Degradation Characteristics Of Biodegradable Films In The Dry Land And The Impact Of Biodegradable Film Mulching On The Soil-corn System

Plastic film mulching technology is an important means to ensure food security in dry farming areas,but the problem of white pollution in farmland becomes more and more serious with the increase of plastic film mulching time,which has a serious negative impact on soil fertility and crop production.Biodegradable film has become one of the means to solve the pollution of farmland residual film.In order to clarify the impact of short-term coverage of biodegradable film on dry farmland,polyadipic acid/butylene terephthalate（PBAT）biodegradable film was used in this study.,and set up biodegradable white film（BWF）and biodegradable film.Five treatments of black film（BBF）,polyethylene white film（PWF）,polyethylene black film（PBF）and flat cropping without film（CK）were taken.method,to study the degradation of biodegradable film in dry farming area and the effect of short-term mulching on soil environment and crop growth.research shows:（1）During the field mulching process,the biodegradable albuginea entered the large cracking stage about 70 days after planting,and entered the crushing stage about 110 days after planting,and the mulching function was completely lost.The biodegradable black film entered the crushing stage about 110 days after the corn was planted.Before planting in the second year,the biodegradable film enters the film-free period.After the biodegradable film was covered in the field for 70 days,it was cut into mulch sheets of the same area,and then buried under 20 cm for 407 days,the remaining area of the biodegradable film was less than10%.Continue to corrode and lose mechanical properties.Infrared spectroscopy showed that the characteristic peaks of biodegradable films,such as the reduction of carbonyl intensity and peak area,and the formation of hydroxyl groups with respect to carbon-carbon double bonds.It shows that the biodegradable film has a good degradation effect on the surface and in the soil in the dry farming area.（2）Farming will lead to the decline in the total organic carbon content of the soil surface（0-20 cm）,After 3 years of planting,soil total organic carbon（SOC）content of each treatment showed a decreasing trend,and the PBF treatment is significantly decreased significantly after the planting in 2021 compared with the end of 2019（P<0.05）.After 3 years of experiments,there are no significant differences in the total organic carbon of the soil（0-20 cm）of the four different membranes.The coating increases the SOC content in large agglomerations（>2 mm）and small agglomerations（0.25-2 mm）to reduce SOC content in micro-dumplings（<0.25 mm）.The biodegradable membrane treatment significantly increases the SOC content in each particle size compared with polyethylene membrane treatment,and has a significant difference in the differences in large agglomerations（>2 mm）and small cluster（0.25-2 mm）（P>0.05）.Compared with the polyethylene film,the biodegradable membrane is conducive to the accumulation of SOC in the field surface.During the giving birth of the corn,the micro-environment formed by the biodegradable membrane and polyethylene film on the farmland leads to the difference in the use of the use of the voids of soil activated organic carbon components.Compared with polyethylene film,biodegradable film increased the ROC content of soil surface active organic carbon in the early growing season and leisure period of corn.After analysis,the content of soil surface DOC and ROC has significantly affecting the SOC content.The DOC has the most impact on the SOC and is a negative effect.ROC has positive effects on SOC.The same color biodegradable membrane treatment and polyethylene membrane treatment differences in the influence of soil DOC during the non-fertility period of the crop,while the biodegradable membrane treatment significantly increases the soil ROC content.It shows that the biodegradable membrane as a carbon source affects the surface microorganism of the soil,which is conducive to the accumulation of SOC.At the same time,the same color polyethylene film treatment soil CO₂flux is significantly higher than the biodegradable film（P<0.05）.The mineralization cumulative amount and mineralization rate of the same color biological decomposition film is higher than that of polyethylene membrane treatment,and the mineralization cumulative amount and mineralization rate of CK treatment are higher than that of the membrane treatment.Compared with polyethylene membranes,biodegradable membranes can be more mineralized at the surface of the soil,which reduces soil CO₂ flux,which is conducive to the solid support of SOC.（3）At different stages of maize growth,the soil moisture content and temperature of the lower surface layer（0-20 cm）treated with polyethylene film were higher than those treated with biodegradable film.The surface soil（0-20 cm）of each treatment room was collected after corn harvest.There was no significant difference in soil physical properties between biodegradable film treatment and polyethylene film treatment.The content of nitrate nitrogen in biodegradable film treatment was significantly higher than that in polyethylene film treatment（P>0.05）,and there was no significant difference in other soil chemical properties.The comprehensive index of soil fertility quality（IFI）of biodegradable film treatment was significantly higher than that of polyethylene film treatment and CK treatment（P>0.05）.The results showed that short-term coverage of biodegradable film in dryland agricultural area was helpful to improve the quality of soil fertility.（4）The agronomic characters and yield of Maize at different growth stages were measured.The results showed that there was no significant difference in agronomic indexes and yield between biodegradable film treatment and polyethylene film treatment,which were significantly higher than CK treatment,indicating that short-term coverage of biodegradable film in dryland agricultural area can replace polyethylene film to improve crop yield.（5）To sum up,considering the time scale of short-term film mulching（≤3 years）,it can be popularized to cover biodegradable film in maize cultivation system in agricultural areas of Loess Plateau.