Effect of Seed Rate and Incorporation Age of Sesbania rostrata on the Performance of the Following Fice Crop

Abstract

The experiment was conducted on Roi - et series soil at Ubon Ratchathani Rick Research Center in wet seasons of 1987 and 1988. The objectives were to determine the optimum seed rate and time of incorporation of Sesbania rostrata in increasing the yield of rice and to determine the responses of green manure to the phosphate fertilizer. The results showed that the increase in the Sesbania seed rate did not significantly affect the height and the rice grain yield. However, the highest rice grain yield was obtained with the 30 kg./ha seed rate if incorporation of the green manure was delayed to 60 days after seeding. The delay in teh incorporation of the green manure crop from 45 to 60 days after seeding singificantly increased the rice grain yield. The application of 50 kg./ha. of phosphate fertilizer did allow considerably greater Sesbania plant height and fresh weight in both years and significantly increased the rice grain yield at the 45 days of incorporation. Inorganic nitrogen fertilizer application did not increase in the grain yield of rice when compared to the green manure plot. The increase in the rice grain yield (average two yerars) due to green nanure incorporation ranged from 19 tp 80% over the control treatment.