Atmospheric Nitrogen (N) deposition profoundly influence litter decomposition and thus ecosystem biogeochemical cycles. N deposition not only encompasses IN, but also ON (e.g. urea and amino acids), which may contribute to 30% of total atmospheric N deposition. Litter decomposition is a key biogeochemical process that influences the recycling of nutrient, carbon (C) and energy in ecosystems. How this fundamental process is affected by different forms of nitrogen (N) deposition is still uncertain. 

DONG Lili and his colleagues from the Institute of Applied Ecology of the Chinese Academy of Sciences (CAS) conducted a two-year field experiment to investigate the effects of different forms of N addition on root decomposition among five dominant grass species in a temperate grassland in Northern China. 

According to the researchers, all exogenous N additions, both IN and ON forms, stimulated the decomposition rates across species. Moreover, the mixture of IN and ON addition treatment increased decomposition rate most by 20% higher than control and 12% higher than using just IN addition across the five studied species.  

The results highlight the need for studies of N effects on litter decomposition that consider the ON components in simulating N deposition experiments. Ignoring the organic N source may underestimate the potential effects of natural N deposition on ecosystem. 

This study entitled "Response of fine root decomposition to different forms of N deposition in a temperate grassland" has been published in Soil Biology and Biochemistry. 

This study was funded by the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the China Postdoctoral Science Foundation.