Characteristics Of Dissolved Organic Carbon Loss From Slope Farmland In Red Soil

In order to study the response mechanism of the loss of soluble organic carbon in the sloping farmland of southern red soil to changes in external conditions,the typical red soil developed in the Quaternary red clay was selected,and artificial rainfall experiments were conducted at different growth stages of peanuts to analyze different farming methods(tillage and free Impact mechanism of rainfall intensity(60 mm / h,90 mm / h and 120 mm / h)and slope(10 ° and 15 °)on slope runoff and sand production,runoff in soil and migration of soluble organic carbon,To explore the effect of soil midstream and surface runoff on the loss of soluble organic carbon in different growth periods of peanut,to clarify the concentration and flux characteristics of soluble organic carbon lost during the runoff and sediment production,and to reveal the mechanism of soluble organic carbon loss in slope soil of red soil.This study provides a scientific basis for deepening the understanding of the relationship between soil erosion and the carbon cycle.The main findings are as follows:(1)Rainfall intensity is the main influencing factor of surface runoff and sediment,soluble organic carbon concentration and loss flux on slope soil of red soil.The surface runoff and sediment yield and soluble organic carbon loss flux increase with the increase of rainfall intensity,and the surface runoff soluble organic carbon concentration decreases with the increase of rainfall intensity.The flow of abortion,the concentration of soluble organic carbon and the flux of loss in the soil all decrease with the increase of rainfall intensity.With the extension of rainfall duration,the fluxes of soil midstream and soluble organic carbon showed a volatility downward trend,and the greater the rainfall intensity,the greater the fluctuation range.(2)The loss of soluble organic carbon in the slope soil of red soil is more susceptible to slope than surface runoff,and the effect of slope on the loss of soluble organic carbon will decrease with the extension of peanut growth period.Surface runoff and sediment yield,soluble organic carbon concentration and loss flux all increase with increasing slope,and runoff flow,soluble organic carbon concentration and loss flux in soil all decrease with increasing slope.(3)The loss of soluble organic carbon in the middle slope soil of red soil is more susceptible to farming methods than surface runoff.Under the condition of ploughing,the midstream of the soil is more prone to runoff,and the flow rate is larger.The concentration of soluble organic carbon lost is higher than that of no-tillage.The flux of soluble organic carbon loss is that ploughing is greater than no-tillage.Under the condition of ploughing,the surface runoff and sediment yield is greater than that of no-tillage,but the concentration of soluble organic carbon is less than that of no-tillage.(4)The loss of surface runoff soluble organic carbon on the slope soil of red soil is more susceptible to peanut growth than the midstream soil.The amount of sediment produced by surface runoff,the concentration of soluble organic carbon and the flux of loss are all greater in the early growth stage of peanut(seedling stage and flowering needle stage)than in the later growth stage(pod stage and mature stage).The flux of soluble organic carbon loss in soil midstream is greater than that in the later growth period of peanut.The soil midstream has less runoff in the early stage of peanut growth and a lower concentration of soluble organic carbon,but the runoff time is significantly longer than that in the middle and late period of peanut growth(5)The loss of soluble organic carbon in surface runoff and midstream of red soil slope farmland is greatly affected by external factors.The soluble organic carbon lost from surface runoff is most affected by rainfall intensity,and the farming method is least affected.The soluble organic carbon lost in the soil is most affected by farming methods and the least during the growing season.The amount of runoff and sediment produced by slope surface is most affected by rainfall intensity,and slope is least affected.Abortion and runoff in soil are most affected by slope,while growth period is least affected.The interaction between each combination of influencing factors is relatively small.Except for the surface runoff and surface runoff soluble organic carbon loss fluxes,which partially passed the significance test,the interaction between the remaining groups failed the significance test.(6)The flux of soluble organic carbon loss(95% ± 12.2%)on the surface runoff of sloping farmland in red soil is significantly greater than that of soil midstream(5% ± 12.2%).Surface runoff(97% ± 9.9% of total runoff)is significantly greater than soil midstream(3% ± 9.9%),and the concentration of soluble organic carbon(163.5 mg/L)lost with surface runoff is also significantly greater than soil midstream(40.8 mg/L).