残留地膜对粉壤土水盐氮运移与再分布的影响

Effects of residual mulch film on transport and redistributionof water, salt and nitrogen in silt loam soil

为探究残留地膜(以下简称“残膜”)对土壤水盐氮运移与再分布的影响,设置了不同残膜含量(0,100,200,400 kg/hm2)室内一维垂直土柱入渗-蒸发试验,测定了水分再分布过程中土壤湿润锋和各土层土壤质量含水率、电导率、硝态氮及铵态氮等指标.结果表明:残膜改变了土壤的入渗性能,当土壤中残膜量低于200 kg/hm2时,土壤湿润锋运移距离与累积入渗量均有增加;当残膜量高于400 kg/hm2时,土壤湿润锋运移距离与累积入渗量比处理CK分别减少3.59%和4.07%;随残膜含量增加,水分对盐分的淋洗效果降低,对氮肥的淋洗效果增加;残膜阻碍了盐分与硝态氮的向上运移,对铵态氮向上运移随铵态氮质量比减小由阻碍作用转变为促进作用;当残膜量高于400 kg/hm2时,土壤水分与盐分CV值比处理CK分别增加10.15%和6.51%;随残膜含量增加,硝态氮质量比CV值显著减小,不同处理土壤相同土层铵态氮质量比CV值差异较大,土壤剖面内铵态氮的变异程度无明显差异;蒸发结束时,残膜对水分蒸发的促进作用随残膜含量增加转变为阻碍作用.该研究可探明残膜污染土壤水盐氮运移与再分布规律,为含残膜农田制定合理的灌溉制度提供理论依据.

In order to explore the effects of residual mulch film(hereinafter referred to as″residual-film″)on the transport and redistribution of soil water,salt and nitrogen,an indoor one-dimensional vertical soil column infiltration-evaporation tests with different residual film contents(0,100,200,400 kg/hm 2)was set up,and the changes of soil moisture content,conductivity,nitrate nitrogen and ammonium nitrogen in each soil layer during the process of water redistribution were measured.The results show that the residual film changes the infiltration performance of the soil,and when the residual film amount in the soil is lower than 200 kg/hm 2,the soil wet peak migration distance and the cumulative infiltration rate increases.When the residual film amount is more than 400 kg/hm 2,the soil wetting peak migration distance and cumulative infiltration reduces by 3.59%and 4.07%,respectively,compared with CK treatment.With the increase of residual film content,the leaching effect of water on salt decreases,and the leaching effect on nitrogen fertilizer increases.The residual film hinder the upward transport of salt and nitrate nitrogen,and the upward transport of ammonium nitrogen changes from an obstructing effect to a promoting effect with the decrease of mass ratio of ammonium nitrogen.When the residual film amount is more than 400 kg/hm 2,the soil moisture and salt CV values increases by 10.15%and 6.51%,respectively,compared with CK treatment.With the increase of residual film content,the CV value of mass ratio of nitrate nitrogen decreases significantly,and the CV value of mass ratio of ammonium nitrogen in the same soil layer of different treated soils is quite different,and there is no obvious difference in the variation degree of ammonium nitrogen in the soil profile.At the end of the evaporation experiment,the promotion effect of the residual film on water evaporation changes into a hindering effect as the residual film content increases.This study can explore the transport and redistribution of water,salt and nitrogen in the soil contaminated by residual film,and can provide a theoretical basis for the formulation of a reasonable irrigation system for farmlands containing residual films.