Characteristics And Simulation Of Soil Moisture Dynamics In Purple Potato Field Under Different Slopes

Research the soil water condition and its variation characteristics in red soil area can carry out agricultural production more effectively and improve the yield of food crops.Based on the collected meteorological data and soil moisture data of five layers under different topographic factors during the planting period of purple potato,the climatic characteristics of the whole planting period of purple potato and the dynamics of soil moisture in five layers under different topographic factors were analyzed.At the same time,compared the five layers of soil moisture under different terrain factors of long-range correlations differences with the DFA algorithm respectively,finally to neural network model of meteorological data collected using the five layers of soil moisture under each terrain factor had carried on the simulation study,study for slope planting in the red soil region provide reference information,the main conclusions are as follows:(1)In the whole purple potato planting period,the fluctuation of meteorological factors was strong in the first three growth periods,but in the fourth growth period,the fluctuation of meteorological factors was significantly reduced and the dynamics were relatively gentle.The characteristics of air temperature,net radiation and potential evapotranspiration were similar,while the characteristics of precipitation,water vapor pressure and relative humidity were similar.Water loss was increasing throughout the study period,and water resources were most abundant in the third growth period.(2)The soil water sizes of 10 cm,20cm and 40 cm in different slopes were zone A(20°downhill)> zone C(10° downhill)> zone D(10° uphill)> zone B(20° uphill),but for 80 cm and 100 cm were zone C > zone D > zone A > zone B.As for the coefficient of variation,the coefficient of variation was close to that of the planting areas under the same depth.The variation coefficient of surface soil water was higher than that of deep soil water.Under different depth from the point of the growth period,there were still different.In the depth of10 cm,20cm,40 cm and 80 cm,the soil moisture variation coefficient was larger in the third growth period,the other three growth period was relatively close to the smaller.But in 100 cm,the first two stages of variation coefficient were smaller,after the two stages were bigger.(3)The time analysis of typical precipitation events showed that the trend characteristics of soil water dynamics were consistent with the topographic factors at the depth.Only the response time of soil water to precipitation in the planting area of 10 cm was slightly different,and the other four depths were basically same.For different depths,the response time of soil water to precipitation lagged gradually with the increase of depth.From the perspective of response degree at depths of 10 cm,20cm and 40 cm were zone A > zone C > zone D > zone B.For 80 cm and 100 cm,the change of soil water was relatively gentle.Especially before and after the end of the precipitation process,the soil moisture in each plot is basically linear,so only the increase range could be clearly seen,that was zone C > zone D > zone A > zone B.(4)There was no inflection point in the time-scale DFA characteristics calculated by each layer of soil water under different topographic factors,and all the DFA characteristics of soil water indicated that the dynamics of soil water had the characteristics of long-term correlation in the form of non-power law.The long-term correlation characteristics of soil water in the surface layer of 10 cm,20cm and 40 cm were zone A > zone B > zone C > zone D.But zone C > zone D > zone A > zone B for the depths of 80 cm and 100 cm.And the long-term correlation strength of the downhill slope was higher than that of the uphill slope under the same slope.The long-term correlation characteristics of soil water under the same slope were similar with the change of depth.(5)Among the meteorological factors selected in the study,water vapor pressure had the least impact on soil water,while precipitation,air temperature,net radiation,relative humidity and potential evapotranspiration had the greater impact on soil water.From the hysteresis effect of influencing factors on soil water,the meteorological factors had no hysteresis effect on soil water under various topographic conditions at depths of 10 cm,20cm and 40 cm,while the hysteresis effect was more obvious at depths of 80 cm and 100 cm.According to the simulation results,the simulation effect and accuracy of soil water under different topographic factors were slightly different at the same depth.With the increase of depth,the effect of soil moisture simulation under different terrain showed a gradual decline phenomenon in the precision,and 80 cm and 100 cm depth under the simulation effect were the worst,consider the weather factor hysteresis effect for soil moisture,the terrain in the depth of the two factors of soil moisture simulation accuracy had improved,but still not as good as the surface precision of simulation results.The introduction of surface soil moisture simulation value to simulate layer by layer can accurately simulate the soil moisture of 80 cm and 100 cm.