Responses of Soil Nitrogen Pools to Litter Input Under Nitrogen Addition: A Meta‐Analysis

Abstract

AbstractLitter input essentially regulates soil nitrogen (N) and phosphorus (P) pools in natural ecosystems, but uncertainties remain about how this regulation is affected by increasing N deposition. Here, we synthesized 1,263 observations from 34 field studies with paired treatments to elucidate how N addition affects the responses of soil N and P pools to litter input. Our results showed that the combination of litter input and N addition significantly enhanced soil N pools, with increases in total N (13.7%), microbial biomass N (38.7%), ammonium N (37.7%), and nitrate N (79.0%), but slightly affected soil P pools. Strikingly, soil N pools in forests displayed more positive responses to combined treatment than those in grasslands. Furthermore, experimental design and mean annual precipitation were critical controllers in regulating the responses of soil N pools to combined litter input and N addition. The present results underscore the importance of combined litter input and N addition in promoting soil N pools, thereby providing essential insights into how N addition can change nutrient cycling within natural ecosystems.