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Evaluating the Impact of Flood-Resistant Rice on Fertilizer Use and Crop Yield in India

Development Challenge

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.  Smallholder farmers in developing countries are particularly at risk 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. 


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 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. The Swarna-Sub1 rice variety has not yet been adopted in Orissa, allowing for a randomized evaluation.

Evaluation Strategy

The primary goal of this study is to evaluate the impact of Swarna-Sub1 on crop yield and use of more productive inputs due to risk reduction. The researchers will: (1) evaluate the effect of this risk-reduction technology on the usage of fertilizer and other production inputs, and; (2) evaluate the subsequent effect of reduced risk on improvements in fertilizer management techniques (3) evaluate whether introduction of Swarna-Sub1 induces farmers to “dis-adopt” traditional rice varieties that survive extreme flooding but produce low yields under normal conditions.

The researchers are conducting a randomized evaluation in 128 villages in Balasore and Bhadrak districts of Orissa.  64 villages have been randomly assigned to a treatment group and another 64 villages comprise a comparison group.   In the treatment group, five farmers in each village have been randomly selected to receive a start-up kit consisting of 5 kg of the new seed.  The comparison villages receive no intervention.  After the first year of harvest, the farmers are instructed to diffuse the new seeds, allowing the Swarna-Sub1 variety to multiply over subsequent seasons.

The outcome variables of fertilizer use will be evaluated at three points in time. The first post-harvest survey began in March 2012, and serves to measure both the yield returns to the Swarna-Sub1 technology in the first year of harvest, and to collect information about improvements in fertilizer use and management practices.  Measurement of returns under flooding conditions will be possible since approximately 50 percent of treatment villages were affected by flooding during September 2011.  A second post-harvest survey is scheduled for February 2013.  Any changes in management behavior will likely start to be observed at this time given that farmers have multiplied the seed and observed its ability to outperform the existing technology under flooding conditions.  An additional post-harvest survey will be completed after the wet season 2013 harvest in March 2014.   

Results and Policy Implications

In areas flooded up to two weeks, Swarna-Sub1 has a clear advantage over Swarna. With each additional day of flooding, Swarna-Sub1 avoids a loss in production of approximately 64 kilograms per hectare relative to Swarna, the next best variety. After 13 days of flooding, Swarna-Sub1 yields are 718 kilograms per hectare or 66 percent more than Swarna. Importantly, there is also no difference in yields between the two varities in non-flooded areas.

Scheduled Caste or Scheduled Tribe farmers – who disproportionately cultivate land in flood-prone areas – on average experience 1.83 more days of flooding than higher caste. Researchers predict 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, therefore, suggest that the widespread adoption of Swarna-Sub1 can increase yields of all farmers, with the poorest and most marginalized farmers benefiting the most. 

Additionally, among farmers who switched to Swarna-Sub1, up to 41 percent of the increase in gains was a result of the increased investment in other productive assets. As Swarna-Sub1 protects farmers against the risk of unpredictable flooding, they were more willing to invest in other productive inputs. The changes to farmer behavior include an 11 percent increase in fertilizer use, shifts away from less productive traditional seeds, adoption of a more productive planting technique, a 9-10 percent increase in the area of land cultivated, increased use of agricultural credit products, and lower precautionary savings. These shifts to more productive behavior indicate that stress-tolerant crops mitigate a substantial risk and allow farmers to make choices, previously considered too risky, that can increase productivity, yields, and ultimately profits.


2011 - Ongoing.