BACKGROUND AND OBJECTIVES
The use of chemical fertilizers in crop production is at the center of managing food security and environmental challenges. Increasing crop yields through increased fertilizer use is essential to meeting current as well as future food demands. Nevertheless, fertilizer application in croplands is a major source of anthropogenic greenhouse gas (GHG) – reducing GHG emissions through proper fertilizer management is essential to addressing agriculture’s contributions to climate change. Moreover, excess and improper use of nutrients in crop production have large cost implications for farmers. Improving nutrient use efficiency (NUE) in croplands not only increases food production but also helps adaptation to and mitigation of climate change.
The Indian food system feeds 18% of the human population and 15% of livestock population globally, and consumes about one-fifth of global fertilizer. Proper fertilizer management in Indian food systems is of global importance both for food security and environmental sustainability. NUE of Indian food production is the lowest in the world, mainly due to blanket fertilization practices, but there are opportunities to improve NUE, increase yields and profitability, and minimize negative environmental consequences. In this initiative, we demonstrated how nutrient management through the use of digital tools, such as the Nutrient Expert (NE) decision support tool, can boost rice and wheat productivity and increase farmers’ income, while reducing chemical fertilizer use and GHG emissions.
NE is an easy-to-use interactive computer-based decision tool that can rapidly provide nutrient recommendation for individual farmers’ fields in the presence or absence of soil testing data. NE estimates the attainable yield for a farmer’s field based on the
growing conditions, determines the nutrient balance in the cropping system based on yield and fertilizer/manure applied in the
previous crop, and combines such information with soil characteristics to predict expected N, P, and K response in the concerned
field to generate a location specific nutrient recommendation.
Led by the International Maize and Wheat Improvement Center (CIMMYT) in partnership with the Borlaug Institute for South Asia
(BISA), the International Rice Research Institute (IRRI), CGIAR Research Program on Climate Change, Agriculture and Food
Security (CCAFS), Indian Council of Agricultural Research (ICAR), Alliance CIAT- Biodiversity, former International Plant Nutrition
Institute (IPNI), and African Plant Nutrition Institute (APNI), researchers tested the NE decision tool against typical farmer fertilization
practices using approximately 1,600 side-by-side comparison trials in rice and wheat fields across the Indo-Gangetic Plains over a period of four years. Of these, 730 and 864 trials were conducted on rice and wheat, respectively. The plot size ranged from 1,000 to 2,000 m2 in Haryana and Punjab, and from 500 to 1,500 m2 in Bihar. All practices, except fertilizer management, were similar in the comparison trials. Although the participating farmers primarily managed the plots, researchers collected relevant crop management data, combined them with relevant soil and climatic data, and compared the outputs of farmers’ fertilizing practices with NE-based fertilizer management in terms of crop yield, cost of production, net return, and environmental footprint, calculating NE-based recommendations using the Nutrient Expert® tool.
Project impacts on sustainable development include:
Social: The majority of participating farmers achieved yield gains and increased their farm income by adopting NE-based fertilizer recommendations when compared with farmers’ existing fertilizer management practices. Although the effect of NE on crop yield increases is significantly influenced by the crop type, agro-ecology, soil properties, and farmers’ current level of fertilization, adoption of this practice in all rice and wheat acreage in India would result in additional production of 8.5 and 5.4 million tons of rice and wheat, respectively, without incurring additional production costs.
Environmental: The study found that NE-based recommendations lowered GHG emissions by 12- 20% in wheat and by around 2.5% in rice as compared with conventional fertilization practices. If these GHG emissions reductions of 2.5% in rice and 20% in wheat due to NE-based fertilizer management practices could be achieved in all rice and wheat areas in India, this would translate into GHG cuts of 5.2 million tons CO2e, i.e., 0.61 million tons of CO2e from rice and 4.63 million tons of CO2e from wheat.
Economic: The use of the NE tool resulted in reduced N application in all cases. Estimated N fertilizer savings due to NE-based fertilizer management in rice and wheat in India will be about 1.44 million tons, which would have major implications on costs and GHG emission cuts. Adoption of the NE tool reduced phosphorus application in some cases, although potash application increased in most cases, resulting in both positive and negative impacts on total cost of fertilizer use. In cases where yield gain was obtained due to increased fertilizer use, the increase in fertilizer cost was compensated by the yield gains. Many farmers have achieved double gains, i.e. decrease in fertilizer cost as well as yield gains.
SUCCESSES AND LESSONS LEARNED
Each farmer’s field is different, which is why blanket fertilizer recommendations are not always effective in producing better yields. By using nutrient management tools such as NE, farmers can obtain fertilizer recommendations specific to their field and economic conditions and thus avoid under-fertilizing or over-fertilizing. In smallholder production systems of South Asia such as India, which has diverse soil conditions, nutrient recommendation based on soil tests are financially and logistically impossible. Therefore, a decision support tool such as NE could be an important factor for implementing site-specific nutrient management recommendations that account for each field’s nutrient supplying capacity.
Given the magnitude of potential implications in terms of increasing yields, reducing fertilizer consumption and GHG emissions, governments need to consider scaling out NE-based fertilizer management by enabling policies and institutional arrangements. Implementation of NE at field level requires some level of technical knowledge to run this tool via computer or smartphone. Given this requirement, the technology is best scaled-up through the network of government extension systems, leader farmers, and civil society organizations working directly with farmers.