In the spirit of science, we should ask why studies don't reflect farmers' experiences.I read the News Feature “Feast or famine?” (Nature 428, 360–361; 2004) with great interest, because I have been responsible for introducing the System of Rice Intensification (SRI) in the Indian state of Andhra Pradesh since the summer season of 2003. The experiences of farmers are quite different from what is reported by sceptical scientists.
SRI results are not “a miracle”; they are quite explainable. Planting young seedlings carefully and at wider spacing gives the plant more time and space for tillering and root growth. Careful water management, keeping the field wet and not flooded, gives better yield because it supports healthy root growth.
This practice should be encouraged everywhere, as the whole world is facing water shortages. Weeding rice fields with a rotary weeder helps by churning the soil and incorporating the weed biomass as it aerates the root zone. This encourages microorganisms to proliferate and promotes healthy soil. All these practices are known to agronomists — there is nothing new or magic about them.
The costs of SRI are low and its potential productivity is very high, which is more important than ever now that the Green Revolution technologies are showing signs of fatigue.
Even when the Andhra Pradesh farmers were unable to implement all aspects of SRI the first season, just planting young seedlings carefully at wider spacing with somewhat better water management resulted in yield increases of more than 2 tonnes per hectare compared with conventional methods using higher inputs.
In 167 on-farm trials, the average yield obtained using SRI practices was 8.1 tonnes per hectare, compared with 5.67 using conventional practices. Average productivity in Andhra Pradesh is 3.89 tonnes per hectare. With more experience, still higher yields may be possible.
Rice yields all over the world have levelled out under the present system of flooded cultivation. We need to be looking for alternatives to existing practices, with an open mind.
SRI is still evolving and I hope that the scientific community will collaborate in refining the technology and working out the scientific reasons for the reported higher productivity. This would be more constructive and more in the spirit of science than dismissing SRI with limited data and preconceptions, when the experiences of farmers are so positive.