Nitrogen and Phosphorus Related Hydrolytic Enzyme Activities Influenced by N Deposition under Semi-Arid Grassland Soil

Abstract

Eight enzyme activities involved in N and P cycling and soil basic properties influenced by four years of nitrogen (N) deposition were investigated under a semi-arid grassland soil, Northern China. Results showed that N addition into soil could cause soil acidification significantly. Inorganic dissolved N (NH 4 + N and NO 3 N) concentration increased significantly while Olsen-P concentration changed slowly with simulating N deposition. Soil nitrification potential, protease, nitrate reductase, and phosphodiesterase activities were repressed by higher rate of N deposition caused by higher NH 4 + concentration or soil acidification. Soil alkaline phosphomonoesterase activities correlated positively with soil pyrophosphatase activities due to the microbial origin of alkaline phosphatase and pyrophosphate. Positive correlation of acid phosphomonoesterase activities and soil TC was also observed in the study.