Effects Of Different Residual Film On The Growth And Soil Environment Of Maize

The promotion and application of plastic film mulching cultivation technology not only improve the yield of crops,promote the increase of agricultural production and the increase of farmers'income,but also drove the leap of agricultural productivity and accelerated the process of modern agriculture in China.However,with the increase of covering film time and area,the residual film fragments in the soil have gradually increased.Since plastic film is an extremely stable polymer material,it is difficult to decompose naturally,resulting in a large amount of residual accumulation of plastic film in the soil.In the long run,this will inevitably endanger the healthy development of China's agriculture.In this study,pot incubation test method was used for studying the impact of different quantity of plastic film residue on maize growth and development,accumulation of dry matter,root system characteristics,the resistance index,soil moisture and soil physical properties after harvest in the major growth period.In the test,in order to reveal the effects of different amount of residual film on crop growth and soil development,and provide some reference for remediation of residual film pollution,five plastic film residue levels were set:T0?0?,T1(90kg·hm^-2),T2(180kg·hm^-2),T3(360kg·hm^-2)and T4(720kg·hm^-2).The main conclusions were as follows:?1?The film remaining in the soil slows down the infiltration rate of soil moisture by changing the continuity of soil voids,and with the increase of residual film volume,the soil bulk density becomes larger and the soil porosity becomes smaller,the average soil bulk density of 0⁹0 cm was 2.03%⁴.73%higher than that of T0,and the average soil porosity decreased1.51%⁵.10%.The residual membrane also affected the distribution of soil moisture,which makes the soil moisture distribution uneven and weakens the water retention capacity of the soil.In the early stage of crop growth and development,residual plastic film hinders soil water infiltration,resulting in the decrease of soil water content under the residual film and the accumulation of water content on the residual film.In the middle and late stage of crop growth and development,the existence of residual film hinders the upward migration of water under the film,resulting in the decrease of water content on the film and the water shortage in the surface soil.?2?The residual film had a significant effect on the growth and development of maize,but in different growth stages,the damage degree of residual film on the plant height,stem diameter and leaf area of maize varied.In the first 40 days after sowing,maize was significantly affected by the stress of residual film.The plant height,stem diameter and leaf area of maize were negatively correlated with the amount of residual film.The high growth rate of maize decreased with the increase of the amount of residual film,60d after sowing,compared with the treatment without residual film,the high growth rate of plants with residual film decreased the most,reaching 16.7%⁴2.3%.At the same time,affected by the residual film,the time for maize to enter the vigorous growth period and the end of the vigorous growth period was earlier than the control.When the amount of residual film exceeded a certain range(180 kg·hm^-2),the yield and related indexes of maize decreased significantly with the increase of the amount of residual film.?3?With the advance of the growth period of maize and the increase of the time of plastic film stress,the chlorophyll content of residual membrane treatment decreased more than that of the control group,and Compared with the control,the decrease of 60d after sowing was greater than 40d after sowing,and the decrease of 40d after sowing was greater than 20d after sowing.At the same time,due to the stress of residual film,malondialdehyde and proline in maize plants will gradually accumulate.The larger the residual film,the more free proline and malondialdehyde in corn leaves.The content of proline and malondialdehyde reached the maximum after sowing 20 days,The contents of proline and malondialdehyde treated with residual membranes were higher 25.84%¹39.72%and 43.49%¹53.65%than that of control T0 respectively.?4?The existence of residual film directly hindered the growth of maize roots.The residual film reduces the range of root water absorption and nutrients by reducing the root length density,root volume,root mass density and root surface area of maize were negatively correlated with the amount of residual film.At the same time,due to the effect of residual membrane obstruction,the dry weight of overground part and root dry weight of also decreased with the increase of residual membrane volume.This hindrance of residual film was more significant in the early stage of growth and development.Residual film also affected the spatial distribution of maize roots in the soil layer,so that the roots were more stranded in the residual film layer?0³0cm soil layer?.Compared with the control,the root weight ratio in the soil layer of 0³0cm increased by 4.14%on average,the root weight ratio in the soil layer of 30⁶0cm decreased by 18.87%on average,and the root weight ratio in the soil layer of 60⁹0cm treated with residual film decreased by 14.80%on average.