato is grown and production volumes are necessary, in order to provide agricultural inputs for increasing productivity
    3. 3. There are reasons to believe that the statistics of FAO in Africa do not have a relation to the actual cultivated area. This reasonable doubt is based on the fact that crop statistics related to small producers, are obtained through field sampling and survey techniques that have some limitations. CIP’s Production Systems and the Environment Sub-Program is developing and validating methodologies based on a) Spectroradiometry and the use of highresolution remote sensing images that provides reliable, accurate, and dynamic information for estimating cropping areas and b) Detection of recently dehaulmed potato areas
    4. 4. Key questions: Actual What is? How much is there ? Where do we have ? What is the current status? Potential How much more it could produce? Where else it could be?
    5. 5. Agricultural statistics can be determined under two criteria: one through the use of a List frame in which a list of production units that can be registered each one through a census or only taken some samples of them, and through the Area frame in which area of land cover & land use is determined. We have used the Area frame criteria, with the estimation of the cropping area derived from remote sensing products and field data, classifying high resolution satellite data and counting pixels. We utilized high resolution Spot images for building the agricultural statistics for the districts of Kumi (sweetpotato) in Uganda and Jeldu (potato) in Ethiopia
    6. 6. 50 Generic spectral signatures 30 20 Dry vegetation 10 Green vegetation water 0 % Reflectance 40 Soil B G 500 R NEAR IR 1000 MID INFRARED 1500 Wavelength in nanometers 2000 2500
    7. 7. IMAGE ANALYSIS Source: National Technical University of Athens
    8. 8. Statistics of Sweetpotato in Kumi district, UGANDA Kumi
    9. 9. Kumi climatic diagram 90 160 80 140 70 120 60 100 50 80 40 60 30 40 20 20 10 0 0 Jan Feb Mar May Apr Jun Jul Aug Sep Oct Months Pp ET T max T min Nov Dic Temperature (ºC ) 100 180 Precipitation / ET (mm) 200
    10. 10. CROPS REFLECTANCES 1 0.9 Reflectance 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 300 400 500 600 700 800 900 1000 1100 1200 Wavelength Maize Bare Soil Millet Sweet potato Cassava Banana
    11. 11. Classified SPOT Image of the Kumi district, May 2006
    12. 12. Classified SPOT Image of the Kumi district, October 2006
    13. 13. Confusion Matrix of Land Cover & Land Use of Kumi (%) Ground Truth Classificati on Category 1 2 3 4 5 6 7 1 2 3 Forest/Mango Water bodies Clouds 92.9 0 0 0 100 0 0 0 100 0.6 0 0 0 0 0 0 0 0 0 0 0 4 Sweetpotato 5.9 0 0 93.1 0 0 0 5 6 7 Grassland Other crops Bare soil Total 0.6 0.6 0 100 0 0 0 100 0 0 0 100 0 6.4 0 100 100 0 0 100 17.4 82.5 0 100 0 0 100 100
    14. 14. Area covered by different land use and plant cover categories, May and October 2006 44620 ha of sweetpotato
    15. 15. Area planted in Kumi for Sweet potato 30,000 25,000 Ha. 20,000 15,000 10,000 5,000 0 1992 1993 1994 1995 1996 1997 Year Source: Uganda Bureau of Statistics 1998 1999 2000 2001 2002 2,003 The area projected to 2006 according to official statistical records, compa red with our results was 63 % of the total surface covered by sweetpotato
    16. 16. Potato in the Jeldu district, West Shewa region – Ethiopia Jeldu Addis Ababa Source: Google Earth
    17. 17. Source: Gildemacher et al, 2009
    18. 18. Image SPOT 5 XS 10/11/2012 Source: Spot Image-Astrium
    19. 19. Land Cover & Land Use Dec. 2012 in Jeldu, West Shewa – Ethiopia Category Forest/Shrubs Grassland/Weeds/Bare soil Wheat Barley Teff Potato Urban Area / Infraestructure Other crops ND Total Area (Ha) 34635.9 16880.5 26284.1 14886.4 6210.6 10663.6 4098.6 13503.0 4078.0 131240.7 % 26.4 12.9 20.0 11.3 4.7 8.1 3.1 10.3 3.1 100.0 Source: CIP, based on: XS SPOT image
    20. 20. Confusion Matrix of Land Cover & Land Use of Jeldu District Ground truth/ Classification Potato Grassland/Weeds /Bare soil/Fallow Forest Wheat Teff Barley Urban area/ Infrastructure Total Urban area/ Potato Grassland Forest Wheat Teff Barley Infrastr. 93.5 0 0 0 0 0 11.3 6.3 0.0 0.0 0.0 0.2 78.6 0 0 21.4 0 0 100 0 0 0 0 0 70.8 0 29.2 0 0 0 0 2 0 0 1 0 99 7.2 0 0 0 0 0.0 100.0 0 100 0 100 0 100 0 0 1 100 81.4 100
    21. 21. Conclusions The radiometric evaluation and processing of the SPOT scenes of the district of Kumi in Uganda have made it possible to determine that the sweet potato foliage has a distinct spectral pattern defined by a low reflectance in the visible range of the spectrum and a high reflectance in the near infrared range. This spectral pattern makes it possible to identify the sweet potato crop with a high degree of certainty, which allows defining with precision the cultivated area and the spatial distribution of the crop through the utilization of high-resolution SPOT images.
    22. 22. The results suggest that the traditional statistics of sweet potato was underestimated by about 37 % of total area. Jeldu district in Ethiopia has 131240.7 ha, where we determined 10386.4 ha with potato (7.9 %) as to December of 2012. Jeldu is dominated by cereals cropping which occupy 36% of the total area. Forest area and scrubland occupy the 26.4% of the total. Grasses, weeds and bare soils occupy 13% of total. Urban area and infrastructure cover the 3.1% and 13.4% of total area were covered by other crops
    23. 23. Thank you very much for your attention p.zorogastua@cgiar.org

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