Spatial variation in organic carbon,nutrients and microbial biomass contents of paddy soils in hilly red soil region

The contents of soil organic C(SOC),total N(TN),total P(TP),dissoluble N(D_N),Olsen-P,and microbial biomass C,N,P(B_C,B_N,B_P) of 254 paddy soils(0—18 cm) in hilly red soil region of subtropical zone of China were studied.The results showed that the contents of SOC,TN,B_C,B_N and DON of paddy soils at bottom of hills were 14.6%,13.6%,24.6%,20.4% and 95.8% higher than that of paddy soils at foothill,respectively.The Olsen-P contents of paddy soils at foothill were 33.3% higher than that at bottom of hills.However,the differences in TP,B_P and available P(the sum of B_P and OlsenP) contents were not significant between various positions.In addition,the ratios of soil C/N,B_C/B_P and B_C/SOC of paddy soils at bottom of hills were 12.7%,28.5% and 8.2% higher than that at foothill,respectively,but the differences in ratios of soil C/N,B_C/B_N,B_N/TN and B_P/TP were not significant statistically between various positions.