植株影响下大豆农田土壤水分对降雨的响应模型研究

Simulation of Soil Water Infiltration in Soybean Field During Rainfall

为了研究植株影响下大豆农田土壤水分含量对降雨的响应模型,在野外开展对比试验与模型模拟研究.实验设计测定裸土、去除地上茎叶、保留地上茎叶条件下土壤水分湿润峰在降雨过程中的迁移和鼓粒期大豆根系形态.结果表明,研究区单次降雨湿润峰主要集中在015cm土层中,下移深度未触及犁底层.在大豆植株截留传导及根系促进入渗影响下,进行土壤水分研究时,需将大豆耕地土壤水分入渗划分为两个区域,即大豆植株影响区域和无影响区域.垄间区域为无影响区域,土壤水分入渗按照裸土考虑,植株周围及株间不同于垄间为植株影响区域,需要考虑植株截留传导及根系促进入渗的影响.在研究区,采用实测植株周围土壤饱和导水率0.028cm·min^(-1)代替裸土土壤饱和导水率0.021cm·min^(-1)作为模型参数,利用Richard模型进行土壤含水量模拟,3次模拟值与实测值RMSE分别为0.99%、0.94%和1.16%,产流时刻误差0.77、1.12和0.82min,模拟精度较高,说明利用实测植株周围土壤饱和导水率代替裸土土壤饱和导水率,Richard模型可以作为研究区植株影响下大豆农田土壤水分对降雨的响应模型.

We conducted field tests and model simulations to evaluate the influence of soybean plants on the response of soil-water content to rainwater. We designed experiments to determine the migration of the wetting peak during a rain and the morphology of soybean roots during the seed- filling stage for bare soil, soil near plants with from a single rain was mainly concentrated in 0 and without stems and leaves. The wetting peak 15 cm soil layer and did not reach the plough pan. Under the influence of interception and transmission of soybean plants and root system promotion, the soybean cultivated was divided into soybean plant affected area （plants around） and unaffected area （ridge area）. The interception of rainwater by the plants and the influence of roots promoting infiltration need to be considered for the soil near the plants but not for the ridges. The saturated hydraulic conductivity of the surface soil was 0. 028 cm. min -＇ near plants （Ac ） and 0. 021 cm-min- t for bare soil （Bc ）, which were applied as parameters in Richards＇ equation for simulating the transfer of soil moisture during a rain. The root mean square errors were O. 99% ,0. 94% ,and 1.16% between the measured and simulated values for soil moisture and 0. 77,1.12 ,and 0. 82min for the times to the onset of runoff for 3 treatments ,respectively. The measured and simulated values agreed well, suggesting that using Ac in Richards＇ equation could model the response of soil moisture to rain near the soybean plants better than using Bc.