Growth Characteristics Of Sloping Grop Roots And Its Effects On Runoff And Sediments

Soil erosion is paid more and more attention in the Loess Plateau, as one of importantenvironment problems in China. Cultivation on sloping land is the major source of soilerosion of the Loess Plateau, which is one of the main factors in limiting the developmentof economy and society in local area. On the other hand, cultivation on sloping landthreatens the security in downstream area due to flood and non-point pollution. Cropsdetermine the economic benefit and ecological benefit, as the key factor of influence on thesoil and water loss. The root growth of crops affect the crop aerial part and yield. Thus, toimprove the estimation of crop function and to operate agricultural production scientifically,the relationship between crop root and soil erosion were studied. In our study, the laws ofrunoff and sediment caused under the cover of corn on plot were studied, as well theinfluence of corn root on soil anti-erodibility, soil anti-scourability and soil shearingresistance were studied, which were conducted by using rainfall simulating experiment,hydrostatic disintegrating method the undisturbed soil trough scouring method anddetermination of shear resistance. Main results are as follows:1. Under the rainfall simulating experiments on the soil bins, we found the corn androots had the erosion resistance, with the erosion resistance increasing as the leaf area indexincreasing. The runoff varied as the following order: T1(CK)>T2(Corn root)>T3(Cornplant), the sediment varied as the same pattern. During the process of generating of runoffand sediment, corn plant can delay the times of generation and peak values of runoff andsediment, while corn root only affect the sediment yield slightly.2. Under the rainfall simulating experiments on the field runoff plots, results showedthat both corn plant and corn root played a positive role in reducing runoff and sediment.The efficiency of runoff and sediment reduction under the T3treatment is higher than thatunder the T2treatment, which agrees with the results under the rainfall simulatingexperiments on the soil bins. The runoff are16.74%and54.17%lower in the T2and T3treatments compared to the T1treatment respectively, while the sediment are47.74%and79.66%lower in the T2and T3treatments compared to the T1treatment respectively.3. Corn root can improve the soil anti-erodibility. The relationship between soil disintegration rate and soil depth in the T1treatment (CK) is negative, with the soildisintegration rate declining as the soil depth increasing. Besides, the influence of corn rooton the soil anti-erodibility varied with the growth of corn root during different growthstages. Corn root can increase the soil anti-erodibility up to45%approximately in the0-10cm soil layer, with32%for the10-20cm soil layer. The process of soil disintegration issteady, of which the time to remain steady is shorter compared to the ones under the CKtreatment.4. The influence of corn root on soil anti-scourability is significant. The relationshipbetween soil water pre-wash and soil anti-scourability coefficient is significant in the CKtreatment. The relationship between soil water pre-wash and soil anti-scourabilitycoefficient is not significant in the corn root treatment, while the relationship betweenamount of corn root and soil anti-scourability coefficient is significant. The soil water ismore homogeneous in the corn root treatment than the one in the CK treatment.5. The relationship between soil anti-scourability and soil depth is positive, while therelationship between soil anti-scourability and slope angle is negative. During each corngrowth stage, The soil anti-scourability of different soil layers is stronger under the cornroot treatment than the one under the CK treatment.