CO2 and N2O Emissions from Spring Maize Soil under Alternate Irrigation between Saline Water and Groundwater in Hetao Irrigation District of Inner Mongolia, China.

Wang Wang,Wei Wei,Xu Xu,Yang Yang,Zhang Zhang,Ren Ren,He He,Ismail Ismail

doi:10.3390/ijerph16152669

Abstract

Alternative irrigation between saline water and groundwater can alleviate shortages of available agricultural water while effectively slowing the adverse effects of saline water on the soil-crop system when compared with continuous irrigation with saline water and blending irrigation between saline water and groundwater. In 2018, we tested the effect on soil CO2 and N2O emissions by two types of irrigation regimes (alternating groundwater and saline water (GW-SW), and alternating groundwater, followed by two cycles of saline water (GW-SW-SW)) between groundwater and three levels of salinity of irrigation water (mineralization of 2 g/L, 3.5 g/L, and 5 g/L), analyzed the correlation between gas emissions and soil properties, calculated comprehensive global warming potential (GWP), and investigated the maize yield. The results show that, with the same alternate irrigation regime, cumulative CO2 emissions decreased with increasing irrigation water salinity, and cumulative N2O emissions increased. Cumulative CO2 emissions were higher in the GW-SW regime for the same irrigation water salinity, and cumulative N2O emissions were higher in the GW-SW-SW regime. The GW-SW-SW regime had less comprehensive GWP and maize yield as compared to the GW-SW regime. The 2 g/L salinity in both regimes showed larger comprehensive GWP and maize yield. The 3.5 g/L salinity under the GW-SW regime will be the best choice while considering that the smaller comprehensive GWP and the larger maize yield are appropriate for agricultural implication. Fertilizer type and irrigation amount can be taken into consideration in future research direction.

Highlights

The world’s major greenhouse gas (GHG) emissions reached a new high in 2017, with concentrations of 405.5 ± 0.1 ppm CO2 [1], 1859 ± 2 ppb CH4 [2], and of 329.9 ± 0.1 ppbN2 O [3]
The 3.5 g/L salinity under the GW-SW regime will be the best choice while considering that the smaller comprehensive global warming potential (GWP) and the larger maize yield are appropriate for agricultural implication
China is the leading GHG emitter, and CH4 and N2 O emissions from the agriculture industry are 37.59% and 74.71% of the total GHG emissions in 2008, respectively [4,5], with the CO2 emissions reaching as much as 54.16 Metric ton (Mt) in 2010 [6]

Summary

Introduction

The world’s major greenhouse gas (GHG) emissions reached a new high in 2017, with concentrations of 405.5 ± 0.1 ppm CO2 [1], 1859 ± 2 ppb CH4 [2], and of 329.9 ± 0.1 ppbN2 O [3]. The world’s major greenhouse gas (GHG) emissions reached a new high in 2017, with concentrations of 405.5 ± 0.1 ppm CO2 [1], 1859 ± 2 ppb CH4 [2], and of 329.9 ± 0.1 ppb. China is the leading GHG emitter, and CH4 and N2 O emissions from the agriculture industry are 37.59% and 74.71% of the total GHG emissions in 2008, respectively [4,5], with the CO2 emissions reaching as much as 54.16 Metric ton (Mt) in 2010 [6]. Hetao Irrigation District, which is located in the midstream of the Yellow River, is one of the three largest irrigation areas in China covering an area of 11,600 km with 500 km of saline-alkaline soil. As an arid northwest plateau of China, the area is characterized by low rainfall and high evaporation. Public Health 2019, 16, 2669; doi:10.3390/ijerph16152669 www.mdpi.com/journal/ijerph

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