Abstract

It is well known that rice yield in India and South East Asia, countries is very low (Basak, 1956). While low doses of N give conside- rable yield responses (Basak, 1956, Basak et al. 1957 and 1960 and Basak and Klemme, 1959) higher doses of N over 40 16 per acre are seldom effective (Ghose et al. 1956, Mariakulandai, 1957). Crop yields are generally conditioned by soil N content (Jenny, 1941). While tropical soils are low in organic matter and N reserves, failure to secure commensurate yield responses to heavy N application, seems to be a paradox (Basak, 1962). So rice production cannot be boosted merely with larger fertilizer production in these countries in the absence of a solution to this problem (Basak, 1962).

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