SEASONAL VARIATION OF MICROBIAL BIOMASS C AND SOIL RESPIRATION IN RICE PADDIES IN BLACK EARTH AND CORRELATION BETWEEN THEM AND CH4 EMISSION

Microbial biomass C, soil respiration and CH4 emissions were measured during the whole rice growth period in rice paddies in black earth. The results showed microbial biomass C and soil respiration were depressed significantly by application of slow-releasing urea at the early stage of rice growth period (P<0.05), but were almost not affected by intermittent irrigation. CH4 emission, on the average, was reduced by 32.5 % in the intermittent irrigation treatments, compared to the control. But CH4 emission was, in the general, not significantly affected by application of slow-releasing urea. CH4 emission was significantly related to microbial biomass C in slow-releasing urea treatments. Key words black earth CH4 emission microbial biomass soil respiration CH4 is one of the most important greenhouse gases. Although th