Response of rice to rate and time of application of organic materials

Abstract

SUMMARYWheat straw (WS), paddy straw (PS), farmyard manure (FYM) and water hyacinth (Eichhornia crassipes) compost (WHC) were applied at four rates and on four dates before transplanting to the rice cultivar Ratna, in a pot experiment at Kharagpur, India in the wet (first crop) and dry (second crop) seasons of 1985/86. Grain yield of the first crop increased significantly with increasing rates of FYM and WHC up to the equivalent of 15 t/ha but, with the application of WS and PS, the yield was greatest at 10 t/ha and decreased at 15 t/ha. On the other hand, yield increased appreciably when WS and PS were applied up to 30 days before transplanting (DBT) but, with FYM and WHC, such increases were less pronounced. The effect of higher rates (10 and 15 t/ha) was more pronounced with early application of organic materials (20 and 30 DBT). Residual soil fertility estimated by organic carbon and available N, P and K increased under all the organic materials, which favourably influenced growth and yield of the second crop grown without supplementary fertilization. The residual effect of increasing rates of WS and PS in increasing grain yield was significantly higher than with FYM and WHC.