Effects of nitrogen deposition rates and frequencies on the abundance of soil nitrogen-related functional genes in temperate grassland of northern China

Abstract

Purpose: Microbial processes driving nitrogen (N) cycling are hot topics in terms of increasing N deposition. Abundances of N-related functional genes (NFG) can be most responsive to N deposition and commonly used to represent N transformation rates. However, empirically simulated N deposition has been exclusively conducted through large and infrequent N fertilization, which may have caused contrasting effects on NFGs. Therefore, experiments with small and frequent N additions closed to natural deposition are necessary. Materials and methods: Independently manipulated N addition rates (i.e., 0, 5, 10, 15, 20, and 50 g N m−2 year−1) and two frequencies (2 times per year addition as convention..