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(DN),Olsen-P,and microbial biomass C,N,P(BC,BN,BP) of 254 paddy soils(018 cm) in hilly red soil region of subtropical zone of China were studied.The results showed that the contents of SOC,TN,BC,BN 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,BP and available P(the sum of BP and OlsenP) contents were not significant between various positions.In addition,the ratios of soil C/N,BC/BP and BC/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,BC/BN,BN/TN and BP/TP were not significant statistically between various positions.