地膜和秸秆覆盖对冻融期土壤硝态氮迁移与分布的影响

Effect of mulching on the migration and distribution of soil nitrate nitrogen during freezing-thaw period

为了揭示地面覆盖对冻融期土壤硝态氮迁移与分布的影响,试验分别设置裸地(LD)、地膜覆盖(MD)和秸秆覆盖(JD)3种地表处理,运用单因素方差分析(one-way ANOVA)和最小显著差异法(LSD)统计分析冻融期土壤硝态氮的时空变化规律。结果表明,封冻前地表覆盖(MD和JD)显著增加了土壤剖面(0~110cm)的硝态氮质量比,土壤硝态氮的累积效果为MD>JD>LD;冻结期各处理地块均在土壤相变区(0~60cm)出现硝态氮质量比高值区,LD在土壤冻结过程中的积氮效应(特指硝态氮)最为显著,积氮范围为10~55cm,硝态氮质量比峰值达37.18mg/kg,显著高于MD和JD;消融期MD显著增加土壤剖面硝态氮质量比,最高值达42.38mg/kg。MD和JD有效抑制了冻融期相变区土壤硝态氮质量比的波动程度,其中JD硝态氮质量比的时程变幅小于MD。同时,冻融期MD与LD间硝态氮质量比均差值明显高于JD,且土体通融后,MD、JD和LD为0~60cm土壤硝态氮质量比与封冻前相比分别增加了12.23、6.84和6.57mg/kg,说明MD更有利于硝态氮累积。

In order to evaluate the influences of surface mulching on soil nitrate content during freezing-thaw period, nitrate trans-fer experiment was performed during a freezing-thaw period with the treatments of straw mulching （JD） , plastic film mulching （MD）,and no mulching （LD）. Analysis of variance（one-way ANOVA）and least significant difference（LSD） was employed to sta-tistically analyze the temporal and spatial variation of soil nitrate nitrogen The results showed that surface mulching （MD and JD） significantly increased the nitrate nitrogen content in soil profile （0-110 cm） , and the cumulative effect of nitrate nitrogen was MD〉JD〉LD. During the freezing period, the high value area of the nitrate nitrogen content in phase change zone （0-60 cm） oc-curred and the LD cumulative effect was most significant. Nitrate nitrogen content at 10-55 cm was 37. 18 mg/kg, which was sig-nificantly higher than that of MD and JD. In the ablation period, MD could increase the nitrate nitrogen and the maximum value was 42. 38 mg / kg. MD and JD can effectively weaken the fluctuation degree of phase change zone in seasonal freezing-thaw peri-od and the variable amplitude of JD was less than MD. Meanwhile, the mean difference between MD and LD was significantly higher than JD. Compared with initial time, the soil nitrate content of MD, JD and LD increased by 12. 23？ 6. 84 and 6. 57 mg/ kg, respectively, which indicated the plastic film treatment was more conducive to the decomposition and release of available ni-trogen