灌溉水盐分和灌水量对温室气体排放与玉米生长的影响

Effects of Irrigation Water Salinity and Irrigation Water Amount on Greenhouse Gas Emissions and Spring Maize Growth

摘要:

为揭示地下水与微咸水灌溉条件下灌水量对土壤CO2、N2O排放和春玉米生长的影响，设置2种灌溉水含盐量（1.1、5.0g/L）和3种灌水量（210、255、300mm），于2019年4—9月在内蒙古自治区河套灌区进行了春玉米田间试验。结果表明，不同灌水量下，微咸水（含盐量5.0g/L）灌溉比地下水（含盐量1.1g/L）灌溉土壤N2O累积排放量提高了19.86%~44.21%，但利用微咸水灌溉并不会影响土壤CO2累积排放量与全球增温潜势。在相同的灌溉水盐分条件下，灌水量为300mm时土壤CO2、N2O累积排放量和全球增温潜势均最大，灌水量为210mm和255mm时并不会对土壤CO2、N2O的累积排放量和全球增温潜势产生显著影响。相关性分析表明，土壤含水率和无机氮含量是影响土壤CO2、N2O排放的重要因素，灌溉水盐分通过促进土壤的硝化作用促进土壤N2O排放。在微咸水灌溉条件下，春玉米产量较地下水灌溉减少了30.88%~37.32%。随着灌水量的增大，春玉米产量呈增加趋势，但255mm和300mm灌水量条件下的春玉米产量差异不显著。在地下水与微咸水灌溉条件下，灌水量为255mm时，土壤盐分累积较小，春玉米产量较高，土壤CO2、N2O累积排放量和全球增温潜势相对较小，是灌区适宜采用的灌溉定额。

Abstract:

In order to reveal the effects of irrigation water amount on soil CO2, N2O emissions and spring maize growth under groundwater and brackish water irrigation, two kinds of irrigation water salinity (1.1g/L and 5.0g/L) and three kinds of irrigation water amounts (210mm, 255mm and 300mm) were set up in Hetao Irrigation District from April to September, 2019. The results showed that compared with groundwater (1.1g/L) irrigation, soil N2O emissions were increased by 19.86%~44.21% under brackish water (5.0g/L) irrigation, but irrigation water salinity did not affect soil CO2 emissions and global warming potential (GWP). Under the same irrigation water salinity conditions, cumulative CO2 emissions, cumulative N2O emissions and GWP were the largest when the irrigation water amount was 300mm, and the cumulative CO2 emissions, cumulative N2O emissions and GWP were not significantly affected by the irrigation water amount of 210mm and 255mm. The results of correlation analysis showed that soil moisture and inorganic nitrogen content were important factors affecting soil CO2 and N2O emissions, and irrigation water salinity promoted soil N2O emissions by promoting soil nitrification. The yield of spring maize under brackish water (5.0g/L) irrigation was 30.88%~37.32% lower than that under groundwater (1.1g/L) irrigation. The yield of spring maize was increased with the increase of irrigation water amount, but there was no significant difference under the irrigation water amount of 255mm and 300mm. Under the condition of groundwater (1.1g/L) and brackish water (5.0g/L) irrigation, when the irrigation water amount was 255mm, the soil salt accumulation was smaller, while the higher spring maize yield was obtained, and the cumulative CO2 and N2O emissions and GWP were relatively small, which was the suitable irrigation quota for Hetao Irrigation District.