Short-Term Assessment of Nitrous Oxide and Methane Emissions on a Crop Yield Basis in Response to Different Organic Amendment Types in Sichuan Basin

Hamidou Bah,Lanre Anthony Gbadegesin,Kai Wei,Bo Zhu,Dayo George Oladipo,Ayodeji Medaiyese,Lei Hu

doi:10.3390/atmos12091104

Abstract

Agriculture’s goal to meet the needs of the increasing world population while reducing the environmental impacts of nitrogen (N) fertilizer use without compromising output has proven to be a challenge. Manure and composts have displayed the potential to increase soil fertility. However, their potential effects on nitrous oxide (N2O) and methane (CH4) emissions have not been properly understood. Using field-scaled lysimeter experiments, we conducted a one-year study to investigate N2O and CH4 emissions, their combined global warming potential (GWP: N2O + CH4) and yield-scaled GWP in a wheat-maize system. One control and six different organic fertilizer treatments receiving different types but equal amounts of N fertilization were used: synthetic N fertilizer (NPK), 30% pig manure + 70% synthetic N fertilizer (PM30), 50% pig manure + 50% synthetic N fertilizer (PM50), 70% pig manure + 30% synthetic N fertilizer (PM70), 100% pig manure (PM100), 50% cow manure-crop residue compost + 50% synthetic N fertilizer (CMRC), and 50% pig manure-crop residue compost + 50% synthetic N fertilizer (PMRC). Seasonal cumulative N2O emissions ranged from 0.39 kg N ha−1 for the PMRC treatment to 0.93 kg N ha−1 for the NPK treatment. Similar CH4 uptakes were recorded across all treatments, with values ranging from −0.68 kg C ha−1 for the PM50 treatment to −0.52 kg C ha−1 for the PM30 treatment. Compared to the NPK treatment, all the organic-amended treatments significantly decreased N2O emission by 32–58% and GWP by 30–61%. However, among the manure-amended treatments, only treatments that consisted of inorganic N with lower or equal proportions of organic manure N treatments were found to reduce N2O emissions while maintaining crop yields at high levels. Moreover, of all the organic-amended treatments, PMRC had the lowest yield-scaled GWP, owing to its ability to significantly reduce N2O emissions while maintaining high crop yields, highlighting it as the most suitable organic fertilization treatment in Sichuan basin wheat-maize systems.

Highlights

Greenhouse gas (GHG) emissions from agricultural ecosystems continue to remain a major source of concern due to agriculture’s net contribution to global radiative forcing
The findings were consistent with the results reported by Nyamadzawo et al (2017) and Mukumbuta et al (2017), who noted that partial substitution of organic amendments resulted in lower N2O in organic amended soils when compared to full synthetic N fertilizer treatments [63,64]
This paper explores the effects of organic amendment types and increasing differential manure N ratios on greenhouse gas emissions, global warming potential (GWP) and yield-scaled GWP in a wheat-maize system in southwest China as well as the drivers controlling greenhouse gas emissions

Summary

Introduction

Greenhouse gas (GHG) emissions from agricultural ecosystems continue to remain a major source of concern due to agriculture’s net contribution to global radiative forcing. In order to overcome the triple issues of food sustainability, environmental degradation, and global warming, the application of organic amendment on farmlands could present the opportunity to reduce the intensive reliance on synthetic fertilizers, protect the environment, further improve crop yields, retain soil fertility, and mitigate GHG emissions [3,5]. China produces about 3.8 Tg of manure annually, which has the potential of generating up to 262 billion RMB (40.5 billion USD) in yearly revenue and can satisfy its current nitrogen (N) demands by as much as 50% [7,8]. Zhou et al (2013) have found out that organic amended soils could produce yields similar to that of the conventional N fertilizer treatments in Sichuan wheat-maize systems [5]. Yao et al (2009) observed that applying organic amendments could decrease GHG emissions by up to 32% compared to conventional N fertilizers while showing the same, or even an increase in crop yields with respect to conventional N fertilizer treatments [11]

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