Dynamic Simulation Of Water Content And Penetration Resistance In Red Soil Root-zone Under Different Fertilization

Large density of clayey red soil,high clay content,once the moisture content is reduced,penetration resistance will increase sharply,thereby affecting the crop root elongation, water uptake and drought resistance.Master the red soil penetration resistance and topsoil moisture conditions,help predict the effects on crop growth.Based on field observations,with the model simulates the dynamic changes of the topsoil moisture and penetration resistance in red soil under four long-term fertilization systems,provide the basis for revealing field crop water relations in the red soil.Field trials conducted between in July to September2013,since1996,in the16village,set of four different fertilization,including1)CK treatment without fertilization,2)NPK fertilizer treatment,3)PCM manure treatment,4)fertilizer plus straw NPKM treatment.Crop is the Summer corn Zhengdan958.Observed meteorological data,soil moisture (10cm、20cm、30cm、40cm),water movement parameters and crop growth indicators in regular. With Hydrus model and predictive models of soil penetration resistance,simulated moisture and dynamic resistance in red soil during corn growing period,got the following results:Under four different fertilization,the evaluation of simulation of soil moisture which is predicted by Hydrus model show its all of the determination coefficient greater than0.5,some up to0.8.The absolute value of the relative errors are less than10%.Most RMS error is less than0.03cm3/cm3,under the condition of natural environment factors in greater change,the remaining layers of soil moisture simulation basically reached the desired effect except the soil surface is slightly poor simulation.Under various fertilization treatments,simulation of the effect in no rain period is better than in rainfall period.The soil penetration resistance values which is measured by resistance prediction model,The simulation evaluation results show the simulated determination coefficients are above0.5,showing that simulation result is better too.Similarly under various fertilization treatments,simulation of the effect in no rain period is better than in rainfall period.The results show that the applicability of Hydrus model and soil resistance prediction model Q=aθb in red soil plow layer.Different fertilizer treatments have a significant effect on soil moisture.In periods of soil moisture reducing,PCM manure treatment and fertilizer plus straw NPKM treatment make the soil moisture of0-10cm increases,but the fertilizer NPK treatment makes smaller water content. Three kinds of fertilizer treatments were making10-20cm soil moisture increases,while have influence on20-40cm soil layer are on no obvious law.In the rainfall is relatively concentrated, high soil moisture period,fertilization had no significant effect on soil moisture.The size of the different fertilizer treatments on soil penetration resistance was decreased with soil depth,emerging significant nonlinear negative.The resistance of the soil distributed in the soil profile showed an increasing trend,and with the increase of soil difference between treatment increasing. And the difference between treatments increased with the increase of soil.Differences between the four different fertilizer treatments significantly,in periods of rainfall,fertilizer plus straw NPKM treatment make soil penetration resistance becomes smaller sharpest,PCM manure treatment followed.From the aspects of dynamic of changes in soil resistance,three fertilization treatments have reduced soil penetration resistance’s volatility in0-10cm and20-40cm soil layer,while make the soil penetration resistance’s volatility in10-20cm soil layer increases.and the red soil penetration resistance of the soil is the largest level.Fertilizer plus straw NPKM treatment on the volatility of penetration resistance is the maximum,PCM and NPK treatment in that order.