N2O and NO Emissions as Affected by the Continuous Combined Application of Organic and Mineral N Fertilizer to a Soil on the North China Plain

Deyan Liu,Heyang Sun,Tiehu He,Jiafa Luo,Xia Liao,Weixin Ding,Stuart Lindsey,Junji Yuan,Mohammad Zaman

doi:10.3390/agronomy10121965

Abstract

A field experiment was conducted to evaluate the influence of the continuous application of organic and mineral N fertilizer on N2O and NO emissions under maize and wheat rotation on the North China Plain. This study included eight treatments: no fertilizer (control); mineral N fertilizer (Nmin) at a rate of 200 kg N ha−1 per season; 50% mineral fertilizer N plus 50% cattle manure N (50% CM), 50% chicken manure N (50% FC) or 50% pig manure N (50% FP); 75% mineral fertilizer N plus 25% cattle manure N (25% CM), 25% chicken manure N (25% FC) or 25% pig manure N (25% FP). The annual N2O and NO emissions were 2.71 and 0.39 kg N ha−1, respectively, under the Nmin treatment, with an emission factor of 0.50% for N2O and 0.07% for NO. Compared with the Nmin treatment, N2O emissions did not differ when 50% of the mineral N was replaced with manure N (50% CM, 50% FC and 50% FP), while annual NO emissions were significantly reduced by 49.0% and 27.8% under 50% FC and 50% FP, respectively. In contrast, annual N2O emissions decreased by 21–38% compared to the Nmin treatment when 25% of the mineral N was replaced with manure N (25% CM, 25% FC and 25% FP). Most of the reduction occurred during the maize season. The 25% CM, 25% FC and 25% FP treatments had no effect on NO emissions compared to the Nmin treatment. There was no obvious difference in annual N2O and NO emissions among the organic manures at the same application rate, probably due to their similar C/N ratio. Replacing a portion of the mineral fertilizer N with organic fertilizer N did not significantly affect crop grain yield, except for the 50% FC treatment in the wheat season. Overall, the results suggest that the combined application of 25% organic manure N plus 75% mineral fertilizer N had the most potential to mitigate N2O emissions while not affecting crop yield in the maize and wheat rotation system in this area of China.

Highlights

Nitrous oxide (N2 O) is a trace and stable greenhouse gas and has a global warming potential (GWP) 298 times higher than CO2 on a centennial scale [1]
This study provided important insights into the effects of the types and application rates of organic fertilizers on N2 O and Nitric oxide (NO) emissions in a clay loam soil
Were lower than 1, suggesting that denitrification was the dominant process for N2 O production

Summary

Introduction

Nitrous oxide (N2 O) is a trace and stable greenhouse gas and has a global warming potential (GWP) 298 times higher than CO2 on a centennial scale [1]. Agronomy 2020, 10, 1965 in 2017, representing a 122% increase on the pre-industrial (before 1750) levels [3], and it continues to increase at a rate of 0.73 ± 0.01 ppb yr−1 [4]. Nitric oxide (NO) is one of the main sources of air pollution. It is involved in the formation of stratospheric ozone and leads to the formation of photochemical smog and acid rain [1]. Poor fertilizer practices have caused a series of environmental problems, such as the chemical degradation of soil, the contamination of air and water, and large gaseous losses of N2 O and NH3 [9,10]. N2 O and NO emissions from agricultural soils are largely caused by N inputs including mineral N fertilizer [11,12]

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Discussion

Conclusion