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New Delhi: Prime Minister Narendra Modi recently challenged agricultural scientists and farmers to produce “per drop more crop"—a call to promote water conservation. The demand is valid because India’s land resources are limited and demand for food keeps growing, says Norman Uphoff, professor of government and international agriculture at Cornell University in the US.

Meeting this challenge is made more difficult, and more urgent, by the disruptive effects of climate change, which is making water supplies less sufficient and less reliable. Fortunately, says Uphoff, farmers in many states of India over the past decade have already begun producing more crop per drop of water and more crop per acre of land by adopting to a new process of rice cultivation known as system of rice intensification (SRI).

In an email interview, the global campaigner of SRI speaks on the Indian experience and how it can help in drought mitigation.

How does the SRI system of crop management work?

SRI modified the way that rice plants, soil, water and nutrients are managed—transplanting younger seedlings in the field in widely spaced rows, no continuous flooding of paddy fields, active soil aeration with a mechanical weeder, and as much addition of organic matter as is available. These practices enable the plants to grow much larger, stronger, healthier root systems, and they stimulate the growth of soil organisms, to be more abundant, diverse and active. Better root systems and more life in the soil are the basic drivers for SRI results, and these are things that were almost completely neglected by the Green Revolution technology.

How has India’s experience been?

SRI was introduced into India about 15 years ago. From data supplied by Indian colleagues in different states, I have calculated that average SRI yields across varying conditions in the country are about 5.6 tonnes per hectare compared with 3.7 tonnes per hectare produced with standard methods. This value of this increment, 1.9 tonnes per hectare, would amount, at common purchase prices, to about 3,230 crore for 2013, and it is rising every year. This estimate does not take account of the lower costs of SRI production, nor the value of the reduced water requirements, nor the improvements being made in soil quality and soil health.

Can SRI help in drought conditions?

The SRI methods of crop management have two main effects: to promote the growth of larger, deeper, long-lived root systems, and to support the growth of more and more diverse soil organisms, from microbes to earthworms. When the soil dries out, it loses moisture from the top, so even when the surface is desiccated, there is moisture in lower horizons of the soil.

Also, when there is abundant life in the soil, this maintains reserves of water in the soil, whereas non-living, dead soil becomes totally dried out. Also, these creatures improve the structure of the soil so that it remains more absorbent of whatever water there is. These effects of SRI practices on the structure and functioning of soil systems makes them better able to support plant life, which can then tolerate the stresses of drought. There are limits to such protection, of course, but these effects are very beneficial.

Your take on controversies regarding high reported yields.

SRI is perhaps best known in India for the controversy over certain “super-yields" that have been reported with its methods, welcomed in some circles and rejected in others. In 2011 kharif season, a farmer in Nalanda district of Bihar, Sumant Kumar, had a yield of 22.4 tonnes per hectare, measured with standard methods by Bihar Agriculture Department personnel, with hundreds of observers watching. Subsequently, in 2013-14 in Tamil Nadu, a farmer in a village near Madurai achieved a yield of 23.4 tonnes per hectare with SRI methods. This report drew hardly any notice.

Such high yields are outliers, but they show the productivity that exists within our current rice varieties when the best conditions for plants’ growth and health are provided, enabling them to express their full potential. Such super-yields are not as important as the large differences in average yield that are seen between SRI and conventional management, using less water. It is averages rather than outliers that feed the majority of people and make farmers more prosperous. But we should be trying to understand how and why outlying results are achieved, so we can move the average in their direction.

Can this crop management system be expanded to crops other than rice?

In recent years, Indian farmers have also begun adapting and extrapolating SRI’s ideas and methods to other crops beyond rice. There is an expanded version of SRI called the System of Root Intensification in Bihar, and a more encompassing System of Crop Intensification (SCI) that improves the productivity and resilience of crops like wheat, ragi, sugarcane, maize, mustard, all the grams, and even some vegetables.

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