秸秆与地膜覆盖春玉米和春小麦耕层土壤碳氮动态

Dynamics of soil carbon and nitrogen in plowed layer of spring corn and spring wheat fields mulched with straw and plastic film

采用田间试验研究了秸秆和地膜覆盖处理春玉米和春小麦生育期耕层土壤有机碳、全氮和硝态氮的动态变化。结果表明:秸秆覆盖处理明显提高了春玉米和春小麦生育期土壤有机碳含量,而地膜覆盖处理土壤有机碳含量呈下降趋势;灌溉同时降低了春小麦地膜覆盖处理土壤有机碳的降低幅度和秸秆覆盖处理土壤有机碳的增加幅度;秸秆和地膜覆盖处理土壤全氮与硝态氮含量在春玉米和春小麦生育期的动态变化都呈"增加-降低-增加"的趋势,但土壤全氮变化幅度较小,处理间差异不显著,而硝态氮变化剧烈,处理间差异达显著或极显著水平;灌溉对不同覆盖处理春小麦生育期土壤全氮含量影响较小,但灌溉显著降低了不同覆盖处理春小麦拔节期土壤硝态氮的增加幅度。

Field experiments were conducted to study the dynamics of soil organic carbon, total nitrogen and nitrate in plowed layer of spring corn and spring wheat fields under straw and plastic film mulching. The results indicate that straw mulching significantly increases soil organic carbon content during growth periods of spring corn and spring wheat. However, organic carbon content decreases under plastic film mulching. Irrigation reduces both the decline degree under plastic film mulching treatment, and the increase degree in straw mulching treatment of soil organic carbon during the growth periods of spring wheat. Soil total nitrogen and nitrate contents show ＂increase-decrease-increase＂ trend under both straw and plastic film mulching during growth periods of spring corn and spring wheat. However, the change range in soil total nitrogen, which is not significantly different among treatments, is much smaller than that in soil nitrate, which is significantly different among treatments. The effect of irrigation on soil total nitrogen content is insignificant for all mulching treatments during growth period of spring wheat, but it significantly limits the degree of increase in soil nitrate for all mulching treatments at jointing stage of spring wheat.