[Soil C, P and microbial biomass C, P response to different fertilizations in the hillslope cropland of purple soil].

The aim of this study is to explore the changes and coupling characteristics of carbon( C),phosphorus( P) and microbial C,P in a hillslope cropland of purple soil. The results showed that total organic carbon( TOC) ranged from 90. 8 to 100. 8 g·kg-1under organic fertilizer or straw combined with inorganic fertilizer treatments( including N,NP and NPK) as compared with nitrogen( N) application only( 62. 2 g·kg-1). Total phosphorus( TP) ranged from 0. 65 to0. 84 g·kg-1in organic combined with inorganic fertilization treatments,and that under straw combined with inorganic fertilizer treatments was 23%-38% of organic fertilizer combined with inorganic fertilization treatments. The microbial biomass phosphorus( MBP) under N fertilizer was significantly decreased as compared with combined fertilization treatments. The ratios of microbial biomass carbon( MBC) to MBP under combined fertilization treatments were between 5 to 26,and the TOC / TP ratios under organic fertilizer and straw combined treatments were between 92 to 137 and 296 to 653, respectively,while those under N fertilizer treatment were 59 and 2000,respectively. The results indicated that combined organic and inorganic fertilizers would be helpful for enhancing P availability and increasing its potential capacity in purple soil.