This study uses a meta-analysis of 66 studies to compare yields from organic and conventional farming systems globally. The analysis finds that on average, organic yields are 25% lower than conventional yields. However, the yield differences are highly contextual and range from 5-34% depending on crop type, soil and climate conditions, and management practices. Organic systems tend to have lower yields for cereals and vegetables but similar yields as conventional for fruits and oilseeds. Better organic management practices and growing legumes or perennials can help narrow the yield gap between organic and conventional systems.
IRF ORganic Farming Technology : Biodiversity Marker can be effectively used to score the influence of any Management Practice towards development of agro-ecology, not only for tea plantation but for any type crop production.
Nutrient budgets are becoming accepted tools to describe nutrient flows within cropping system and to assist in the planning of the rotational cropping and mixed farming system
Depending on the farm management and the balance of inputs and outputs of nutrient N,P and K budgets have been shown to range from deficit to surplus in cropping system
Budgets are the outcome of simple nutrient accounting process which details all the inputs and outputs to a given defined system over fixed period of time
A soil surface nutrient budget accounts for all nutrients that enter the soil surface and leave the soil through crop uptake.
Island financial resource impacts from microbial ecosystem fermentation Johnny Rodrigues
Managed Ecosystem Fermentations (MEF) can bring business, financial and environmental benefits to island economies by generating multiple revenue streams from organic waste that currently requires expensive disposal. MEF systems do not require sterile feedstocks and are
capable of multiple concurrent products, offering a ten-fold increase in revenue compared to stand-alone biogas using the organic waste feedstock and reducing disposal volumes by 90%. MEF consumes many organic waste materials including feed grade (FG) fruit and vegetable waste, municipal solid wastes (MSW) and sewage sludge (SS). Different feedstocks make different products, increasing local economic diversity. Carbohydrates and cellulose in FG materials are converted to High Protein Animal Feed (HPAF), displacing soybean meal imports. MSW and SS can be used to produce enzymes, proteins and amino acids for use in other industrial processes providing export revenue. All of the MEF systems can produce
enough byproduct bio-methane to self-power their process with a potential surplus thereby reducing fuel imports.
Co hydrolysis of lignocellulosic biomass for microbial lipid accumulationzhenhua82
The herbaceous perennial energy crops miscanthus, giant reed, and switchgrass, along with the annual crop residue corn stover, were evaluated for their bioconversion potential. A co-hydrolysis process, which applied dilute acid pretreatment, directly followed by enzymatic saccharification without detoxification and liquidsolid separation between these two steps was implemented to convert lignocellulose into monomeric sugars (glucose and xylose). A factorial experiment in a randomized block design was employed to optimize the co-hydrolysis process. Under the optimal reaction conditions, corn stover exhibited the greatest total sugar yield (glucose+xylose) at 0.545gg1 dry biomass at 83.3% of the theoretical yield, followed by switch grass (0.44gg1 dry biomass, 65.8% of theoretical yield), giant reed (0.355gg1 dry biomass, 64.7% of theoretical yield), and miscanthus (0.349gg1 dry biomass, 58.1% of theoretical yield). The influence of combined severity factor on the susceptibility of pretreated substrates to enzymatic hydrolysis was clearly discernible, showing that co-hydrolysis is a technically feasible approach to release sugars from lignocellulosic biomass. The oleaginous fungus Mortierella isabellina was selected and applied to the co-hydrolysate mediums to accumulate fungal lipids due to its capability of utilizing both C5 and C6 sugars. Fungal cultivations grown on the co-hydrolysates exhibited comparable cell mass and lipid production to the synthetic medium with pure glucose and xylose. These results elucidated that combining fungal fermentation and co-hydrolysis to accumulate lipids could have the potential to enhance the utilization efficiency of lignocellulosic biomass for advanced biofuels production.
IRF ORganic Farming Technology : Biodiversity Marker can be effectively used to score the influence of any Management Practice towards development of agro-ecology, not only for tea plantation but for any type crop production.
Nutrient budgets are becoming accepted tools to describe nutrient flows within cropping system and to assist in the planning of the rotational cropping and mixed farming system
Depending on the farm management and the balance of inputs and outputs of nutrient N,P and K budgets have been shown to range from deficit to surplus in cropping system
Budgets are the outcome of simple nutrient accounting process which details all the inputs and outputs to a given defined system over fixed period of time
A soil surface nutrient budget accounts for all nutrients that enter the soil surface and leave the soil through crop uptake.
Island financial resource impacts from microbial ecosystem fermentation Johnny Rodrigues
Managed Ecosystem Fermentations (MEF) can bring business, financial and environmental benefits to island economies by generating multiple revenue streams from organic waste that currently requires expensive disposal. MEF systems do not require sterile feedstocks and are
capable of multiple concurrent products, offering a ten-fold increase in revenue compared to stand-alone biogas using the organic waste feedstock and reducing disposal volumes by 90%. MEF consumes many organic waste materials including feed grade (FG) fruit and vegetable waste, municipal solid wastes (MSW) and sewage sludge (SS). Different feedstocks make different products, increasing local economic diversity. Carbohydrates and cellulose in FG materials are converted to High Protein Animal Feed (HPAF), displacing soybean meal imports. MSW and SS can be used to produce enzymes, proteins and amino acids for use in other industrial processes providing export revenue. All of the MEF systems can produce
enough byproduct bio-methane to self-power their process with a potential surplus thereby reducing fuel imports.
Co hydrolysis of lignocellulosic biomass for microbial lipid accumulationzhenhua82
The herbaceous perennial energy crops miscanthus, giant reed, and switchgrass, along with the annual crop residue corn stover, were evaluated for their bioconversion potential. A co-hydrolysis process, which applied dilute acid pretreatment, directly followed by enzymatic saccharification without detoxification and liquidsolid separation between these two steps was implemented to convert lignocellulose into monomeric sugars (glucose and xylose). A factorial experiment in a randomized block design was employed to optimize the co-hydrolysis process. Under the optimal reaction conditions, corn stover exhibited the greatest total sugar yield (glucose+xylose) at 0.545gg1 dry biomass at 83.3% of the theoretical yield, followed by switch grass (0.44gg1 dry biomass, 65.8% of theoretical yield), giant reed (0.355gg1 dry biomass, 64.7% of theoretical yield), and miscanthus (0.349gg1 dry biomass, 58.1% of theoretical yield). The influence of combined severity factor on the susceptibility of pretreated substrates to enzymatic hydrolysis was clearly discernible, showing that co-hydrolysis is a technically feasible approach to release sugars from lignocellulosic biomass. The oleaginous fungus Mortierella isabellina was selected and applied to the co-hydrolysate mediums to accumulate fungal lipids due to its capability of utilizing both C5 and C6 sugars. Fungal cultivations grown on the co-hydrolysates exhibited comparable cell mass and lipid production to the synthetic medium with pure glucose and xylose. These results elucidated that combining fungal fermentation and co-hydrolysis to accumulate lipids could have the potential to enhance the utilization efficiency of lignocellulosic biomass for advanced biofuels production.
Seed management’s influences on nodulation and yield of improved variety of s...Agriculture Journal IJOEAR
Abstract— A pot study was carried out on an improved soybean variety (TGX 1448-2E) to assess the effects of seed management on its nodulation and yield. The experiment was in factorial combinations with six replicates at the teaching and research farm of University of Abuja. The factors were 2 soils, 2 levels of phosphorus fertilizer (-P and + P), and 2 seed sources (farmer’s and researcher’s managed seeds). P was applied as triple superphosphate at 30 kg P ha-1. Destructive sampling was done at 8 weeks after planting to record growth parameters and nodulation. At maturity, the number and weight of pods, weight of 50 seeds and total seed yield were recorded. The results showed that generally researchers’ managed seeds showed a significantly higher mean values than farmers’ managed seeds. The pod and total seed weight from researchers’ seeds were 106.26 g and 52.43 g per plant respectively against the farmers’ managed seed with pod weight of 80.23 g and total seed weight of 44.35 g per plant. P application influenced significantly the weight of nodules, pods and seeds per plant. This significant lower performance observed in farmers’ managed seeds could have resulted from factors such poor seed handling or mix up during harvesting or storage, poor quality seed selection for planting.
Indian agriculture feels the pain of fatigue of green revolution.
In the past 50 years, the fertilizer consumption exponentially increased from 0.5 (1960’s) to 24 million tonnes (2013) that commensurate with four-fold increase in food grain output (254 million tonnes) In order to achieve a target of 300 million tonnes of food grains and to feed the burgeoning population of 1.4 billion in 2025, the country will require 45 million tonnes of nutrients as against a current consumption level of 23 million tonnes. The sustainable agriculture and precision farming both are the urgent issues and hence the suitable agro-technological interventions are essential (e.g., nano and biotechnology) for ensuring the safety and sustainability of relevant production system.
Implementation of integrated pest management based on detrivore augmentation ...Innspub Net
Detrivore augmentation is a part of Integrated Pest Management (IPM) tactic based on local potential owned by farmers. Its main objective is to increase the abundance of decomposers organisms. Decomposers abundance is an indicator of the nutrient cycling availability. It also indicates the availability of alternative energy source that ensures the natural enemy populations. Augmentation efforts made through the addition of biomass include straw residue, Azolla sp., and organic fertilizers. Mutually with other IPM culture techniques applied, it can improve the abundance of soil arthropods by 9% during the dry season. Also there was an increasing by 15% at the wet season. Some taxa such as Araneae, Araneidae (orb-weaver spider) and Formicidae, which acts as a predator, have a significant increase in its population. A higher population was also observed in parasitic wasps, as well as in Collembola’s and Diptera’s: Chironomidae population, which acts as decomposers. In terms of the diversity index, there were no significant differences between sites (p = 0433; n = 48). However, the number of species, that is contributes to the community, is 1.4% higher in IPM site.
Presented by Barbara Gemmill-Herren during the seminar How to Feed Nine Billion within the Planet’s Boundaries - Agroecology for Food Security & Nutrition organised by the SIANI Expert group on Agriculture Transformation on March 10, 2015. Read more here: http://www.siani.se/expert-groups/agriculture-transformation-low-income-countries-under-environmental-change
Transformation of Sandalwood Leaves (Santalum album) into Nutrient Rich Compo...AI Publications
It is significant to use renewable resources to maximize crop yields and minimize the environmental risks accompanying with chemical residues. Composting is an age old practice for the biological conversion of organic waste into a humus-like substance which can enhance physical, chemical and biological soil properties. Vermicomposting of leaf litter by Eisenia foetida and Eudrilus eugenia potentially play a substantial role in remediation of organic waste as well as building up of soil fertility for sustainable agriculture. Present study was based on the conversion of Sandal wood leaf waste into nutrient rich best source. Sandal wood leaf were chopped at fine level and later mixed with cattle dung in order to pre composting followed by addition of earthworm.Several factors were also analysed during process. It was found that physical factors viz. pH, temperature moisture content etc. were significantly fluctuating at initial time period but later it was stagnant at constant level. Volume of waste and density were also reduced at the end of process. Colour of waste also turned into black that was good for seed germination but bad for health of earthworm. Final product was found odour less. Present results revealed about favourable condition of addition of earthworm into leaf litter waste and also explore the capability of both earthworm species to degrade leaf litter after semi-digested condition.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Siderophores are compounds from ancient Greek words, sidero ‘iron’ and phore ‘carriers’ meaning ‘iron carriers’. These are low-molecular-weight iron-chelating compounds, produced by ‘rhizospheric bacteria’ under iron-limited conditions. They are small, high affinity iron chelating compounds secreted by microorganisms such as bacteria, fungi etc. Siderophore usually form a stable hexahendate, octahedral complex with Fe3+.
An increasing number of businesses are starting up with social
and ethical as well as economic principles at the heart of what they do. This presentation, along with others you will see here, explores this theme.
Seed management’s influences on nodulation and yield of improved variety of s...Agriculture Journal IJOEAR
Abstract— A pot study was carried out on an improved soybean variety (TGX 1448-2E) to assess the effects of seed management on its nodulation and yield. The experiment was in factorial combinations with six replicates at the teaching and research farm of University of Abuja. The factors were 2 soils, 2 levels of phosphorus fertilizer (-P and + P), and 2 seed sources (farmer’s and researcher’s managed seeds). P was applied as triple superphosphate at 30 kg P ha-1. Destructive sampling was done at 8 weeks after planting to record growth parameters and nodulation. At maturity, the number and weight of pods, weight of 50 seeds and total seed yield were recorded. The results showed that generally researchers’ managed seeds showed a significantly higher mean values than farmers’ managed seeds. The pod and total seed weight from researchers’ seeds were 106.26 g and 52.43 g per plant respectively against the farmers’ managed seed with pod weight of 80.23 g and total seed weight of 44.35 g per plant. P application influenced significantly the weight of nodules, pods and seeds per plant. This significant lower performance observed in farmers’ managed seeds could have resulted from factors such poor seed handling or mix up during harvesting or storage, poor quality seed selection for planting.
Indian agriculture feels the pain of fatigue of green revolution.
In the past 50 years, the fertilizer consumption exponentially increased from 0.5 (1960’s) to 24 million tonnes (2013) that commensurate with four-fold increase in food grain output (254 million tonnes) In order to achieve a target of 300 million tonnes of food grains and to feed the burgeoning population of 1.4 billion in 2025, the country will require 45 million tonnes of nutrients as against a current consumption level of 23 million tonnes. The sustainable agriculture and precision farming both are the urgent issues and hence the suitable agro-technological interventions are essential (e.g., nano and biotechnology) for ensuring the safety and sustainability of relevant production system.
Implementation of integrated pest management based on detrivore augmentation ...Innspub Net
Detrivore augmentation is a part of Integrated Pest Management (IPM) tactic based on local potential owned by farmers. Its main objective is to increase the abundance of decomposers organisms. Decomposers abundance is an indicator of the nutrient cycling availability. It also indicates the availability of alternative energy source that ensures the natural enemy populations. Augmentation efforts made through the addition of biomass include straw residue, Azolla sp., and organic fertilizers. Mutually with other IPM culture techniques applied, it can improve the abundance of soil arthropods by 9% during the dry season. Also there was an increasing by 15% at the wet season. Some taxa such as Araneae, Araneidae (orb-weaver spider) and Formicidae, which acts as a predator, have a significant increase in its population. A higher population was also observed in parasitic wasps, as well as in Collembola’s and Diptera’s: Chironomidae population, which acts as decomposers. In terms of the diversity index, there were no significant differences between sites (p = 0433; n = 48). However, the number of species, that is contributes to the community, is 1.4% higher in IPM site.
Presented by Barbara Gemmill-Herren during the seminar How to Feed Nine Billion within the Planet’s Boundaries - Agroecology for Food Security & Nutrition organised by the SIANI Expert group on Agriculture Transformation on March 10, 2015. Read more here: http://www.siani.se/expert-groups/agriculture-transformation-low-income-countries-under-environmental-change
Transformation of Sandalwood Leaves (Santalum album) into Nutrient Rich Compo...AI Publications
It is significant to use renewable resources to maximize crop yields and minimize the environmental risks accompanying with chemical residues. Composting is an age old practice for the biological conversion of organic waste into a humus-like substance which can enhance physical, chemical and biological soil properties. Vermicomposting of leaf litter by Eisenia foetida and Eudrilus eugenia potentially play a substantial role in remediation of organic waste as well as building up of soil fertility for sustainable agriculture. Present study was based on the conversion of Sandal wood leaf waste into nutrient rich best source. Sandal wood leaf were chopped at fine level and later mixed with cattle dung in order to pre composting followed by addition of earthworm.Several factors were also analysed during process. It was found that physical factors viz. pH, temperature moisture content etc. were significantly fluctuating at initial time period but later it was stagnant at constant level. Volume of waste and density were also reduced at the end of process. Colour of waste also turned into black that was good for seed germination but bad for health of earthworm. Final product was found odour less. Present results revealed about favourable condition of addition of earthworm into leaf litter waste and also explore the capability of both earthworm species to degrade leaf litter after semi-digested condition.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Siderophores are compounds from ancient Greek words, sidero ‘iron’ and phore ‘carriers’ meaning ‘iron carriers’. These are low-molecular-weight iron-chelating compounds, produced by ‘rhizospheric bacteria’ under iron-limited conditions. They are small, high affinity iron chelating compounds secreted by microorganisms such as bacteria, fungi etc. Siderophore usually form a stable hexahendate, octahedral complex with Fe3+.
An increasing number of businesses are starting up with social
and ethical as well as economic principles at the heart of what they do. This presentation, along with others you will see here, explores this theme.
Levon Resources is exploring one of the world's largest silver resources at the company's 100%-owned Cordero Project in northwest Mexico. In less than four years, Levon has amassed a resource at Cordero containing 364M oz silver indicated plus 91M oz silver inferred. Further indicated resources of 945,000 oz gold, 6.1B lbs zinc and 3.3B lbs lead have established Cordero as one of Mexico's premier polymetallic porphyry targets.
Edgewater Exploration is a Canadian-based small cap mining company focused on building a portfolio of undervalued mid stage gold assets worldwide.
Edgewater has acquired the advanced stage Corcoesto gold asset through the acquisition of Rio Narcea Gold Mines in the Autonomous region of Galacia, Spain. The project is well located with excellent access to roads, power and a nearby local skilled workforce.
Copper Creek aggressively explores mineral projects that it feels have the potential for a world class mineral discovery. The company attempts to identify properties within prolific mining camps, with exploration targets that have been overlooked by previous operators, and that have the potential of quickly creating significant value for shareholders. The Bonsai project, in the Eskay Creek area of northern British Columbia, Canada and the Santa Lucia project in the Sierra Madre gold belt in Mexico are examples of this type of "high-impact" exploration project.
Comparative economic analysis of organic and inorganic wheatsanaullah noonari
The production of wheat crop for the year 2012-13 is estimated to be 24.2 million tons against last year’s
production of 23.4 million tons. The major reasons for this enhanced production were increase in support price
from Rs.1050 to Rs.1200 per 40 Kg which encouraged improved seed usage and fertilizers. There was also better
weather and comparatively more water available from the reservoirs. The target for wheat production for 2013-
14 has been fixed at 25.0 million tons. The fertilizer has raised the expenses of the inorganic farmers, which are
not, used in organic farming. Cash cost in case of organic and inorganic farming is Rs. 23053.00 and 25846.00
respectively. The non-cash cost of organic and inorganic are Rs.19389.65 and 18815.10 respectively. Total cost
is the combination of cash and non-cash costs that is Rs.42442.65 and 44661.00 in organic and inorganic
farming. Gross margin (GM) is obtained by subtracting the cash cost from the gross value of product. GM is
Rs.33142.65 and 36182.00 in organic and inorganic farming system. Net income is obtained by subtracting the
total cost from the gross value of product. It is Rs.13752.35 and Rs.17367.00 in organic and inorganic farming,
respectively showing a difference of Rs.2615.35. The analysis shows that low net income in organic farming
than the inorganic farming is due to the low yield and high labor cost in organic system. Secondly health and
environmental costs are not included in the analysis, because in the study site farmers are unaware of these costs.
Keywords: Wheat, organic, Inorganic, support price, environmental costs, Pakistan
Priorities for Public Sector Research on Food Security and Natural Resources, Review 2, Sara Scherr, Ecoagriculture Partners on April 12, 2013 at the Food Security Futures Conference in Dublin, Ireland.
Presented by: Norman Uphoff, CIIFAD, Cornell University, USA
Presented at: ECHO Conference on Asian Agriculture Chiangmai, Thailand
Presented on: September 21, 2009
Rice agroforestry: How trees can accelerate agroecological transitionsCIFOR-ICRAF
Presented by Fergus Sinclair, Rachmat Mulia, Himlal Baral,
Jim Roshetko, and Rob Finlayson
(CIFOR-ICRAF) at 6th International Rice Congress, Manila, Philippines, on 16-19 Oct 2023
Petrichor Energy - Petrichor Closes First Tranche Convertible Debenture Finan...Viral Network Inc
(October 1, 2013) – Petrichor Energy Inc. (FSE: YQN; TSX-V: PTP) (the “Company") announces that it closed the first tranche of its convertible debenture private placement (the "Private Placement") (refer to Press Releases April 3, 2013, June 7, 2013 and September 5, 2013). In accordance with the provisions of the subscription agreements received, at the closing of the Private Placement the Company issued convertible debentures in the total principal amount of C$3,400,000 (the “Debentures”).
Highbank is a Canadian aggregate exploration and development company. Highbank has earned a 100% interest in, and has obtained a NI 43-101 Resources evaluation of a +70 million tonne tidewater aggregate gravel tenure in northwestern British Columbia, Canada. The Company also holds a NSR interest in two moly/copper properties in Ireland.
Highbank Resources - Highbank Receives Comments on Notice of Work (NoW) Permi...Viral Network Inc
Highbank Resources Ltd. (the “Company”) (TSX Venture: HBK). Further to our news release on October 29, 2013, the Company has received review comments from the Ministry of Energy and Mines (“MEM”) indicating the results of MEM’s review and future expectations for this particular project in regards only to the Mines Act permitting.
Red Eagle Mining - Salman Partners "Accelerating Development at San Ramon-Pot...Viral Network Inc
Red Eagle Mining Corporation is an exploration company focused on advancing its wholly- owned San Ramon gold deposit, part of the Santa Rosa project in the Department of Antioquia, Colombia.
Golden Arrow Resources: Golden Arrow Triples Size of Chinchillas Silver ProjectViral Network Inc
Golden Arrow Resources Corporation (TSX-V: GRG, FRA: GAC (WKN: A0B6XQ), “Golden Arrow” or the “Company”) is pleased to announce the granting of additional concessions that surround the Chinchillas Project, effectively, tripling the area of the entire property to 1,160 hectares. The mining authority has granted the concessions as well as the drill permit for the newly acquired area.
Sierra Metals Inc. (formerly Dia Bras Exploration Inc.) is Latin America's newest mid-tier precious and base metals producer and offers a strong value proposition to investors based on:
1) Undervalued vs. Peers: Low cash cost producer with strong upside potential for growth.
2) A Solid Financial Position: Strong positive cash flow with $80 million in the treasury and $83 million in earnings during 2012.
3) Diversified Asset Base: Precious and base metals producer with three operating mines in Peru and Mexico.
4) Substantial Reserve Growth: Expanded Reserves 8x in two years; and, 30% annual production growth in 2012.
5) Stable Investment Yield: $10 million annual dividend plus share buyback program.
IntelGenx, through its cutting edge formulation platforms, has developed a broad and diverse product portfolio, including products for the treatment of severe depression, hypertension, erectile dysfunction, benign prostatic hyperplasia, migraine, insomnia, bipolar disorder, idiopathic pulmonary fibrosis, allergies and pain management.
Sierra Metals Inc. is a growing mid-tier precious and base metals producer in Latin America. The Company owns two low-cost mines in commercial production: the Yauricocha mine in Peru and the Bolivar mine in Mexico.
Sierra Metals Inc., formerly known as Dia Bras Exploration Inc., began exploration and development work in Mexico in early 2003. In 2004, the Company acquired the Bolivar mine property and began active development to advance the property towards production. In 2006, a rapid expansion into the Cusihuiriachic (“Cusi”) silver district resulted in the Company acquiring a 100 km2 property encompassing 12 former silver mines situated within a close proximity to the wholly owned Malpaso Mill. From 2006 to 2011 the Company shipped high-grade development ore for custom milling to the Malpasso Mill from the Bolivar project. Starting in 2009 the Company also started producing silver dore at the Malpaso Mill from development ore at the Cusi project.
In the spring of 2011, the Company expanded operations into Peru with the purchase of 82% of Sociedad Minera Corona S.A. (“Corona”) for a total purchase price of $286 million. Corona’s main asset is the Yauricocha mine in the Yauyos province in western central Peru. This purchase dramatically changed the production profile of Sierra Metals and excelled the Company from a junior exploration and development company to a mid-tier precious and base metals producer.
This rapid expansion in Peru was followed by the completion of the Piedras Verdes mill in Mexico and the announcement of commercial production at the Bolivar mine. Located 6 km from the Bolivar mine, the Piedras Verdes mill has a throughput capacity of 1,000 tpd with plans to expand to 2,000 tpd by mid-2013.
Sierra Metals is currently focused on expanding production at its Yauricocha and Bolivar mines and advancing its Cusi Property into commercial production. Additionally, the Company is completing an aggressive exploration and development programme to expand global reserves and resources and advance its pipeline of projects towards to production.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current company’s observability stack.
While the dev and ops silo continues to crumble….many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Le nuove frontiere dell'AI nell'RPA con UiPath Autopilot™UiPathCommunity
In questo evento online gratuito, organizzato dalla Community Italiana di UiPath, potrai esplorare le nuove funzionalità di Autopilot, il tool che integra l'Intelligenza Artificiale nei processi di sviluppo e utilizzo delle Automazioni.
📕 Vedremo insieme alcuni esempi dell'utilizzo di Autopilot in diversi tool della Suite UiPath:
Autopilot per Studio Web
Autopilot per Studio
Autopilot per Apps
Clipboard AI
GenAI applicata alla Document Understanding
👨🏫👨💻 Speakers:
Stefano Negro, UiPath MVPx3, RPA Tech Lead @ BSP Consultant
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Comparing the yields of Organic and Conventional Agriculture - Verena Seufert
1. LETTER doi:10.1038/nature11069
Comparing the yields of organic and conventional
agriculture
Verena Seufert1, Navin Ramankutty1 & Jonathan A. Foley2
Numerous reports have emphasized the need for major changes in Sixty-six studies met these criteria, representing 62 study sites, and
the global food system: agriculture must meet the twin challenge of reporting 316 organic-to-conventional yield comparisons on 34 dif-
feeding a growing population, with rising demand for meat and ferent crop species (Supplementary Table 4).
high-calorie diets, while simultaneously minimizing its global The average organic-to-conventional yield ratio from our meta-
environmental impacts1,2. Organic farming—a system aimed at analysis is 0.75 (with a 95% confidence interval of 0.71 to 0.79); that
producing food with minimal harm to ecosystems, animals or is, overall, organic yields are 25% lower than conventional (Fig. 1a).
humans—is often proposed as a solution3,4. However, critics argue This result only changes slightly (to a yield ratio of 0.74) when the
that organic agriculture may have lower yields and would therefore analysis is limited to studies following high scientific quality standards
need more land to produce the same amount of food as conven- (Fig. 2). When comparing organic and conventional yields it is important
tional farms, resulting in more widespread deforestation and bio-
diversity loss, and thus undermining the environmental benefits of
a
organic practices5. Here we use a comprehensive meta-analysis to Crop type
examine the relative yield performance of organic and conven- All crops (316)
tional farming systems globally. Our analysis of available data
Fruits (14)
shows that, overall, organic yields are typically lower than conven-
tional yields. But these yield differences are highly contextual, Oilseed crops (28)
depending on system and site characteristics, and range from 5%
lower organic yields (rain-fed legumes and perennials on weak- Cereals (161)
acidic to weak-alkaline soils), 13% lower yields (when best organic Vegetables (82)
practices are used), to 34% lower yields (when the conventional and
organic systems are most comparable). Under certain conditions— 0.4 0.6 0.8 1.0 1.2
that is, with good management practices, particular crop types and b
growing conditions—organic systems can thus nearly match con- Plant type
ventional yields, whereas under others it at present cannot. To Legumes (34)
establish organic agriculture as an important tool in sustainable
Non-legumes (282)
food production, the factors limiting organic yields need to be
more fully understood, alongside assessments of the many social,
environmental and economic benefits of organic farming systems.
Perennials (25)
Although yields are only part of a range of ecological, social and
economic benefits delivered by farming systems, it is widely accepted Annuals (291)
that high yields are central to sustainable food security on a finite land
basis1,2. Numerous individual studies have compared the yields of 0.4 0.6 0.8 1.0 1.2
organic and conventional farms, but few have attempted to synthesize c
this information on a global scale. A first study of this kind6 concluded Crop species
that organic agriculture matched, or even exceeded, conventional Maize (74)
yields, and could provide sufficient food on current agricultural land.
Barley (19)
However, this study was contested by a number of authors; the
criticisms included their use of data from crops not truly under organic Wheat (53)
management and inappropriate yield comparisons7,8.
We performed a comprehensive synthesis of the current scientific Tomato (35)
literature on organic-to-conventional yield comparisons using formal Soybean (25)
meta-analysis techniques. To address the criticisms of the previous
study6 we used several selection criteria: (1) we restricted our analysis 0.4 0.6 0.8 1.0 1.2
to studies of ‘truly’ organic systems, defined as those with certified Organic:conventional yield ratio
organic management or non-certified organic management, following
Figure 1 | Influence of different crop types, plant types and species on
the standards of organic certification bodies (see Supplementary
organic-to-conventional yield ratios. a–c, Influence of crop type (a), plant
Information); (2) we only included studies with comparable spatial type (b) and crop species (c) on organic-to-conventional yield ratios. Only those
and temporal scales for both organic and conventional systems (see crop types and crop species that were represented by at least ten observations
Methods); and (3) we only included studies reporting (or from which and two studies are shown. Values are mean effect sizes with 95% confidence
we could estimate) sample size and error. Conventional systems were intervals. The number of observations in each class is shown in parentheses. The
either high- or low-input commercial systems, or subsistence agriculture. dotted line indicates the cumulative effect size across all classes.
1
Department of Geography and Global Environmental and Climate Change Center, McGill University, Montreal, Quebec H2T 3A3, Canada. 2Institute on the Environment (IonE), University of Minnesota,
1954 Buford Avenue, St Paul, Minnesota 55108, USA.
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2. RESEARCH LETTER
to consider the food output per unit area and time, as organic rotations Sensitivity
often use more non-food crops like leguminous forage crops in their Best study quality (165)
rotations7. However, the meta-analysis suggests that studies using Non-food rotation (240)
longer periods of non-food crops in the organic rotation than conven-
Long-term studies (223)
tional systems do not differ in their yield ratio from studies using
similar periods of non-food crops (Fig. 2 and Supplementary Table 5). Typical conventional (167)
It thus appears that organic rotations do not require longer periods of
Comparable systems (64)
non-food crops, which is also corroborated by the fact that the majority
of studies (that is, 76%) use similar lengths of non-food crops in the Best org. management (76)
organic and conventional systems. Legumes and perennials (55)
The performance of organic systems varies substantially across crop
types and species (Fig. 1a–c; see Supplementary Table 5 for details on Best org. performance 1 (36)
categorical analysis). For example, yields of organic fruits and oilseed Best org. performance 2 (150)
crops show a small (23% and 211% respectively), but not statistically
significant, difference to conventional crops, whereas organic cereals 0.4 0.6 0.8 1
and vegetables have significantly lower yields than conventional crops Organic:conventional yield ratio
(226% and 233% respectively) (Fig. 1a). Figure 2 | Sensitivity study of organic-to-conventional yield ratios. Best
These differences seem to be related to the better organic perform- study quality, peer-reviewed studies using appropriate study design and
ance (referring to the relative yield of organic to conventional systems) making appropriate inferences; non-food rotation, studies where both systems
of perennial over annual crops and legumes over non-legumes have a similar duration of non-food crops; long-term studies, excludes very
(Fig. 1b). However, note that although legumes and perennials (and short duration and recently converted studies; typical conventional, restricted
fruits and oilseed crops) show statistically insignificant organic-to- to commercial conventional systems with yields comparable to local averages;
conventional yield differences, this is owing to the large uncertainty comparable systems, studies that use appropriate study design and make
range resulting from their relatively small sample size (n 5 34 for appropriate inferences, where both systems have the same non-food rotation
length and similar N inputs; best org. management, excludes studies without
legumes, n 5 25 for perennials, n 5 14 for fruits and n 5 28 for oilseed
best management practices or crop rotations; legumes and perennials,
crops; Fig. 1), and combining legumes and perennials reveals a signifi- restricted to leguminous and perennial crops; best org. performance 1, rain-fed
cant, but small, yield difference (Fig. 2). legumes and perennials on weak-acidic to weak-alkaline soils; best org.
Part of these yield responses can be explained by differences in the performance 2, rain-fed and weak-acidic to weak-alkaline soils. Values are
amount of nitrogen (N) input received by the two systems (Fig. 3a). mean effect sizes with 95% confidence intervals. The number of observations is
When organic systems receive higher quantities of N than conven- shown in parentheses. The dotted line indicates the effect size across all studies.
tional systems, organic performance improves, whereas conventional
systems do not benefit from more N. In other words, organic systems soil fertility and management skills13. This is supported by our analysis:
appear to be N limited, whereas conventional systems are not. Indeed, organic performance improves in studies that lasted for more than two
N availability has been found to be a major yield-limiting factor in seasons or were conducted on plots that had been organic for at least 3
many organic systems9. The release of plant-available mineral N from years (Fig. 2, Supplementary Fig. 5 and Supplementary Table 13).
organic sources such as cover crops, compost or animal manure is slow Water relations also influence organic yield ratios—organic per-
and often does not keep up with the high crop N demand during the formance is 235% under irrigated conditions, but only 217% under
peak growing period9,10. The better performance of organic legumes rain-fed conditions (Fig. 3e). This could be due to a relatively better
and perennials is not because they received more N, but rather because organic performance under variable moisture conditions in rain-fed
they seem to be more efficient at using N (Supplementary Table 7 and systems. Soils managed with organic methods have shown better
Supplementary Fig. 4). Legumes are not as dependent on external N water-holding capacity and water infiltration rates and have produced
sources as non-legumes, whereas perennials, owing to their longer higher yields than conventional systems under drought conditions and
growing period and extensive root systems, can achieve a better syn- excessive rainfall14,15 (see Supplementary Information). On the other
chrony between nutrient demands and the slow release of N from hand, organic systems are often nutrient limited (see earlier), and thus
organic matter11. probably do not respond as strongly to irrigation as conventional
Organic crops perform better on weak-acidic to weak-alkaline soils systems.
(that is, soils with a pH between 5.5. and 8.0; Fig. 3b). A possible The majority of studies in our meta-analysis come from developed
explanation is the difficulty of managing phosphorus (P) in organic countries (Supplementary Fig. 1). Comparing organic agriculture
systems. Under strongly alkaline and acidic conditions, P is less readily across the world, we find that in developed countries organic perform-
available to plants as it forms insoluble phosphates, and crops depend ance is, on average, 220%, whereas in developing countries it is 243%
to a stronger degree on soil amendments and fertilizers. Organic systems (Fig. 3f). This poor performance of organic agriculture in developing
often do not receive adequate P inputs to replenish the P lost through countries may be explained by the fact that a majority of the data (58 of
harvest12. To test this hypothesis we need further research on the 67 observations) from developing countries seem to have atypical con-
performance and nutrient dynamics of organic agriculture on soils ventional yields (.50% higher than local yield averages), coming from
of varying pH. irrigated lands (52 of 67), experimental stations (54 of 67) and from
Studies that reported having applied best management practices in systems not using best management practices (67 of 67; Supplementary
both systems show better organic performance (Fig. 3c). Nutrient and Fig. 10 and Supplementary Table 8). In the few cases from developing
pest management in organic systems rely on biological processes to countries where organic yields are compared to conventional yields
deliver plant nutrients and to control weed and herbivore populations. typical for the location or where the yield data comes from surveys,
Organic yields thus depend more on knowledge and good manage- organic yields do not differ significantly from conventional yields
ment practices than conventional yields. However, in organic systems because of a wide confidence interval resulting from the small sample
that are not N limited (as they grow perennial or leguminous crops, or size (n 5 8 and n 5 12 respectively, Supplementary Fig. 10a).
apply large N inputs), best management practices are not required The results of our meta-analysis differ dramatically from previous
(Supplementary Table 11). results6. Although our organic performance estimate is lower than
It is often reported that organic yields are low in the first years after previously reported6 in developed countries (220% compared to
conversion and gradually increase over time, owing to improvements in 28%), our results are markedly different in developing countries
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3. LETTER RESEARCH
a b do not. Improvements in management techniques that address factors
N input amount Soil pH limiting yields in organic systems and/or the adoption of organic agri-
More in organic (64) Strong acidic (57) culture under those agroecological conditions where it performs best
Similar (71) Weak acidic to weak may be able to close the gap between organic and conventional yields.
More in conventional
alkaline (216) Although we were able to identify some factors contributing to varia-
(103) Strong alkaline (37) tions in organic performance, several other potentially important factors
0.4 0.6 0.8 1.0 0.4 0.6 0.8 1.0 could not be tested owing to a lack of appropriate studies. For example,
we were unable to analyse tillage, crop residue or pest management.
c d Also, most studies included in our analysis experienced favourable grow-
BMP Time since conversion
Recent (141)
ing conditions (Supplementary Fig. 8), and organic systems were mostly
No BMP (235) compared to commercial high-input systems (which had predominantly
Young (34) above-average yields in developing countries; Supplementary Figs 6b
BMP used (81)
Established (27) and 10a). In addition, it would be desirable to examine the total
human-edible calorie or net energy yield of the entire farm system rather
0.4 0.6 0.8 1.0 0.4 0.6 0.8 1.0 than the biomass yield of a single crop species. To understand better the
performance of organic agriculture, we should: (1) systematically analyse
e f the long-term performance of organic agriculture under different
Irrigation Country development
management regimes; (2) study organic systems under a wider range
Irrigated (125) Developed (249) of biophysical conditions; (3) examine the relative yield performance of
smallholder agricultural systems; and (4) evaluate the performance of
Developing (67)
Rain-fed (191) farming systems through more holistic system metrics.
0.4 0.6 0.8 1.0
As emphasized earlier, yields are only part of a range of economic,
0.4 0.6 0.8 1.0
Organic:conventional yield ratio
social and environmental factors that should be considered when
Organic:conventional yield ratio
gauging the benefits of different farming systems. In developed countries,
Figure 3 | Influence of N input, soil pH, best management practices, time the central question is whether the environmental benefits of organic
since conversion to organic management, irrigation and country crop production would offset the costs of lower yields (such as increased
development. a–f, Influence of the amount of N input (a), soil pH (b), the use of food prices and reduced food exports). Although several studies have
best management practices (BMP; c), time since conversion to organic
suggested that organic agriculture can have a reduced environmental
management (d), irrigation (e) and country development (f) on organic-to-
conventional yield ratios. For details on the definition of categorical variables see impact compared to conventional agriculture18,19, the environmental
Supplementary Tables 1–3. Values are mean effect sizes with 95% confidence performance of organic agriculture per unit output or per unit input
intervals. The number of observations in each class is shown in parentheses. The may not always be advantageous20,21. In developing countries, a key
dotted line indicates the cumulative effect size across all classes. question is whether organic agriculture can help alleviate poverty for
small farmers and increase food security. On the one hand, it has been
(243% compared to 180%). This is because the previous analysis suggested that organic agriculture may improve farmer livelihoods
mainly included yield comparisons from conventional low-input sub- owing to cheaper inputs, higher and more stable prices, and risk diver-
sistence systems, whereas our data set mainly includes data from high- sification16. On the other hand, organic agriculture in developing
input systems for developing countries. However, the previous study countries is often an export-oriented system tied to a certification
compared subsistence systems to yields that were not truly organic, process by international bodies, and its profitability can vary between
and/or from surveys of projects that lacked an adequate control. Not a locations and years22,23.
single study comparing organic to subsistence systems met our selec- There are many factors to consider in balancing the benefits of
tion criteria and could be included in the meta-analysis. We cannot, organic and conventional agriculture, and there are no simple ways
therefore, rule out the claim16 that organic agriculture can increase to determine a clear ‘winner’ for all possible farming situations.
yields in smallholder agriculture in developing countries. But owing However, instead of continuing the ideologically charged ‘organic
to a lack of quantitative studies with appropriate controls we do not versus conventional’ debate, we should systematically evaluate the
have sufficient scientific evidence to support it either. Fortunately, the costs and benefits of different management options. In the end, to
Swiss Research Institute of Organic Agriculture (FiBL) recently estab- achieve sustainable food security we will probably need many different
lished the first long-term comparison of organic and different conven- techniques—including organic, conventional, and possible ‘hybrid’
tional systems in the tropics17. Such well-designed long-term field trials systems24—to produce more food at affordable prices, ensure liveli-
are urgently needed. hoods for farmers, and reduce the environmental costs of agriculture.
Our analysis shows that yield differences between organic and con-
ventional agriculture do exist, but that they are highly contextual. METHODS SUMMARY
When using best organic management practices yields are closer to We conducted a comprehensive literature search, compiling scientific studies
(213%) conventional yields (Fig. 2). Organic agriculture also performs comparing organic to conventional yields that met our selection criteria. We
better under certain agroecological conditions—for example, organic minimized the use of selection criteria based on judgments of study quality but
legumes or perennials, on weak-acidic to weak-alkaline soils, in rain- examined its influence in the categorical analysis. We collected information on
fed conditions, achieve yields that are only 5% lower than conventional several study characteristics reported in the papers and derived characteristics of
yields (Fig. 2). On the other hand, when only the most comparable the study site from spatial global data sets (see Supplementary Tables 1–3 for a
conventional and organic systems are considered the yield difference is description of all categorical variables). We examined the difference between
as high as 34% (Fig. 2). In developed countries or in studies that use organic and conventional yields with the natural logarithm of the response ratio
conventional yields that are representative of regional averages, the (the ratio between organic and conventional yields), an effect size commonly used
in meta-analyses25. To calculate the cumulative effect size we weighted each indi-
yield difference between comparable organic and conventional systems,
vidual observation by the inverse of the mixed-model variance. Such a categorical
however, goes down to 8% and 13%, respectively (see Supplementary meta-analysis should be used when the data have some underlying structure and
Information). individual observations can be categorized into groups (for example, crop species
In short, these results suggest that today’s organic systems may or fertilization practices)26. An effect size is considered significant if its confidence
nearly rival conventional yields in some cases—with particular crop interval does not overlap with 1 in the back-transformed response ratio. To test the
types, growing conditions and management practices—but often they influence of categorical variables on yield effect sizes we examined between-group
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4. RESEARCH LETTER
heterogeneity (QB). A significant QB indicates that there are differences in effect 16. Scialabba, N. & Hattam, C. Organic Agriculture, Environment and Food Security (Food
sizes between different classes of a categorical variable26. All statistical analyses and Agriculture Organization, 2002).
17. Research Institute of Organic Agriculture (FiBL). Farming System Comparison in the
were carried out in MetaWin 2.026. Tropics http://www.systems-comparison.fibl.org/ (2011).
Full Methods and any associated references are available in the online version of 18. Crowder, D. W., Northfield, T. D., Strand, M. R. & Snyder, W. E. Organic agriculture
the paper at www.nature.com/nature. promotes evenness and natural pest control. Nature 466, 109–112 (2010).
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19. Bengtsson, J., Ahnstro J. & Weibull, A.-C. The effects of organic agriculture on
biodiversity and abundance: a meta-analysis. J. Appl. Ecol. 42, 261–269 (2005).
Received 6 November 2011; accepted 9 March 2012. ¨m,
20. Kirchmann, H. & Bergstro L. Do organic farming practices reduce nitrate
Published online 25 April 2012. leaching? Commun. Soil Sci. Plan. 32, 997–1028 (2001).
21. Leifeld, J. & Fuhrer, J. Organic farming and soil carbon sequestration: what do we
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http://www2.ohchr.org/ english/issues/food/docs/A-HRC-16–49.pdf (United 25. Hedges, L. V., Gurevitch, J. & Curtis, P. S. The meta-analysis of response ratios in
Nations, 2010). experimental ecology. Ecology 80, 1150–1156 (1999).
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6. Badgley, C. et al. Organic agriculture and the global food supply. Renew. Agr. Food analysis: Version 2 (Sinauer, 2000).
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7. Cassman, K. G. Editorial response by Kenneth Cassman: can organic agriculture Supplementary Information is linked to the online version of the paper at
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8. Connor, D. J. Organic agriculture cannot feed the world. Field Crops Res. 106,
187–190 (2008). Acknowledgements We are grateful to the authors of the 66 studies whose extensive
field work provided the data for this meta-analysis. Owing to space limitations our
9. Berry, P. et al. Is the productivity of organic farms restricted by the supply of
available nitrogen? Soil Use Manage. 18, 248–255 (2002). citations can be found in Supplementary Material. We would like to thank J. Reganold
10. Pang, X. & Letey, J. Organic farming: challenge of timing nitrogen availability to for useful comments on our manuscript. We are grateful to I. Perfecto, T. Moore,
crop nitrogen requirements. Soil Sci. Soc. Am. J. 64, 247–253 (2000). C. Halpenny, G. Seufert and S. Lehringer for valuable discussion and/or feedback on the
11. Crews, T. E. & Peoples, M. B. Can the synchrony of nitrogen supply and crop manuscript and L. Gunst for sharing publications on the FiBL trials. D. Plouffe helped
with the figures and M. Henry with compiling data. This research was supported by a
demand be improved in legume and fertilizer-based agroecosystems? A review.
Nutr. Cycl. Agroecosyst. 72, 101–120 (2005). Discovery Grant awarded to N.R. from the Natural Science and Engineering Research
12. Oehl, F. et al. Phosphorus budget and phosphorus availability in soils under Council of Canada.
organic and conventional farming. Nutr. Cycl. Agroecosyst. 62, 25–35 (2002). Author Contributions V.S. and N.R. designed the study. V.S. compiled the data and
13. Martini, E., Buyer, J. S., Bryant, D. C., Hartz, T. K. & Denison, R. F. Yield increases carried out data analysis. All authors discussed the results and contributed to writing
during the organic transition: improving soil quality or increasing experience? the paper.
Field Crops Res. 86, 255–266 (2004).
14. Letter, D., Seidel, R. & Liebhardt, W. The performance of organic and conventional Author Information Reprints and permissions information is available at
cropping systems in an extreme climate year. Am. J. Altern. Agric. 18, 146–154 www.nature.com/reprints. The authors declare no competing financial interests.
(2003). Readers are welcome to comment on the online version of this article at
15. Colla, G. et al. Soil physical properties and tomato yield and quality in alternative www.nature.com/nature. Correspondence and requests for materials should be
cropping systems. Agron. J. 92, 924–932 (2000). addressed to V.S. (verena.seufert@mail.mcgill.ca).
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5. LETTER RESEARCH
METHODS in the studies and we only derived soil pH values from the global data set if no soil pH
Literature search. We searched the literature on studies reporting organic-to- value was indicated in the paper.
conventional yield comparisons. First we used the references included in the To assess whether the conventional yield values reported by studies and
previous study6 and then extended the search by using online search engines included in the meta-analysis were representative of regional average crop yields,
(Google scholar, ISI web of knowledge) as well as reference lists of published we compared them to FAOSTAT yield data and a high-resolution spatial yield
articles. We applied several selection criteria to address the criticisms of the pre- data set34,35. We used the FAO data35, which reports national yearly crop yields
vious study6 and to ensure that minimum scientific standards were met. Studies from 1961 to 2009, for temporal detail and a yield data set34, which reports sub-
were only included if they (1) reported yield data on individual crop species in an national crop yields for 175 crops for the year 2000 at a 5-min latitude by 5-min
organic treatment and a conventional treatment, (2) the organic treatment was longitude resolution, for spatial detail. We calculated country average crop yields
truly organic (that is, either certified organic or following organic standards), (3) from FAO data for the respective study period and calculated the ratio of this
reported primary data, (4) the scale of the organic and conventional yield observa- average study-period yield to the year-2000 FAO national yield value. We derived
tions were comparable, (5) data were not already included from another paper the year-2000 yield value from the spatial data set through the latitude by longitude
(that is, avoid multiple counting), and (6) reported the mean (X), an error term value of the study site and scaled this value to the study-period-to-year-2000 ratio
(standard deviation (s.d.), standard error (s.e.) or confidence interval) and sample from FAOSTAT. If the meta-analysis conventional yield value was more than 50%
size (n) as numerical or graphical data, or if X and s.d. of yields over time could be higher than the local yield average derived by this method it was classified as ‘above
calculated from the reported data. For organic and conventional treatments to be average’, when it was more than 50% lower as ‘below average’, and when it was
considered comparable, the temporal and spatial scale of the reported yields within 650% of local yield averages as ‘comparable’. We choose this large yield
needed to be the same, that is, national averages of conventional agriculture difference as a threshold to account for uncertainties in the FAOSTAT and global
compared to national averages of organic agriculture or yields on an organic farm yield data set34.
compared to yields on a neighbouring conventional farm—not included were, for Meta-analysis. The natural log of the response ratio25 was used as an effect size
example, single farm yields compared to national or regional averages or before– metric for the meta-analysis. The response ratio is calculated as the ratio between
after comparisons. Previous studies27 have illustrated the danger of comparing the organic and the conventional yield. The use of the natural logarithm linearizes
yield data drawn from single plots and field trials to larger state and national the metric (treating deviations in the numerator and the denominator the same)
averages. and provides more normal sampling distribution in small samples25. If the data set
The use of selection criteria is a critical step in conducting a meta-analysis. On the has some underlying structure and studies can be categorized into more than one
one hand, scientific quality and comparability of observations needs to be ensured. group (for example, different crop species, or different fertilizer types) a categorical
On the other hand, a meta-analysis should provide as complete a summary of the meta-analysis can be conducted26. Observations with the same or similar
current research as possible. There is an ongoing debate about whether meta- management or system characteristics were grouped together. We then used a
analyses should adopt very specific selection criteria to prevent mixing incompar- mixed effects model to partition the variance of the sample, assuming that there is
able data sets together and to minimize variation in the data set28 or whether, random variation within a group and fixed variation between groups. We calcu-
instead, meta-analyses should include as wide a range of studies as possible to allow lated a cumulative effect size as weighted mean from all studies by weighting each
for an analysis of sources of variation29. We followed the generally recommended individual observation by the reciprocal of the mixed-model variance, which is the
approach, trying to minimize the use of selection criteria based on judgments of sum of the study sampling variance and the pooled within-group variance.
study quality30. Instead, we examined the influence of quality criteria empirically by Weighted parametric meta-analysis should be used whenever possible to deal with
evaluating the differences between observations with different quality standards. heteroscedasticity in the sample and to increase the statistical power of the ana-
We did not therefore exclude yield observations from non-peer-reviewed sources or lysis36. The cumulative effect size is considered to be significantly different from
from studies that lacked an appropriate experimental design a priori. The quality of zero (that is, the organic treatment shows a significant effect on crop yield) if its
the study and the comparability of the organic and conventional systems were 95% confidence interval does not overlap zero.
assessed by evaluating the experimental design of the study as well as the form of To test for differences in the effect sizes between groups the total heterogeneity
publication. Studies that were published in peer-reviewed journals and that con- of the sample was partitioned into the within group (QW) and between group
trolled for the possible influence of variability in space and time on experimental heterogeneity (QB) in a process similar to an analysis of variance37. The signifi-
outcomes through an appropriate experimental design were considered to follow cance of QB was tested by comparing it against the critical value of the x2 distri-
high quality standards.
bution. A significant QB implies that there are differences among cumulative effect
Categorical variables. In addition to study quality criteria, information on several
sizes between groups26,38. Only those effects that showed a significant QB are
other study characteristics like crop species, location and timescale, and on dif-
presented in graphs. All statistical analyses were carried out using MetaWin
ferent management practices, was collected (see Supplementary Tables 1–3). We
2.026. For representation in graphs effect sizes were back-transformed to response
also wanted to test the effect of study site characteristics on yield ratios and we thus
ratios.
collected information on biophysical characteristics of the study site. As most
Each observation in a meta-analysis is required to be independent. Repeated
studies did not report climate or soil variables we derived information on several
measurements in the same location over time are not independent. If yield values
agroecological variables that capture cropland suitability31, including the moisture
index a (the ratio of actual to potential evapotranspiration) as an indicator of from a single experiment were reported over several years therefore the average
moisture availability to crops, growing degree days (GDD, the annual sum of daily yield over time was calculated and used in the meta-analysis. If the mean and
mean temperatures over a base temperature of 5 uC) as an indicator of growing variance of multiple years was reported, the weighted average over time was
season length, as well as soil carbon density (Csoil, as a measure of soil organic calculated by weighting each year by the inverse of its variance. Different experi-
content) and soil pH as indicators of soil quality from the latitude 3 longitude ments (for example, different tillage practices, crop species or fertilizer rates) from
values of the study site and global spatial models/data sets at 5 min resolution32,33. the same study are not necessarily independent. However, it is recommended to
We derived the thresholds for the classification of these climate and soil vari- still include different experiments from the same study, as their omission would
ables from the probability of cultivation functions previously described31. This cause more distortions of the results than the lack of true independence38. We
probability of cultivation function is a curve fitted to the empirical relationship therefore included different experiments from a single study separately in the
between cropland areas, a, GDD or Csoil. It describes the probability that a location meta-analysis.
with a certain climate or soil characteristic is covered by cropland. Suitable loca- If data from the same experiment from the same study period were reported in
tions with favourable climate and soil characteristics have a higher probability of several papers, the data were only included once, namely from the paper that
being cultivated. Favourable climate and soil characteristics can thus be inferred reported the data in the highest detail (that is, reporting s.e./s.e. and n and/or
from the probability of cultivation. For a, GDD and Csoil a probability of cultiva- reporting the longest time period). If instead data from the same experiment from
tion under 30% was classified as ‘low’ suitability, between 30% and 70% as different years were reported in separate papers, the data were included separately
‘medium’ suitability, and above 70% as ‘high’ suitability (Supplementary Table 3). in the analysis (for example, refs 39, 40).
Sites with low and medium suitable moisture indices are interpreted as having In addition to potential within-study dependence of effect size data, there can
insufficient water availability, sites with low and medium GDD have short growing also be issues with between-study dependence of data36—data from studies con-
seasons, and sites with low and medium soil carbon densities are either unfertile ducted by the same author, in the same location or on the same crop species are
because they have too small a Csoil and low organic matter content (and thus also potentially non-independent. We addressed this issue by conducting a hier-
insufficient nutrients) or too high a Csoil in soils in wetlands where organic matter archical, categorical meta-analysis (as described earlier), specifically testing for the
accumulates because they are submerged under water. For soil pH, instead, we influence of numerous moderators on the effect size. In addition, we examined the
defined thresholds based on expert judgment. Soil pH information was often given interaction between categorical variables through a combination of contingency
6. RESEARCH LETTER
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