Department of International Agricultural Development, Tokyo University of Agriculture, Setagaya, Tokyo, Japan.
Oecologia. 2011 Aug;166(4):863-7. doi: 10.1007/s00442-011-1942-z. Epub 2011 Feb 26.
Nitrogen use efficiency (NUE) was originally defined as the dry mass productivity per unit N taken up from soil. The term was subsequently redefined as the product of nitrogen productivity (NP) and mean residence time of nitrogen (MRT). However, this redefinition was found to contradict the original definition under certain conditions, and confusion arose when the MRT defined for a steady-state system was applied to a system that was actually not at steady state. As MRT is the expected length of time that a unit of N newly taken up from soil is retained before being lost, it can be translated into the plant nitrogen duration (PND) divided by the total N uptake. This MRT is determined equally well for a steady state- and a non-steady state system and is in accordance with the original definition of NUE. It can be applied to a herbaceous perennial stand (that was at a steady state) and to an annual stand (that was not at a steady state) to determine NUE. NUE is also applicable when plant growth and reproduction are analyzed in relation to N use.
氮素利用效率（NUE）最初被定义为单位氮从土壤中吸收的干物质生产力。后来，该术语被重新定义为氮生产力（NP）和氮平均停留时间（MRT）的乘积。然而，在某些条件下，这种重新定义与原始定义相矛盾，并且当将为稳态系统定义的 MRT 应用于实际上不在稳态的系统时，会产生混淆。由于 MRT 是从土壤中新吸收的单位氮在丢失之前被保留的预期时间长度，因此可以将其转换为植物氮持续时间（PND）除以总氮吸收量。对于稳态和非稳态系统，MRT 的确定同样良好，并且与 NUE 的原始定义一致。它可用于草本多年生林分（处于稳态）和一年生林分（非稳态）来确定 NUE。当分析植物生长和繁殖与氮利用的关系时，NUE 也适用。
