Global ammonia emissions from synthetic nitrogen fertilizer applications in agricultural systems: Empirical and process‐based estimates and uncertainty

Abstract

Excessive ammonia (NH3) emitted from nitrogen (N) fertilizer applications in global croplands plays an important role in atmospheric aerosol production, resulting in visibility reduction and regional haze. However, large uncertainty exists in the estimates of NH3 emissions from global and regional croplands, which utilize different data and methods. In this study, we have coupled a process‐based Dynamic Land Ecosystem Model (DLEM) with the bidirectional NH3 exchange module in the Community Multiscale Air‐Quality (CMAQ) model (DLEM‐Bi‐NH3) to quantify NH3 emissions at the global and regional scale, and crop‐specific NH3 emissions globally at a spatial resolution of 0.5° × 0.5° during 1961–2010. Results indicate that global NH3 emissions from N fertilizer use have increased from 1.9 ± 0.03 to 16.7 ± 0.5 Tg N/year between 1961 and 2010. The annual increase of NH3 emissions shows large spatial variations across the global land surface. Southern Asia, including China and India, has accounted for more than 50% of total global NH3 emissions since the 1980s, followed by North America and Europe. Rice cultivation has been the largest contributor to total global NH3 emissions since the 1990s, followed by corn and wheat. In addition, results show that empirical methods without considering environmental factors (constant emission factor in the IPCC Tier 1 guideline) could underestimate NH3 emissions in context of climate change, with the highest difference (i.e., 6.9 Tg N/year) occurring in 2010. This study provides a robust estimate on global and regional NH3 emissions over the past 50 years, which offers a reference for assessing air quality consequences of future nitrogen enrichment as well as nitrogen use efficiency improvement.

The Influence of Alkalization and Temperature on Ammonia Recovery from Cow Manure and the Chemical Properties of the Effluents

“…The volatilization, seepage, and leaching of various compounds from manure result in air and water pollution, especially during the handling and storage of manure [4]. The main sources of ammonia emissions from the animal feeding industry, as described by the US-EPA, are cattle (54%), poultry (33%), and hogs or pigs (12%) [5]. Nearly half of the emissions are from manure operations, which include manure applied to pasture (15%), manure management (7%), and manure applied to soil (3%) [3].…”

Effect of urease and nitrification inhibitors on ammonia volatilization and abundance of N‐cycling genes in an agricultural soil

“…Urease is the enzyme responsible for the conversion of urea into carbon dioxide (CO 2 ) and NH 3 . When applied to the soil, approximately 17% of urea-N is directly lost as NH 3 volatilized into the atmosphere (Pan et al, 2016;Cantarella et al, 2018;Xu et al, 2019). However, this loss can be reduced by applying urease inhibitors, which slow down urea hydrolysis, thus decreasing the peak concentration of ammonium in the soil solution and reducing the concomitant soil pH increase (Francisco et al, 2011;Abalos et al, 2012;Modolo et al, 2015).…”

An improved mechanistic model for ammonia volatilization in Earth system models: Flow of Agricultural Nitrogen, version 2 (FANv2)

“…The process model FAN (Flow of Agricultural Nitrogen) described by Riddick et al (2016) was developed in part to assess the climate sensitivity of ammonia volatilization. In contrast to specialized models developed to evaluate ammonia emissions arising in application of manure slurry (Genermont and Cellier, 1997;Hamaoui-Laguel et al, 2011), synthetic fertilizers (Rachhpal-Singh and Nye, 1986;Bash et al, 2013;Xu et al, 2019), or from urine patches on pastures (Sherlock and Goh, 1985;Móring et al, 2016;Giltrap et al, 2017), FAN aims to evaluate NH 3 emissions globally and throughout the agricultural sector.…”