[Effects of biochar application patterns on soil nutrients and nitrogen- and phosphorus-related enzyme activities in Phaeozem and Luvisol].

We investigated the effects of different biochar application patterns on soil nutrient contents and element transformation, with soil samples being collected from two five-year field experiments in Phaeozem and Luvisol amended with biochar at annual low-rate (AL, 22.5 t·hm-2·a-1) and intervalic high-rate (IH, 112.5 t·hm-2·5 a-1). Changes of soil total carbon (C), nitrogen (N) and phosphorus (P) contents as well as the related enzyme activities were measured under different biochar application patterns to provide fundamental information for the straw utilization and soil fertility improvement in agroecosystem. Results showed that total C and organic N contents in AL treatment were significantly higher than those in IH treatment in Phaeozem soil. Compared with the control, the decreases of dehydrogenase activity in AL treatment was more pronounced than that in IH treatment in Phaeozem soil, and the increases of protease activity in IH treatment was pronounced than that in AL treatment in Luvisol. Compared with Luvisol soil, the application of biochar had stronger effect on total soil C and organic N contents in Phaeozem soil. Application of biochar significantly increased the activities of soil dehydrogenase and protease in Luvisol soil, but decreased the activity of soil dehydrogenase. Soil types and biochar application patterns interacted to affect soil C and N contents, microbial metabolic activity, N- and P-related enzyme activities. In summary, soil types and biochar addition affected soil properties and microbial characteristics, which would provide important information for straw application and soil management.