Effects of Irrigation Regime and Nitrogen Fertilizer Management on CH4, N2O and CO2 Emissions from Saline–Alkaline Paddy Fields in Northeast China

Jie Tang,Sining Wang,Zhaoyang Li,Yunke Qu,Jingjing Wang

doi:10.3390/su10020475

Abstract

Irrigation regime and fertilizer nitrogen (N) are considered as the most effective agricultural management systems to mitigate greenhouse gas (GHG) emissions from crop fields, but few studies have involved saline–alkaline paddy soil. Gas emitted from saline–alkaline paddy fields (1-year-old and 57-year-old) was collected during rice growing seasons by the closed chamber method. Compared to continuous flooding irrigation, lower average CH4 flux (by 22.81% and 23.62%), but higher CO2 flux (by 24.84% and 32.39%) was observed from intermittent irrigation fields. No significant differences of N2O flux were detected. Application rates of N fertilizer were as follows: (1) No N (N0); (2) 60 kg ha−1 (N60); (3) 150 kg ha−1 (N150); and (4) 250 kg ha−1 (N250). The cumulative emissions of GHG and N fertilizer additions have positive correlation, and the largest emission was detected at the rate of 250 kg N ha−1 (N250). Global warming potential (GWP, CH4 + N2O + CO2) of the 57-year-old field under the N250 treatment was up to 4549 ± 296 g CO2-eq m−2, approximately 1.5-fold that of N0 (no N application). In summary, the results suggest that intermittent irrigation would be a better regime to weaken the combined GWP of CH4 and N2O, but N fertilizer contributed positively to the GWP.

Highlights

The burgeoning population and increasing future rice demands have created tremendous concerns about agricultural greenhouse gas (GHG) emissions, which account for about one-tenth of total global anthropogenic GHG emissions [1]
The largest average flux appeared in the booting stage, i.e., 1.70 ± 0.16 mg m−2 h−1 (1-year-old, Continuous flooding irrigation (CF)) and 1.25 ± 0.25 mg m−2 h−1 (1-year-old, IF), but the lowest mean value was observed in the green period
CH4 was sensitive to irrigation regimes during booting, heading and mature stages, which was susceptible to tillage year (Table 2)

Summary

Introduction

The burgeoning population and increasing future rice demands have created tremendous concerns about agricultural greenhouse gas (GHG) emissions, which account for about one-tenth of total global anthropogenic GHG emissions [1]. The greenhouse warming potential (GWP) of rice crop fields is approximately 4.6 times and 1.6 times that of wheat and maize, respectively [2]. CO2, which serves as the major greenhouse gas contributor, supplies 60% of the greenhouse effect from humans, CH4 and N2O contribute 15% and 5%, respectively [5]. In the global warming potential for the one hundred year horizon in terrestrial ecosystems, the contribution of CH4 and N2O is 25 and 298 times larger than CO2 respectively [6]. Water regimes and N fertilizer application affect soil moisture, nutrient content and the soil’s physicochemical properties and could be effective crop management tools to mitigate GHG emissions

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Conclusion