Short-term Effect of Nitrogen Addition on Litter and Soil Properties in Calamagrostis angustifolia Freshwater Marshes of Northeast China

Nitrogen (N) addition can affect soil organic matter (SOM) decomposition by enhancing soil enzyme activity, increasing labile organic carbon (C) fractions and decreasing litter C/N ratio. This study was designed to investigate the short-term effect of N addition on litter and soil chemical and biological properties in Calamagrostis angustifolia freshwater marshes. A field experiment was conducted in which soil was treated with N addition of 0 (N0), 12 (N1), and 24 (N2) g N m −2 year −1 , respectively. Above-ground biomass increased by 40 % and 32 % for N1 and N2 treatment, respectively. Added N increased litter C and N concentrations as well as β-glucosidase and invertase activities. However, litter C/N ratio decreased with N addition. N1 treatment increased microbial biomass carbon (MBC) in both topsoil and subsoil, but no changes in dissolved organic carbon (DOC) were observed. Total N concentrations in subsoil increased both in N1 and N2 treatments; NH 4 + -N decreased in the N1 treatment, while NO 3 − -N increased in the N2 treatment in topsoil. N2 treatment increased β-glucosidase, invertase, and urease activities in both soil layers. The differences in litter and soil characteristics caused by N addition suggest that N addition has the capacity to increase soil C transformation rates in marshland.