干旱区瓜田不同压砂覆盖对土壤水分蒸发的影响及回归模型

Effect of different gravel covering on soil water evaporation and regression model in arid areas melon fields

为研究干旱区瓜田不同压砂覆盖对土壤水分蒸发量的影响,设置在土壤表层裸露和覆盖砾石、覆盖砾石厚度不同、粒径不同以及覆盖砾石年限不同的处理,采用土柱蒸发称重法测量土壤水分蒸发量,并对土壤水分累积蒸发量进行线性回归、二次多项式回归、乘幂回归拟合。结果表明,从西瓜生长到成熟期,压砂地累积水分蒸发量的增加只有裸地的29.3%,压砂覆盖可以明显减少土壤水分蒸发量。土壤表面压砂覆盖越厚,抑制蒸发效果越好,考虑经济性和利用率,覆盖厚度10~15 cm时抑制土壤水分蒸发效果最优。覆盖砾石粒径越小,抑制蒸发效果越好,综合考虑持水性和取材经济性,采用粒径30~50 mm的砂石覆盖土壤最适宜。压砂覆盖年限不同,土壤的蒸发量和含水量也不同,压砂3 a(年)土壤的含水量最高,随着压砂年限增加到5 a以上,土壤含水量降低。二次多项式回归拟合模型能更好地模拟预测不同压砂覆盖下土壤累积蒸发量,回归拟合度R2均大于0.98。

In order to study the evaporation effect of different gravel cover on the melons field in the arid area,the soil surface was covered with gravel with different thickness,different particle size,and different coverage age.The evaporation was measured by soil column evaporation weighing method.Results showed that:(1)During watermelon growing to maturity,the cumulative evaporation of covered gravel land increased by only 29.3%of bare land,and covered gravel could significantly reduce soil water evaporation.(2)The thicker gravel is covered on the surface of soil,the better the evaporation inhibition effect.Considering the economy and utilization rate,the effect of inhibiting soil water evaporation is optimal when the covered gravel is 10-15 cm.(3)The smaller the particle size of covered gravel,the better the evaporation inhibition.Considering the water holding capacity and the economy of sampling,it is most suitable to cover the soil with sand and gravel with diameter of 20-50 mm.(4)The age of covered gravel is different,the evaporation and water content of soil are also different.The soil moisture content is the highest in covered gravel for 3 years,and the soil water content decreases with the age of covered gravel not less than 5 years.(5)Quadratic regression fitting model can better simulate and predict soil evaporation under different gravel mulches.The regression fitting degree R2 is greater than 0.98.