Adoption of Improved Fertilizer Management Practices Under Risk Reduction Due to Submergence-tolerant Rice

(IRRI Photo/Adam Barclay CPS)

Climate change poses a critical challenge to farmers, as extreme weather patterns increase both the likelihood of crop destruction due to drought or flooding, and variability in output levels. Researchers partnered with CGIAR’s International Rice Research Institute (IRRI) to evaluate the impact of a flood-resistant rice variety on fertilizer use and crop yield in Orissa, India. During floods, the flood tolerant seeds had a clear advantage over the traditional seeds. In non-flooded areas, there was no significant difference in yields between flood-resistant and traditional seeds, suggesting that there was no yield penalty in non-flood years to farmers who switched to the new seed technology.

Policy Issue 

Smallholder farmers in developing countries are particularly at risk from climate change because they have fewer resources to cope with unexpected weather shocks. Crop losses can significantly reduce household income, limiting investment in nutrition, health care, and education, with long-term negative consequences for human capital formation and the ability to escape the inter-generational transfer of poverty. Further, crop loss limits the expected benefit from investments in agricultural inputs such as fertilizer. In response, farmers invest less in fertilizer inputs if their fields are prone to flooding or their area to drought. Such risk-management measures result in lower crop yields even during seasons of average rainfall.

Context of the Evaluation 

One innovation designed to mitigate increased risk imposed by climate change is flood-resistant crop varieties. Researchers from the Consultative Group on International Agricultural Research (CGIAR) have experimented with crossbreeding rice varieties. In their tests, a flood-resistant gene called Sub1 is inserted into the popular Swarna rice variety to create the Swarna-Sub1 variety. Swarna-Sub1 rice is resilient to flood submergence for up to two to three weeks, thereby reducing risk and providing a higher yield potential for farmers. This variety presents a milestone as the first instance of the use of gene crossing to create a stress-tolerant staple grain in a developing country. The Sub1 gene has also been inserted into other popular rice varieties grown by farmers. The success of this new technology has important implications for rice cultivation across South Asia and Africa.

This project evaluates the impact of introducing the Swarna-Sub1 rice variety in the Indian state of Orissa. In this region, rice is a staple food and risk of flooding is high. Low levels of fertilizer use are characteristic of flood-prone areas of India.

Details of the Intervention 

Researchers partnered with CGIAR’s International Rice Research Institute (IRRI) to evaluate the impact of Swarna-Sub1 on (1) usage of fertilizer and other production inputs; (2) improvements in fertilizer management techniques and crop yield; and (3) whether the introduction of Swarna-Sub1 induces farmers to “disadopt” traditional rice varieties that survive extreme flooding but produce low yields under normal conditions.

The researchers randomly assigned 64 villages to receive the flood-tolerant seeds (treatment group) and another 64 villages to receive nothing (comparison group). Five farmers in each of the 64 villages were then randomly selected to receive a start-up kit consisting of 5 kg of the new seed. After the first year of harvest, the farmers were instructed to diffuse the new seeds, allowing the Swarna-Sub1 variety to multiply over subsequent seasons. These farmers are expected to keep seeds for planting and sell seeds to others.

Results and Policy Lessons 

During floods, the flood tolerant seeds (Swarna-Sub1) had a clear advantage over the traditional seeds (Swarna). With each additional day of flooding, Swarna-Sub1 avoided a loss in production of approximately 64 kilograms per hectare relative to Swarna. The yield advantage of Swarna-Sub1 increased as flood severity worsens, with a maximum advantage of around 718 kg per hectare over 13 days of flooding, an approximately 66 percent increase over traditional Swarna varieties. In non-flooded areas, there was no significant difference in yields between Swarna and Swarna-Sub1, suggesting that there is no yield penalty in non-flood years to farmers who switch to Swarna-Sub1.

Researchers also examined which social groups were most likely to realize the benefits of flood tolerant rice by identifying who cultivated land exposed to flooding. Scheduled Caste or Scheduled Tribe farmers, belonging to two of the most disadvantaged groups in India, experienced an average of 1.83 more days of flooding than higher caste farmers. Researchers predicted that if all farmers in the flooded sample area had used Swarna-Sub1, yields would have increased by 24.8 percent among the higher caste farmers and by 39.6 percent among Scheduled Caste/Scheduled Tribe farmers. The results suggest that the widespread adoption of Swarna-Sub1 could increase yields of all farmers, with the poorest and most marginalized farmers benefiting the most.

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