Effects Of Degradable Film Mulching On Maize Growth And Soil Environment And Optimization Of Mulching Period In West Songliao Plain

The degradable mulch film can reduce environmental pollution and increase the utilization rate of rainfall duo to its' gradually degraded in the later stage of growth,which has the same covering effect as the conventional plastic film mulching before it is degraded.To explore the optimal coverage period of the degradable mulching film in different hydrological years,which can ensure the effect of mulching on the temperature and moisture retention of crops in the early stage of growth,as well as improve the water use efficiency.This study carried out three years(2016?2018)in situ field trials in the water-saving and grain-increasing action project in the east of Inner Mongolia,based on the large-area corn drip irrigation planting in the West Songliao Plain.Three different induction periods of white oxo-biodegradable film mulching,(WM)treatment,60d(WM60),80d(WM80)and 100d(WM100);Three different induction periods of black oxo-biodegradable film mulching(BM)treatment,60d(BM60),80d(BM80)and 100d(BM100);conventional plastic film mulching treatment(PM)and bare ground(control check,CK)treatment were set.The degradation performance of Oxo-biodegradable mulch and the effects of different mulching on the soil environment,corn growth,yield and rainfall efficiency were analyzed.The HYDRUS-2D software was used to simulate the water and heat transfer laws in different induction periods,and the optimal coverage period of the degradable plastic film suitable for different hydrological years was proposed.The main research conclusions are as follows:(1)Both the Oxo-biodegradable film began to degrade around the preset induction period,indicating that the degradation time was controllable.The damage rate of Oxo-biodegradable mulch film is significantly higher than that of conventional plastic film mulching.The longer the coverage period,the smaller the damage rate.Within the Oxo-biodegradable mulch with different colors in the same induction period,the black Oxo-biodegradable film has the damage rate is 1.52%?17.01%higher than that of the white Oxo-biodegradable film mulching;the damage rate of the Oxo-biodegradable mulch on the bare surface area is higher than that of the shallow soil cover.(2)The white Oxo-biodegradable film has no significant difference in the soil accumulated temperature during the undegraded stage and conventional plastic film mulching treatment.The black Oxo-biodegradable film during the growth period reduces the soil accumulated temperature by 44.56? compared with the white Oxo-biodegradable mulch;the longer the Oxo-biodegradable film induction period,the higher the accumulated soil temperature.(3)There is no significant difference in the soil moisture content between the Oxo-biodegradable film in the undegraded stage and the conventional plastic film mulching treatment;the conventional plastic film hinders the rainfall infiltration,the tasseling period to the grouting period,and the Oxo-biodegradable film The soil moisture content in the area of the film mulching is increased by 3.99%?20.47%compared with the conventional plastic film mulching treatment;at the end of the corn growth period,the 60-day induction period of the Oxo-biodegradable film mulching has a higher soil water storage capacity than the conventional plastic film mulching treatment is 3.16%?3.22%.(4)The maximum depth of rainwater infiltration in the area covered by Oxo-biodegradable film mulching treatments is mainly affected by rainfall,mulching film damage rate,soil moisture content and distribution before rain,and all have a positive correlation.As the rainfall increases,the depth of rainwater infiltration in the mulching area becomes deeper,and the effective rainfall infiltration rate first decreases and then increases.When the rainfall reaches 89.21mm,the mulching area will no longer affect the rainfall in the mulching area.As the damage rate of the oxo-biodegradable mulch film increases,the deeper the depth of rainfall infiltration in the mulching area,the effective rainfall infiltration rate first increases and then decreases.In the West Songliao Plain,the rainfall is mainly light to moderate rain.When the rainy season(mid-to-late July)comes,the damage rate of the degradable membrane needs to reach 36.64%to achieve the optimal precipitation utilization.(5)With the increase of the induction period of the Oxo-biodegradable film mulching treatment,the soil organic matter content in the 0-60cm soil layer after harvest gradually decreases,and the soil available nitrogen content gradually increases.Before Oxo-biodegradable film treatment,the content of soil microbial biomass C and N,soil invertase,soil urease and soil catalase activities were not significantly different from those of the conventional plastic film mulching treatment,and they were all higher than the bare land control;The longer the induction period of the biodegradable film,the higher the soil microbial biomass C and N content,and the higher the activity of soil urease and sucrase.(6)There is no significant difference in the emergence rate between the Oxo-biodegradable film mulching and the conventional plastic film mulching treatment.The average emergence rate of the mulching treatment is 5.42%higher than that of the bare land treatment;the plant height,leaf area index and dry matter are not obvious at the seedling stage and jointing stage The difference,as the growth period progresses,the difference gradually decreases and increases;the growth process of the Oxo-biodegradable film mulching treatment(induction period of 60 days)is 5-6 days shorter than that of the bare ground treatment,and the growth period of the conventional plastic film mulching treatment is 2?3d.(7)Based on the yield of field trial and water use efficiency,it is recommended to choose an induction period of 60 to 80 days in normal water years and 80 to 100 days in dry years.(8)HYDRUS-2D was used to establish a soil water and heat transport model under drip irrigation under mulch.The measured data in 2016 and 2017 were used to calibrate and verify the model parameters.R2 is between 0.76 and 0.84,and the simulation results fit well with the measured data.According to the simulation results,the optimal Oxo-biodegradable film induction period in the experimental area is recommended to be about 60 days in wet years,60 to 70 days in normal water years,and 70 to 100 days in dry years.(9)Combining the results of field experiments and model simulations,it is suitable for the optimal coverage period of the Oxo-biodegradable film mulching in the West Songliao Plain.It is recommended that the damage rate reach 36.64%at about 60 days in wet years,60 to 70 days in normal water years,and 80 to 100 days in dry years.