Is SRI in Conflict with ‘Conventional Wisdom’? P. Kishan Rao
There have been claims and counter claims about the scientific basis of SRI and its performance on both research farms and farmers’ rice fields. This paper asks some probing questions on the idea, concept and practices of SRI vis-à-vis conventional rice cultivation as understood and experienced by the scientists and farmers at different times.
Land • Any and every land is suitable for SRI provided it fulfills two conditions: • The land in question should be part of a stabilized rice eco-system. • The land area should be limited to the proportionate availability of compost.
Dichpali Experiment (1933) No. 1 Plot No. 2 Plot No. 3 Plot • Amount of land measured for the contrast. All portions had the same cultivation 6,394 sq. ft. 6,394 sq. ft. 6,394 sq. ft. • Amount of seed sown. All the seed sown was the same quality 6 lb. 6 lb. 6 lb. • Amount of rice taken in each case by measure, not weight 422 lb. 236 lb. 60 lb. • Amount of straw in similar sized bundles 138 bundles 106 bundles 40 bundles • Note that No.1 Plot had 1.25 to 1.5 inches compost; No.2 Plot had some farm rubbish plus 3/8 inch of Indore compost; and No.3 Plot was the control and had no nutrient amendments (2.2 lb=1 kg) Source: Howard, An Agricultural Testament, 1938
Tilling … • The store of nitrogen in the soil in the form of organic matter has to be carefully conserved: it is part of the cultivator's working capital. • Too much cultivation and deep ploughing will oxidize this reserve and the balance of soil fertility will soon be destroyed. (Howard, 1938, p. 8)
Water • If the field is located in an area with assured water supply throughout the crop period, then the farmer/s should be capable of controlling the supply of water and its drainage at all times
Timing • For any particular agro-climatic zone, there is always a short time band that is ideal time for cultivating rice • Experience has shown that a much delayed transplanting of SRI has yielded more than the conventional paddy with all other conditions being the same
Seed1) Direct Seeding • “My rice, on the other hand, was grown in accordance with the natural life cycle of the rice plant, just as though it were growing wild. I wait patiently for the plant to develop and mature at its own pace.” (Fukuoka, 1978, p. 56)
Seed2) Seedbed Method • Wherever possible, seedbed can be prepared with sand and compost as this method has distinct advantages over soil and compost combination for handling the young seedlings
Land Preparation • Wherever possible, puddling and deep ploughing should be avoided, and the tilling depth should be limited to around 4” (10 cm)
Transplantation : SRI • The ideal time for transplantation is when the seedling has two leaves • From IRRI Media Summary: “Transplanting rice seedlings as early as possible can significantly increase grain yield in irrigated areas”(Estela Pasuquin et al., in Crop Science: http://www.cropscience.org.au/icsc2004)
Fertilisers/Manures • During the ‘green revolution’ era, the introduction of chemical fertilizers in combination with high-yielding dwarf varieties with more and more areas having assured irrigation added year after year increased productivity and production substantially. Presently those yields are no more maintainable even with addition of large quantity of fertilizers
Irrigation • “Rice plants grow best when the water content in the soil is between 60 to 80 percent of its water-holding capacity. When the field is not flooded plants develop stronger roots and are extremely resistant to attacks by disease and insects.” (Fukuoka, 1978, p. 54)
Diseases • “As the overwhelming majority of chemical pesticides are nitrogenous and often chlorinated these, in turn, create a situation that is unfavourable for the plant’s resistance…” (F. Chaboussou, 2004, p. 208)
Weedicides • Unlike in conventional rice cultivation, in SRI, weeds are considered as a challenge and more of an opportunity of providing the much-needed organic matter in the form of green mulch which is essential for building strength and disease resistance as well. Application of weedicides negates these benefits and, on the other hand, makes the rice plant vulnerable
Tillering/Root Intensification • A single plant (whether transplanted or directly sown) is eminently capable of producing more tillers and root volume under near-saturated conditions, and consequently more grains per unit area of soil. • Understandable in terms of the Katayama Tillering Principle
Mechanical/Hand Weeding • The idea behind weeding in conventional rice cultivation is to provide the rice plants unhindered access to all the nutrients, both natural and artificially provided, by clearing the weeds from time to time. • SRI takes up this idea in earnest and leads to its logical conclusion by converting a menace into an opportunity for providing crop nutrition. The weeding activity also results in aeration to the roots that is otherwise improbable in submerged conditions
The Pragmatic Approach • The scientific community and the farming community the world over may well come together in solving the problems of water shortages, soil degeneration and growing hunger and, in a spirit of cooperation and brotherhood, they should work for the common good of all living beings
Conclusion • The cultivation of rice has recently been going through a complete metamorphosis in so far as the principles underlying its practices and, eventual, grain yields. • SRI is one such activity that has forced scientists and farmers alike to have a re-look at the whole gamut of issues ranging from food production and resource conservation to also ecological, ethical and environmental considerations
SRI is, as a catalyst, bringing about a change for better and helping validate what is ‘Conventional Wisdom’.
Thank You Kishan Rao Parcha