不同水分对半干旱地区砂壤土温室气体排放的短期影响

Short-term effects of different soil moisture contents on greenhouse gas emissions from sandy loam soil in semi-arid regions

为探明不同水分条件对土壤排放温室气体的短期影响,本研究以黑龙江省半干旱地区的砂壤土为对象,通过室内培养试验研究60%田间最大持水量(WHC)、100%WHC和淹水条件下土壤中N_(2)O、CO_(2)和CH_(4)的排放规律。结果表明:与60%WHC处理相比,土壤水分含量增加至100%WHC对净硝化速率没有显著影响,但显著促进了N_(2)O的排放,平均排放速率(0.109 mg N_(2)O-N·kg^(-1)·d^(-1))是60%WHC处理(0.014 mg N_(2)O-N·kg^(-1)·d^(-1))的7.8倍。淹水处理显著抑制了硝化作用的进行,但显著促进了N_(2)O的排放,平均排放速率(0.419 mg N_(2)O-N·kg^(-1)·d^(-1))分别为60%WHC和100%WHC处理的29.9倍和3.8倍。60%WHC处理土壤CO_(2)和CH_(4)平均排放速率分别为9.92 mg CO_(2)-C·kg^(-1)·d^(-1)和2.99μg CH_(4)-C·kg^(-1)·d^(-1),土壤水分含量增加至100%WHC对CO_(2)和CH_(4)排放速率没有显著影响。淹水处理土壤CO_(2)和CH_(4)平均排放速率分别为12.7 mg CO_(2)-C·kg^(-1)·d^(-1)和5.14μg CH_(4)-C·kg^(-1)·d^(-1),显著高于60%WHC和100%WHC处理。研究表明,半干旱地区砂壤土应注意田间水分管理,避免短期淹涝,以减少温室气体排放。

To explore the short-term effects of different soil moisture conditions on greenhouse gas emissions from the soil,an incubation experiment under 60%water holding capacity(WHC),100%WHC,and flooding conditions was conducted at the laboratory to study the regularity of N_(2)O,CO_(2),and CH_(4)emissions from sandy loam soil in the semi-arid region of Heilongjiang Province,China.The results showed that increasing the soil moisture content to 100%WHC had no significant effect on net nitrification rate but significantly promoted N_(2)O emission,as compared to the 60%WHC treatment.The average N_(2)O emission rate in the 100%WHC treatment(0.109 mg N_(2)O-N·kg^(-1)·d^(-1))was 7.8 times that of 60%WHC treatment(0.014 mg N_(2)O-N·kg^(-1)·d^(-1)).Flooding significantly inhibited nitrification,whereas the emission of N_(2)O was increased to a dramatically high level with an average N_(2)O emission rate of 0.419 mg N_(2)O-N·kg^(-1)·d^(-1),which was 29.9 and 3.8 times that of the 60%WHC and 100%WHC treatments,respectively.The average emission rates of CO_(2)and CH_(4)in the 60%WHC treatment were 9.92 mg CO_(2)-C·kg^(-1)·d^(-1)and 2.99μg CH_(4)-C·kg^(-1)·d^(-1),respectively.Increasing soil moisture content to 100%WHC had no significant effect on emission rates of CO_(2),and CH_(4)in sandy loam soil.The average emission rates of CO_(2)and CH_(4)in the flooding treatment were 12.7 mg CO_(2)-C·kg^(-1)·d^(-1)and 5.14μg CH_(4)-C·kg^(-1)·d^(-1),respectively,which were significantly higher than the 60%WHC and 100%WHC treatments.The results indicate that attention should be paid to field water management for sandy loam soil in semi-arid regions,and short-term flooding should be avoided to reduce greenhouse gas emissions.