Effects of Nitrogen Fertilization on Litter and Soil Decomposition: Cumulative Microbial Respiration

The influence of inorganic nitrogen (N) inputs on decomposition is poorly understood. Some prior studies suggest that N may reduce the decomposition of substrates with high concentrations of lignin via inhibitory effects on the activity of lignin-degrading enzymes, although such inhibition has not always been demonstrated. The purpose of E145 was to study the effects of nitrogen (N) addition on decomposition of seven substrates ranging in initial lignin concentrations (from 7.4 - 25.6%) over five years in eight different grassland and forest sites in central Minnesota.

目前学界对无机氮（inorganic nitrogen, N）输入调控有机质分解的机制尚不明晰。既往多项研究表明，氮素可通过抑制木质素降解酶的活性，降低高木质素浓度底物的分解速率，但此类抑制效应并非总能被观测证实。本实验E145旨在探究氮添加对7种初始木质素浓度介于7.4%~25.6%的底物分解过程的影响，实验周期为5年，覆盖美国明尼苏达州中部的8处不同草原与森林样地。