Effects Of Film Thickness And The Time To Remove The Film On The Growth Of Spring Maize And The Recovery Of Residual Film In Dry Farmland

Plastic film mulching plays an important role in promoting spring maize production in the northwest dry farming areas.However,the thickness of agricultural film used in production is generally lower than the national standard(0.010 mm),and the film is traditionally removed after corn is harvested,which makes it difficult to recycle the residual film,resulting in serious environmental pollution problems.Based on this,this experiment conducted two consecutive spring corn field experiments at the Changwu Loess Plateau Agro-ecological Experiment Station of the Chinese Academy of Sciences from2020 to 2021.A two-factor randomized block design was used to set three film thicknesses:0.008 mm(H1),0.010 mm(H2),0.012 mm(H3),and two film removal periods: tasseling period(T1)and after harvest(T2),a total of six treatments,analyzed the effects of different film thickness and the time of removing the mulch film on farmland soil physicochemical,spring corn growth,film recovery rate and final economic benefits,aiming to explore the optimal film thickness and the time of removing the mulch film,for the purpose of Provide theoretical basis for optimizing field mulching management in dry farming areas.The main research results are as follows:(1)The thickness of the mulch film and the time of removing the mulch film affect the soil water temperature and nutrient conditions.Compared with 0.008 mm and 0.010 mm,0.012 mm of plastic film increased the soil water content in the early growth stage of spring maize and the soil water storage in the 0-200 cm soil layer,and significantly increased the soil temperature in the 5 cm and 15 cm soil layers in the early growth stage of spring maize.In addition,compared with 0.008 mm and 0.010 mm,0.012 mm of plastic film increased the nitrate nitrogen content of the surface soil.Compared with removing plastic film after harvesting,removing plastic film during tasseling period reduced the soil water content and water storage in the late growth stage of spring maize,and significantly reduced the soil temperature in the 5 cm and 15 cm soil layers in the late growth stage of spring maize,increased the contents of soil organic matter,available nitrogen and available phosphorus in the 0-20 cm soil layer in the mature stage.(2)The thickness of the mulch film and the time of removing the mulch film significantly affect the growth of spring maize.Compared with 0.008 mm and 0.010 mm,mulching with 0.012 mm increased the plant height,leaf area index and dry matter accumulation of spring maize,and increased the nitrogen accumulation and total nitrogen accumulation in roots,stems and leaves during tasseling stage.Compared with removing plastic film after harvesting,removing plastic film during tasseling period improved the leaf area index and dry matter accumulation.Removing plastic film during tasseling period alleviated the premature senescence caused by high temperature in the late growth stage of spring maize,and improved the SPAD value,net photosynthetic rate,transpiration rate and stomatal conductance of ear leaves at the grain filling stage of spring maize,increased nitrogen accumulation and total nitrogen accumulation in stems,leaves and grains during mature stage.(3)The thickness of the mulch film and the time of removing the mulch film significantly affected the yield and water use efficiency of spring maize.Compared with0.008 mm and 0.010 mm,mulching with 0.012 mm increased the grain yield of spring maize by 4.74%-14.72% and 1.31%-4.11%,respectively;compared with removing plastic film after harvesting,removing plastic film during tasseling period increased the grain yield by 9.90%-18.80%.Compared with 0.008 mm and 0.010 mm,mulching with 0.012 mm improved the water use efficiency of spring maize by 4.39%-16.66% and 0.82%-4.67%,respectively;compared with removing plastic film after harvesting,removing plastic film during tasseling period improved the water use efficiency by 5.03%-15.71%.The thickness of the mulch film and the time of removing the mulch film had no significant effect on the nitrogen use efficiency.(4)The thickness of the mulch film and the time of removing the mulch film are closely related to the recovery rate of the mulch film.Compared with 0.008 mm and 0.010 mm,mulching with 0.012 mm increased the mulching film recovery rate by13.76%-17.84% and 6.02%-8.83%,respectively.Compared with removing plastic film after harvesting,removing plastic film during tasseling period increased the mulching film recovery rate by 6.69%-11.71%.In terms of net profit,mulching with 0.012 mm was significantly higher than that of 0.008 mm and 0.010 mm,and removing plastic film during tasseling period was significantly higher than that after harvesting.The comprehensive analysis shows that compared with the commonly used0.008～0.010 mm plastic film mulching in production,mulching with 0.012 mm plastic film has obvious effect of increasing temperature and moisture content,promoting the growth of spring maize,and improving the grain yield and economic benefits of spring maize.Compared with the actual production of spring maize after harvesting,removing plastic film during tasseling period reduces the soil temperature in the late growth stage of spring maize,avoids the problem of premature aging caused by high temperature,alleviates the excessive consumption of soil nutrients,and significantly improves the grain yield of spring maize and economic benefits.In addition,mulching with 0.012 mm plastic film and removing plastic film during tasseling period significantly improved the mulching film recovery rate and effectively solved the problem of residual film pollution.Therefore,mulching with 0.012 mm plastic film and removing the plastic film during the tasseling period is an ideal film mulching management mode for increasing the yield and efficiency and ecological and environmental protection of spring maize in the rain-fed agricultural area of the Loess Plateau.