Abstract
The effects of farmyard manure application and water management on the growth and grain yield of rice and CH4 and N2O emission from the paddy field were examined from 2001 to 2003. By application of farmyard manure at a rate of 200kg/a, rice growth and grain yield were reduced as compared with that with chemical fertilizer application, but the emission rate of CH4 was little affected. Application of farmyard manure at a rate of 500–1000 kg/a increased rice growth and grain yield, but it also increased the emission rate of CH4. In the plot with intermitted irrigation, application of farmyard manure increased the Eh value, and thus did not increase CH4 emission, although it slightly reduced grain yield. In 2003 with on extremely low temperature and limited sunshine hours, application of heavy farmyard manure increased rice growth, but not grain yield due to panicle blast. The intermitted irrigation was reported to induce N2O emission, but it caused little on N2O emission in the present study. Thus the grain yield in the field with heavy application of farmyard manure was as high as that in the yield with heavy application of chemical fertilizer. CH4 emission was increased by heavy farmyard manure, but it was lowered by restriction of irrigation.
