Nitrogen Use Efficiency by Annual and Perennial Crops

Abstract

The amount of nitrogen fertilizer applied to plants is usually large. Only part of this fertilizer, of about 6--50{\%}, is taken up by plants, depending on fertilizer, plant and soil type, climatic conditions, and agricultural practices. The unaccounted nitrogen can be emitted from the ecosystem as trace gas and ammonia volatilization, or lost by leaching and runoff in the nitrate or ammonium form. The goal of reducing mineral nitrogen usage will be to this twenty-first century what the goal of reducing pesticides was to the last century. In the present study we reviewed the different concepts for nitrogen use efficiency by annual and woody plants. The major points were (i) understanding the terminology and the context in which each concept for nitrogen use efficiency has been used for annual and perennial woody plants, (ii) identifying the critical steps of controlling plant nitrogen use efficiency, and (iii) addressing new approaches to improve the efficiency for annual and perennial woody plants.