Role of organic amendment application on greenhouse gas emission from soil

Globally, substantial quantities of organic amendments (OAs) such as plant residues (3.8 × 109 Mg/yr), biosolids (10 × 107 Mg/yr), and animal manures (7 × 109 Mg/yr) are produced. Recycling these OAs in agriculture possesses several advantages such as improving plant growth, yield, soil carbon content, and microbial biomass and activity. Nevertheless, OA applications hold some disadvantages such as nutrient eutrophication and greenhouse gas (GHG) emission. Agriculture sector plays a vital role in GHG emission (carbon dioxide— CO2, methane— CH4, and nitrous oxide— N2O). Though CH4 and N2O are emitted in less quantity than CO2, they are 21 and 310 times more powerful in global warming potential, respectively. Although there have been reviews on the role of mineral fertilizer application on GHG emission, there has been no comprehensive review on the effect of OA application on GHG emission in agricultural soils. The review starts with the quantification of various OAs used in agriculture that include manures, biosolids, and crop residues along with their role in improving soil health. Then, it discusses four major OA induced-GHG emission processes (i.e., priming effect, methanogenesis, nitrification, and denitrification) by highlighting the impact of OA application on GHG emission from soil. For example, globally 10 × 107 Mg biosolids are produced annually which can result in the potential emission of 530 Gg of CH4 and 60 Gg of N2O. The article then aims to highlight the soil, climatic, and OA factors affecting OA induced-GHG emission and the management practices to mitigate the emission. This review emphasizes the future research needs in relation to nitrogen and carbon dynamics in soil to broaden the use of OAs in agriculture to maintain soil health with minimum impact on GHG emission from agriculture.

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► A comprehensive overview for the first time on GHG emission from organic amendments (OAs)
► The amounts of OAs and their carbon and nutrient value are quantified.
► The potential volumes of GHG produced from land application of OAs are quantified.
► The processes by which GHGs are emitted from soil are described.
► Management strategies to mitigate GHG emission from OAs are discussed.