Comparisons of Yield, Water Use Efficiency, and Soil Microbial Biomass as Affected by the System of Rice Intensification

To compare the effects of the system of rice intensification (SRI) on yield, water use efficiency, and microbial biomass in associated rice soils, a field experiment was conducted in 2004 at the Agriculture Experimental Farm of Zhejiang University in Zhejiang Province, China. The treatments evaluated were traditional flooding (TF) vs. SRI cultivation methods. Grain yield in the SRI treatment was 26.4% greater than that in the TF treatment, reducing water use by 461.5mm. Compared to TF, SRI increased water use efficiency by 91.3% and irrigation water use efficiency by 194.9%. Soil microbial indicators during the rice-growing season also diverged between TF and SRI. Microbial biomass C (MBC) was in the range of 101-196mgkg-1 for TF vs. 113-224mgkg-1 for SRI; microbial biomass N (MBN) was in the range of 14-33mgkg-1 for TF vs. 28-53mgkg-1 in SRI. Compared to TF, SRI significantly increased both MBC and MBN, regardless of sampling date.