{"title":"Is partial substitution of animal manure for synthetic fertilizer a viable N2O mitigation option? An integrative global meta-analysis","authors":"","doi":"10.1016/j.fcr.2024.109574","DOIUrl":null,"url":null,"abstract":"<div><h3>Context or problem</h3><p>Partially substituting synthetic fertilizer by animal manure has been proposed as a sustainable agricultural practice, from the perspectives of improving soil quality and mitigating climate warming.</p></div><div><h3>Objective or research question</h3><p>Previous studies showed that manure application combined with synthetic fertilizer (MACSF) also altered soil nitrous oxide (N<sub>2</sub>O) emissions, while the magnitude varied substantially among experiments. We hypothesized that the difference in local conditions may be responsible for the contrasting impact of MACSF on N<sub>2</sub>O emissions, while their significance and relative importance have not been explicitly assessed.</p></div><div><h3>Methods</h3><p>In order to quantify the response of N<sub>2</sub>O emissions to MACSF and its geographic variability, we conducted a meta-analysis by combining 291 observations from 103 sites across the globe. Also, we evaluated the impact of local conditions on N<sub>2</sub>O emissions and compared their relative importance using the gradient boosting decision tree (GBDT) algorithm.</p></div><div><h3>Results</h3><p>Overall, MACSF did not have significant effect on soil N<sub>2</sub>O emissions, with a global average effect size (ES) of 1.07 ± 0.10 (95 % confidence interval, CI) relative to the same amount of synthetic nitrogen fertilizer. The corresponding N<sub>2</sub>O emission factor (EF) was estimated as 0.93 ± 0.13 % (95 % CI). However, both ES and EF varied substantially with local conditions, of which the substitution ratio (SR) and soil pH were identified as the most important factors. The ES increased significantly (<em>p</em> < 0.01) with the increasing SR. Critical SR was approx. 50 %, above which MACSF may exacerbate N<sub>2</sub>O emissions. Moreover, both response indices increased significantly with the decreasing soil pH. MACSF in acidic soils (pH < 6.5) tended to increase N<sub>2</sub>O emissions, with ES significantly (<em>p</em> < 0.05) higher than 1.0.</p></div><div><h3>Conclusion</h3><p>The contribution of MACSF to N<sub>2</sub>O mitigation varies subustantially with local conditions, of which SR and soil pH are the most important two. MACSF reduces N<sub>2</sub>O emissions only in the cases with low SR and neutral to alkaline soils.</p></div><div><h3>Implications or significance</h3><p>This study offers an integrative global synthesis of the impact of MACSF on N<sub>2</sub>O emissions. By identifying the key controlling factors, the findings serve to guide the development of region-specific tailored substitution strategies, considering its contribution to N<sub>2</sub>O emission mitigation.</p></div>","PeriodicalId":12143,"journal":{"name":"Field Crops Research","volume":null,"pages":null},"PeriodicalIF":5.6000,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Field Crops Research","FirstCategoryId":"97","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0378429024003277","RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"AGRONOMY","Score":null,"Total":0}
引用次数: 0
Abstract
Context or problem
Partially substituting synthetic fertilizer by animal manure has been proposed as a sustainable agricultural practice, from the perspectives of improving soil quality and mitigating climate warming.
Objective or research question
Previous studies showed that manure application combined with synthetic fertilizer (MACSF) also altered soil nitrous oxide (N2O) emissions, while the magnitude varied substantially among experiments. We hypothesized that the difference in local conditions may be responsible for the contrasting impact of MACSF on N2O emissions, while their significance and relative importance have not been explicitly assessed.
Methods
In order to quantify the response of N2O emissions to MACSF and its geographic variability, we conducted a meta-analysis by combining 291 observations from 103 sites across the globe. Also, we evaluated the impact of local conditions on N2O emissions and compared their relative importance using the gradient boosting decision tree (GBDT) algorithm.
Results
Overall, MACSF did not have significant effect on soil N2O emissions, with a global average effect size (ES) of 1.07 ± 0.10 (95 % confidence interval, CI) relative to the same amount of synthetic nitrogen fertilizer. The corresponding N2O emission factor (EF) was estimated as 0.93 ± 0.13 % (95 % CI). However, both ES and EF varied substantially with local conditions, of which the substitution ratio (SR) and soil pH were identified as the most important factors. The ES increased significantly (p < 0.01) with the increasing SR. Critical SR was approx. 50 %, above which MACSF may exacerbate N2O emissions. Moreover, both response indices increased significantly with the decreasing soil pH. MACSF in acidic soils (pH < 6.5) tended to increase N2O emissions, with ES significantly (p < 0.05) higher than 1.0.
Conclusion
The contribution of MACSF to N2O mitigation varies subustantially with local conditions, of which SR and soil pH are the most important two. MACSF reduces N2O emissions only in the cases with low SR and neutral to alkaline soils.
Implications or significance
This study offers an integrative global synthesis of the impact of MACSF on N2O emissions. By identifying the key controlling factors, the findings serve to guide the development of region-specific tailored substitution strategies, considering its contribution to N2O emission mitigation.
期刊介绍:
Field Crops Research is an international journal publishing scientific articles on:
√ experimental and modelling research at field, farm and landscape levels
on temperate and tropical crops and cropping systems,
with a focus on crop ecology and physiology, agronomy, and plant genetics and breeding.