SRI update

The July/September 2001 issue of Appropriate Technology (Volume 28, No. 3) included several articles about SRI (System of Rice Intensification; see EDN 70).

One article stated that scientists at the International Rice Research Institute (IRRI) have examined the components of SRI. Many of the components are already used, they say, in parts of Asia. IRRI scientists concur that “SRI can substantially boost rice yields in certain areas.” However, they have not actively promoted it in Asia for a number of reasons: it is very labor intensive; it requires careful water management; many of the components have already been adopted by rice farmers in Asian countries; and even in Madagascar (where the technology was developed), the technology has not been widely adopted by farmers.

However, work to demonstrate the benefits of SRI has continued. In another article in the same issue, Dr. Norman Uphoff described an experiment done in Madagascar by Jean de Dieu Rajaonarison and his advisor, Professor Robert Randiamiharisoa, in the Faculty of Agriculture (ESSA) at the University of Antananarivo. Two rice varieties—a high-yield variety and a traditional local variety—were compared. Both showed the same patterns of response.

Uphoff wrote, “The SRI practices compared against conventional methods were: age of transplanting (8 days v 16 days); number of plants per hill (1 v 3); water management (aerated soil v flooded soil); and fertilization – compost v NPK (16-22-11) v no fertilization.

“The high-yielding variety produced 2.4 times more rice with SRI practices compared to conventional methods. The local variety yielded 2.8 times more. These results can be analyzed several ways to ascertain how much contribution each practice made to yield differences, other things being equal, under these particular soil, climatic and other conditions.

“For these particular varieties and for these particular growing conditions, planting young seedlings contributed most to yield: an extra 1.35 t/ha. Careful water management, using a minimum of water and keeping soil well drained and aerated, was next most important, adding 0.85 t/ha. Planting single seedlings added 0.46 t/ha. Using compost increased yield by 0.27 t/ha over what was obtained, on average, using NPK fertilizer.

“That adds up to a total of just under 3 t/ha increase in yield, but when the four practices were used altogether yields increased by 4 t/ha. This shows…an interaction effect or synergy of over 1 t/ha. It is, therefore, in the farmer’s interest to use all the SRI practices, instead of picking and choosing.”