地膜覆盖栽培的土壤结构与空气状况研究

Soil Air Regime and Soil Structure of the Fields under Plastic Mulching

在玉米生育期内测定了０～１００ｃｍ土层土壤空气组成、土壤通气状况的呼吸强度．结果表明，裸地上壤空气中ＣＯ２浓度为０．１％～１．６％，覆膜处理为０．２～１．８％，平均比对照高３２．３９％，尚在作物生长适宜范围内．土壤Ｏ２含量与ＣＯ２浓度变化成负相关（裸地ｒ＝０．９２，地膜ｒ＝０．７９），裸地的Ｏ２浓度变化范围为１３％～１８％，覆膜上红为１１％～１７％，覆膜低于裸地４．９６％．Ｎ２含量差异不显著．土壤呼吸强度与土壤深度呈幂函数关系，０～２０ｃｍ耕层内，覆膜土壤明显高于裸地．覆膜对土壤结构有明显影响，与裸地相比，大团聚体（＞０．２５ｍｍ）和０．０１～０．００１ｍｍ粒级微团聚体含量减少，表层０～１０ｃｍ土壤总孔隙度、气相率和通气孔隙度分别增加９．９３％、２４．５６％和３２．３０％．

The results indicated that the CO2 concentration of the unmulched soil in the 0-100cm depth ranged from 0.1% to 1.6%,and that of mulched soil was 0.2%￣1.8%.The latter was 32.39% by higher than the former on the average. Such CO2concentration in the soil air was still suitable for crop growth. The O2 rconcentration was inversely correlated with CO2 concentration in the soil air (unmulched soilr=0.92,mulched soil r=0.7).O2 concentration in the mulched and unmulched soil ranged from 11%￣17% and 13%￣18% respectively.By contrast,N2 concentration in soil air remained relatively steady,and there was no difference between the two treatments.The relationship between the soil respiratory intensity and the depth of soil layer appeared to be a power function. At the layer of 0-20cm, the soil respireation intensity in the mulched soil was obviously higher than that in the unmulchd soil. In contrast with unmulched soil, the amounts of >0.25mm and 0.05￣0.001mm microaggregates in mulched soil were reduced by 82.1% and 35.8%,respectively; soil total porosity of gaseous phase rate state and aeration porosity were increased by 9.93%,24.56% and 32.3% at the depth or 0-10cm,as compared with those of unmulched soil.