Fertilizer response functions of rice in Sri Lanka: estimation and some applications
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Kikuchi, M.; Aluwihare, P. B. 1990. Fertilizer response functions of rice in Sri Lanka: estimation and some applications. Colombo, Sri Lanka: International Irrigation Management Institute (IIMI). 15p. + annex.
Permanent link to this item: http://hdl.handle.net/10568/39513
Internet URL: http://publications.iwmi.org/pdf/H_6935.pdf
Rice fertilizer response functions, at the farm level as well as at the experiment station level, were estimated by type of variety and by type of irrigation condition, and applied to i) explain the long-term growth path of rice production in Sri Lanka after the independence; ii) identify the degree of contribution of the rice varietal improvements to the increase in rice production; iii) check the consistency of the past and current fertilizer recommendations for rice; and iv) examine the possible impacts of fertilizer subsidy withdrawal on rice production in the country. The estimated response functions at the farm level reproduce well the macro growth path of rice production except for the 1970s when new improved varieties performed less satisfactory due to their susceptibility to insect, pest and drought. More than forty percent of the increase in rice production in the last four decades is attributable to the varietal improvements. The past and present fertilizer recommendations for rice are consistent with the response functions estimated. The long-run impacts of withdrawal of fertilizer subsidy in the rice sector would not be large as far as its yield impacts are concerned.