Soil Erosion And Anti-Erosion Characteristics Of Peanut Land In Purple Soil Area Under Artificial Simulated Rainfall Conditions

In this study,peanut in the purple soil region of southwest China was taken as the research object.Through simulation rainfall experiment in the field,the runoff and sediment characteristics of slope surface for peanut at different growth stages(seedling stage,flowering stage,podding stage,pod maturity stage)under different rainfall intensities(60mm/h,60 mm/h,120 mm/ h)were studied.Combined with the erosion dynamics mechanism,the soil erosion characteristics were expounded.Through the study on the corrosion resistance of peanut at different growth stages,a certain theoretical basis was provided for improving the soil erosion of peanut and the sustainable development of agriculture in the region.The main research results are as follows:(1)Characteristics of runoff and sedimentUnder the condition of artificial rainfall,as the growth of peanut,the runoff generation can be effectively slow down,the runoff yield and sediment yield were significantly reduced.The runoff reduction benefit is the best at pod stage and the sediment reduction benefit is the best at pod maturity stage.The slope runoff rate increased first and then tended to be stable with rainfall,and the slope sediment yield tended to be stable from violent fluctuation with the growth of peanut.The stable runoff rate and sediment yield in each growth period showed the rule of seedling stage > flowering stage > podding stage > pod maturation stage.Larger rainfall intensity would weaken the effect of peanut on sediment yield.(2)Erosion dynamics characteristicsThe growth of peanut had good deceleration benefits for slope flow,and the deceleration benefits of each growth period were as follows: pod maturity > pod bearing >flowering > seedling stage.The Reynolds number of slope runoff in each growth period ranges from 89 to 480,which is laminar;the Froude range is 0.57 to 0.93,both belong to slow flow.The magnitudes of runoff shear force,runoff power and unit energy of section in each growth period were the same,which were in the order of seedling stage > flowering stage > pod maturity stage > podding stage.At the same growth period,with the increase of rainfall intensity,runoff shear force,runoff power and section unit energy will also increase significantly.Except seedling stage,the critical runoff shear force,critical runoff power and unit energy of critical section in each period were less than those in bare land.Moreover,the erosion dynamics parameters of each growth period showed a good linear positive correlation with the sediment yield under the corresponding conditions.The greater the rainfall intensity is,the more severe the erosion is.The growth of peanut can effectively reduce soil erosion.(3)Soil anti-erodibility characteristicsIn each growth period of peanut,the soil erosion resistance index decreased gradually with the extension of soaking time.The soil erosion resistance of 10-20 cm layer is the best.With the advance of growth period,soil anti-corrosion index increased first and then decreased in 0-10 cm soil layer,and increased first and then remained stable in10-30 cm soil layer.The non-water-stable aggregates were mainly distributed in(>5mm)grain size,and the water-stable aggregates were mainly in(<0.25mm)grain size,which showed the following order: setting > maturity > flowering > seedling stage.(4)Correlation of soil anti-erodibilityWith the advancement of peanut growth period,the stability of soil aggregates gradually increased,and the soil erosion resistance was improved.Soil erosion resistance was significantly positively correlated with > 2 mm aggregates and negatively correlated with < 0.25 mm aggregates.Soil erosion resistance increased with the increase of aggregate stability.Peanut root system is one of the important factors affecting soil aggregate stability and soil corrosion resistance.Through correlation analysis,it was found that aggregate stability was extremely significantly positively correlated with root surface area and root volume,and soil erosion resistance was extremely significantly positively correlated with root length,root surface area and root volume.The development of peanut roots was conducive to the enhancement of aggregate stability,thereby enhancing soil erosion resistance.The increase of roots <0.5mm could significantly improve the soil erosion resistance.