园林废弃物覆盖组分及厚度对土壤水分物理性质的影响

Comparison of hydraulic properties of soils mulched by different garden wastes

【目的】探索园林废弃物的不同组分、覆盖厚度对土壤水分物理性质的影响。【方法】对园林废弃物按照草屑、树叶、枝叶混合物、树枝4类不同覆盖材料进行分类,经预处理后按3、6 cm和9 cm的覆盖厚度设置覆盖组分及厚度的二因素园林废弃物覆盖栽培试验。经过21个月的培养后,测定土壤体积质量、孔隙度、通气度、持水量、排水能力,对各指标进行单项分析并运用因子分析法进行综合评价。【结果】园林废弃物用于地表覆盖可有效改善土壤水分物理特性,改善效果因覆盖材料类型和覆盖厚度而异。与裸土对照相比,覆盖条件下的土壤体积质量显著降低了5.6%~13.6%,土壤孔隙度显著增加了25.2%~82.9%,土壤最大持水量显著增加了31.9%~108.2%,毛管持水量显著增加了36.7%~114.2%,田间持水率显著增加了64.1%~149.8%,土壤排水能力显著增加了38.2%~67.1%。通过综合评价筛选出6种适宜改善土壤水分物理性质的不同园林废弃物组分与覆盖厚度组合模式,分别为9cm树叶、9 cm草屑、9 cm枝叶、6 cm草屑、6 cm树叶及9 cm树枝。【结论】园林废弃物覆盖可有效降低土壤体积质量、改善土壤孔隙度和排水特性,从而提升土壤水源涵养能力,但在实际应用中需注意选择适宜的覆盖材料类型和覆盖厚度。

【Background and Objective】Organic mulch involves covering the soil surface with organic materials.While it has been recognized as an environmentally friendly method for reusing organic waste,improper mulching with organic wastes might degrade soil structure,hinder vegetation growth,and lead to environmental pollution.This paper is to investigate the alterations in soil hydraulic properties resulting from various garden waste mulches.【Method】The study is based on incubation.Garden wastes including grass clippings,tree leaves,tree branches,and branch-leaf mixtures are used to mulch the soil surface at a thickness ranging from 3 to 9 cm.The incubation lasts 21 months,after which we measure soil moisture content,bulk soil density,soil porosity,soil aeration,water holding capacity,and soil hydraulic conductivity.Their variations with the garden waste types and the mulching depth are analyzed.【Result】①Mulching with all garden waste types increases soil hydraulic properties,albeit the improvement depends on the waste types and mulching thickness.②Compared to without mulch,mulching reduces soil bulk density significantly by 5.6%-13.6%,increases the maximum soil water holding capacity by 31.9%-108.2%,capillary water holding capacity by 36.7%-114.2%,field water holding capacity by 64.1%-149.8%,and drainage capacity by 38.2%-67.1%.③Comprehensive evaluation reveals that those that were effective for improving hydraulic properties of soil are:9 cm tree leaves,9 cm grass clippings,9 cm branch leaves,6 cm grass clippings,mixture of 6 cm branch leaves and 9 cm tree branches.【Conclusion】Mulching soil with garden wastes can increase soil porosity and drainage capacity,thereby improving water-holding capacity of the soil.However,care needs to be taken in selecting waste types and mulching thicknesses in practical application in order to optimize mulching benefits.