Piling up reactive nitrogen and declining nitrogen use efficiency in Pakistan: a challenge not challenged (1961–2013)

Abstract

Excessive nitrogen (N) application and reduced nitrogen use efficiency (NUE) are the key reasons behind N notoriety worldwide, including in Pakistan. We estimated the changes in NUE of Pakistan by calculating the N budget of Pakistan’s agriculture during the last 53 years (1961–2013). A more than ten-fold increase in N input (including N fertilizer, biological N fixation, manure, and atmospheric deposition) from 408 GgNyr ^−1 (1961–1965) to 4636 GgNyr ^−1 (2009–2013) highlights the fact that Pakistan is experiencing a massive expansion of N consumption. Significantly declining NUE (from 58% to 23%) and sharply increasing surplus N (171 GgNyr ^−1 to 3581 GgNyr ^−1 ) may cause N-related environment problems in the future if not handled immediately. Escalating gaseous N emissions of NH _3 , N _2 O, and NO (70, 10, and 1 GgNyr ^−1 to 1023, 155, and 46 GgNyr ^−1 , respectively) is already posing a serious threat in terms of impaired air quality. There is a dire need to devise/adapt strategies and consistent policies for improving NUE, using proper management approaches at the grass root level and applying appropriate legislative measures for judicious N use as per crops requirements. Moreover, promotion of a balanced use of fertilizers would help in improving NUE in agriculture.

Keywords

• reactive N
• nitrogen use efficiency
• gaseous N emissions
• N trade