滴灌对干旱区春小麦田土壤CO2、N2O排放及综合增温潜势的影响

对比新疆干旱区滴灌和传统灌溉对春小麦田土壤CO_2和N_2O排放通量及综合增温潜势的影响差异,旨在为该区有利于农田温室气体减排的农业管理措施的制定提供科学依据。在春小麦田中,设置滴灌和漫灌两种灌溉方式(其中滴灌包含滴灌管间和滴灌管上2个不同的空间处理),利用静态暗箱-气相色谱法对两种灌溉方式下不同处理的土壤CO_2及N_2O排放通量及影响因素进行了测定和分析。结果表明:在春小麦生长季,滴灌方式下土壤CO_2排放通量均值比漫灌减少了35.76%。滴灌管间和滴灌管上两个处理的土壤CO_2排放通量无显著差异,均值分别为906.28、838.25 mg·m~(-2)·h~(-1),但均与漫灌处理有显著性差异(P0.05)。滴灌方式下土壤N2O排放通量达74.81μg·m~(-2)·h~(-1),比漫灌增加25.87%。滴灌管间和滴灌管上处理土壤N_2O平均排放通量均高于漫灌,分别为85.76、63.62μg·m~(-2)·h~(-1),3个处理间均无显著性差异(P0.05)。滴灌和漫灌方式下土壤CO_2累积排放量分别为2 188.68、3180.91 g·m~(-2),土壤N2O累积排放量分别为188.62、160.60 mg·m~(-2),滴灌方式下春小麦田土壤CO_2和N_2O的综合增温潜势比漫灌减少983.55 g CO~(-2)·m~2。相关性分析表明,滴灌管间处理土壤CO_2排放通量与大气温度及5、10 cm地温的相关性均达显著水平(P0.05),与10~20 cm层土壤微生物量碳呈极显著相关(P0.01);漫灌方式下,0~10 cm和10~20 cm层土壤水分显著影响土壤N_2O排放通量(P0.05);滴灌方式下滴灌管上处理的0~10 cm层土壤水分与土壤N_2O排放通量显著相关(P0.05),滴灌管间处理的10~20cm层土壤NH_4~+-N含量是影响N2O排放通量的显著因素(P0.05)。

Effects of drip irrigation on soil CO2 and N2O emissions and their global warming potentials of spring wheat field in arid region

Drip irrigation is a new water-saving irrigation technique and is widely applied in arid region in Xinjiang. However, there is little information available about its effects on greenhouse gas emissions. In this study, a field experiment was conducted to compare the effects of both drip irrigation and conventional flood irrigation on soil CO2 and N2O emissions during the spring wheat growing season using static closechamber method. Under drip irrigation, gas sampling was performed at between the pipes(BP)and on the pipe(OP). Results showed that:average CO2 emissions under drip irrigation was 35.76%lower than that under flood irrigation during the spring wheat growing season, with significant difference. Average CO2 emissions from BP and OP were 906.28 and 838.25 mg·m-2·h-1, respectively. No differences were found between them. N2O emissions under drip irrigation was 74.81 μg·m-2·h-1 or 25.87%higher than that under flood irrigation. Average N2O emissions from OP and BP were 85.76 and 63.62 μg·m-2·h-1, respectively. However there was no significant difference between drip and flood irrigation systems(P>0.05). Cumulative emissions under drip and flood irrigations were respectively 2 188.68 and 3 180.91 g·m-2 for CO2, and 188.62 and 160.60 mg·m-2 for N2O. The global warming potentials of CO2 and N2O under drip irrigation was 983.55 g CO2·m-2 lower than that under flood irrigation. Significant correlations were observed between soil CO2 emissions from BP and air temperature, soil temperature at 5 cm and 10 cm depth(P<0.05)and soil microbial biomass carbon at 10~20 cm depth(P<0.05), and also between soil N2O emissions under flood irrigation and soil water content at 0~10 cm and 10~20 cm depth(P<0.05). Soil N2O emissions from OP were signif-icantly correlated with soil water content at 0~10 cm depth (P<0.05)and that from BP were significantly correlated with soil NH+4-N at 10~20 cm depth.