珍珠岩粒径对土壤水分运移的影响

【目的】探究不同粒径珍珠岩对土壤水分运移的影响。【方法】设置大(1～3 mm)、中(50～200μm)、小(<50μm)3种粒径珍珠岩处理,对其表面结构进行扫描电镜观察研究各处理的吸水及在不同温度下的保水性能;向土壤中施加大、中、小3种粒径珍珠岩,通过盆栽与土壤水分入渗试验,探究其对土壤水分的影响。【结果】通过扫描电镜观察到珍珠岩表面孔隙随粒径的减小,孔隙数量减少,且孔径也减小,小粒径(<50μm)珍珠岩不具有孔隙;通过不同温度下珍珠岩持水量测定,表明大粒径(1～3 mm)与中粒径(50～200μm)珍珠岩在常温下具有一定的吸水性和保水性,中粒径珍珠岩在3个处理中吸水量最大,保水性最好;通过盆栽试验,发现大粒径与小粒径珍珠岩能促进土壤水分的蒸发,减少土壤水分,中粒径珍珠岩在土壤中具有一定的保水性;通过水分入渗试验,发现大粒径与中粒径珍珠岩能促进土壤水分入渗,土壤累积入渗量和湿润锋深度随着珍珠岩粒径增大而减小,Horton公式拟合更适合本试验的入渗模型。【结论】不同粒径的珍珠岩对土壤水分运移影响不同。大粒径珍珠岩具有疏松土壤,增加土壤水分散失的作用;中粒径珍珠岩能良好地协调土壤水气状况,促进土壤水分入渗,并且有一定的保水能力;小粒径珍珠岩会对土壤造成不良影响,不宜作为土壤添加基质。

Water Movement in Soil Amended with Perlite Particles of Different Sizes

【Objective】The objective of this paper is to elucidate the effect of amending soil with perlite particles of different sizes on water movement in the soil.【Method】We examined three particle sizes ranging from 50 μm to 3 mm, and their surface structure was characterize by scanning electron microscopy(SEM). Water movement in the soil amended with these particles was studied experimentally by measuring water retention and movement in it at different temperatures using pot experiments.【Result】SEM revealed that the pore size on the surface of the perlite particles increased with particle size while decreased as the number of pores increased. SEM did not identified any pore for particles <50 μm. Soil amended with large(1～3 mm) and medium particles(50～200 μm) was able to adsorb water at room temperature, with the medium-size particles most effective in retaining water. It was found that amendment with large and small perlite particles enhanced evaporation thereby reducing soil moisture.Water infiltration test showed that large and medium perlite particles promoted water infiltration and the cumulative infiltration and the wetting front advancing decreased as the perlite particle size increased. The infiltration process can be described by the Horton formula.【Conclusion】Water infiltration depended on pearlite particle sizes and soil amended with large perlite particles increased soil porosity and permeability to conduct water. Medium particles improved water retention and permeability, while small particles had detrimental impact on soil and should not be used to amend soil.