地膜覆盖对土壤中N_2O释放的影响

Effects of clear plastic film mulching on soil N_2O discharge flux

研究地膜覆盖下土壤中N2O释放可为进一步探明膜下土壤中N2O的传输、消耗和排放到大气的动力学过程提供理论依据。在2001年3月至6月和2001年10月至2002年6月连续两个冬小麦生长季,采用静态漏斗法和揭膜—封闭箱法测定了地膜覆盖下耕层5、10、20cm土层处和地表处N2O的释放特征及相应土壤性质。结果表明:地膜覆盖下,地表和耕层10、20cm土层处N2O释放通量显著增加;0～5cm土层土壤水分和10～20cm土层土壤硝态氮的浓度的变化分别解释了休闲地和冬小麦地土壤中N2O释放通量85.23%和92.11%的变异,它们是膜下休闲地和冬小麦地土壤中N2O释放通量增加的主要原因。该结论对地膜覆盖下科学地控制农田水分、养分以及地膜覆盖在中国西北地区的科学使用和推行具有实际意义。

Study of dynamic process of soil N_2O transmitting, consuming and emitting under clear plastic film mulching needs to investigate the effects of mulching on soil N_2O discharge flux. Soil N_2O discharge fluxes by using static funnel and uncovering film-closed chamber methods and some soil properties were measured over two successive growing seasons of winter wheat, from March 2001 to June 2001 and from October 2001 to June 2002. Results showed that soil N_2O discharge fluxes measured at earth surface and at the depth of 10cm, 20cm soil layer significantly increased due to mulching compared with control. Changes of soil moisture in 0~5 cm layer and concentrations of soil nitrate in 10～20 cm layer in the fallow and the wheat fields were the reasons of the variance of soil N_2O discharge fluxes measured at earth surface by 85.23% and 92.11%, respectively, and thus they can be regarded as the main causes of the increase of soil N_2O discharge fluxes under clear plastic film mulching. These conclusions benefit to the scientific application of water and fertilizers in farmland under clear plastic film mulching and the spreading of this practice in western China for the sake of controling and reducing soil N_2O.