Response of area‐ and yield‐scaled N₂O emissions from croplands to deep fertilization: a meta‐analysis of soil, climate, and management factors

Abstract

BACKGROUND Nitrous oxide (N2O) is an important and persistent greenhouse gas making a significant contribution to global climate change. Deep fertilization has been demonstrated to increase crop yield and nutrient use efficiency by decreasing losses of volatilization and surface runoff. However, N2O emissions from croplands induced by deep fertilization are variable and mitigation strategies remain uncertain. This study aimed to (i) quantify the response of area‐scaled (N2O emissions) and yield‐scaled N2O emissions (N2O intensity) from croplands to deep fertilization, and (ii) identify the soil, climate, and management factors that mitigate N2O emissions and N2O intensity under deep fertilization. RESULTS Compared with the control, deep fertilization increased N2O emissions by 18.6% (P < 0.001) but decreased N2O intensity by 20.1% (P = 0.018). By adopting deep fertilization, N2O emissions could be significantly mitigated in rice‐paddies soils (−48.8%), with fertilizer depth > 10 cm (−33.0%), and with fertilizer N amount > 200 kg N ha−1 (−8.2%). N2O intensity following deep fertilization significantly decreased in soils with pH ≤6 (−22.5%), at sites with precipitation of 500–1000 mm (−25.5%), in rice‐paddies soils (−53.0%), with the method of mixed fertilizer in the control (−21.2%), and with fertilizer depth > 10 cm (−33.6%). CONCLUSION This study provides a basis for assessing the effect of deep fertilization on N2O emissions and provides potential measures to mitigate N2O emissions associated with deep fertilization practices.

Fertilizer placement for improved nitrogen use efficiency and mitigation of N2O emissions

“…Previous field studies have shown that deep fertilizer placement, compared to a broadcast application, increased yields, improved NUE, and decreased N runoff . Regarding N2O emissions, however, results are somewhat contradicting: while deep N fertilizer placement effectively lowered N2O emissions in rice paddies and in field experiments in upland regions (e.g., Chen et al 2021, Pandit et al 2022, as well as in combination with conservation tillage methods Nash et al 2012), other studies (e.g. ) found that N2O emissions were higher from deeper N placement compared to shallow N placement.…”

A global meta‐analysis of yield‐scaled N2O emissions and its mitigation efforts for maize, wheat, and rice

“…Ideally, good management strategies should be identified that allow N 2 O emissions to be reduced while largely maintaining or even increasing crop yields, i.e., the relatively lower yield‐scaled N 2 O emissions. In recent decades, many individual field studies and meta‐analyses have been conducted to investigate the effects of land use and its managements on various crop production and GHG emissions or yield‐scaled GHG emissions (e.g., Chen et al., 2021; Guo et al., 2022; Kim et al., 2023; Kim & Giltrap, 2017; Qin et al., 2012; Sainju, 2016; Shang et al., 2021; Yang et al., 2019; Zhang, Tian, et al., 2020). The findings of these studies highlight that yield‐scaled GHG emissions are an excellent indicator for assessing the environmental efficiency of a cropping system.…”

Lysimeter deep N fertilizer placement reduced leaching and improved N use efficiency

“…In the literature, what qualifies as a deep placement depth can differ widely, depending on the existing local practice for fertilization for the particular cropping system. Although placement depth, as well as climate and growing systems vary, deep N placement relative to surface fertilization has been reported to increase yields and NUE, decrease ammonification, and in some cases decrease N 2 O emissions (Chen et al 2021;Pandit et al 2022;Rychel et al 2020;Sosulski et al 2020;Wu et al 2021;Zhang et al 2022;). However, NO 3 − remaining in the soil after crop uptake is susceptible to leaching and literature on the fate of NO 3 − following deep fertilization is scant.…”