Effects of residual plastic film on crop yield and soil fertility in a dryland farming system

Plastic film mulch in agricultural production becomes essential to maintaining crop yields in arid and semiarid areas.However,the presence of residual film in farmland soil has also drawn much attention.In this study,three experiments were conducted.The first two experimental designs included 0,450,1350,and 2700 kg ha^(-1) of residual film pieces of approximately 5 cm side length added to field soil(0-20 cm soil depth)for seven years and added to pots for four years.In the third experiment,1350 kg ha^(-1)of the residual film with different side lengths(2-5,5-10,10-15,and 15-20 cm)was added to field soil for six years to explore the effect of residual film fragment size on soil nutrients,soil microorganisms,crop growth and yields.The residual film had little effect on the soil moisture at a field depth of 0-2(or 0-1.8)m.There were no significant effects on organic carbon,total nitrogen,inorganic nitrogen,total phosphorus or available phosphorus in the 0-20 cm soil layer.The presence of residual film decreased the richness and diversity of the bacterial community of the surface soil of the residual film,but it had no significant effect on the microbial community of the non-surface soil.The emergence rates of wheat and lentils occasionally decreased significantly with different amounts of residue fragments added to the field.At 450-2700 kg ha^(-1),the residual film reduced the plant height and stem diameter of maize and significantly reduced the shoot biomass of harvested maize by 11-19%.The average yields of maize and potato over the seven years decreased,but there were almost no significant statistical differences among the treatments.These results provide important data for a comprehensive scientific understanding of the effects of residual film on soil and crops in dryland farming systems.

Residual Film Pollution in the Eighth Division of the Xinjiang Production and Construction Corps

This study investigated the residual film content and distribution at different soil depths in the Eighth Division of the Xinjiang Production and Construction Corps.Before spring plowing in 2019,representative fields in four areas(Anjihai,Shihezi suburbs,Mosuowan and Xiayedi)were selected for residual film collection.The average content of residual film in the Eighth Division was 104 kg/ha.The residual film content in the four areas decreased in the order Anjihai>Shihezi suburbs>Mosuowan>Xiayedi.The average amount of residual film collected from cotton fields was greater than that from corn fields.Residual film content in the cotton field at soil depths of 0~10 and 10~30 cm was higher than that in the corn field,whereas the residual film content at a 30–50 cm soil depth in the corn field was higher than that in the cotton field.The results showed that farmers do not consider the long-term benefits,the high cost and short time of recycling,and the easy recycling of surface residual film.The shallow that the higher content of residual film,the less water in the soil of cotton.The same time,the results showed that the quantity of residual film in cotton field had greater influence on cotton quality.

Analysis and Control of Soil Residual Film Pollution Load in Cotton Fields in the Yellow River Delta

[Objectives]This study was conducted to explore the characteristics of soil residual film pollution load in cotton fields in the Yellow River Delta,so as to effectively control soil film pollution.[Methods]Cotton field mulching film survey and residue monitoring were conducted in the Yellow River Delta area.[Results]The amount of mulching film residues in cotton fields in the Yellow River Delta was 37.7-128.7 kg/hm^(2),which had a significant increase compared with 5 years ago,and the differences between plots were large;and after straw was returned to the field,the soil residual film obviously gathered in the 20-30 cm soil layer.The residual film blocks with a size of more than 25 cm^(2) accounted for 62.6%,which was a relatively high proportion,indicating that soil pollution can be caused easily,and it is difficult to control.During a certain period of time,the soil residual film pollution may have a tendency to aggravate,and the ecological risk is higher.[Conclusions]This study has important theoretical and practical significance for improving soil quality in the region and ensuring the safety of cotton field ecosystem and environmental health.

The status and distribution characteristics of residual mulching film in Xinjiang, China

Pollution of residual plastic film in arable lands is a severe problem in China. In this study, the status of residual film and influential factors were investigated using the methods of farm survey in combination with questionnaires and quadrat sampling at a large number of field sites in Xinjiang Uygur Autonomous Region, China. The results showed that the amount of film utilization increased largely and reached to 1.8×10~5 t in 2013. Similarly, the mulching area also substantially increased in recent decades, and reached to 2.7×10~5 ha in the same year. According to the current survey, 60.7% of the sites presented a greater mulch residue than the national film residue standard（75 kg ha^（–1））, and the maximum residual amount reached 502.2 kg ha^（–1） in Turpan, Xinjiang. The film thickness, the mulching time and the crop type all influenced mulch residue. The thickness of the film had significantly negative correlation with the amount of residual film（P0.05）, while the mulching years had significantly positive correlation with it（P0.05）. The total amount of residual film in Xinjiang was 3.43×105 t in 2011, which accounted for 15.3% of the cumulative dosage of mulching. Among all the crops, the cotton fields had the largest residual amount of mulch film（158.4 kg ha^（–1））, and also the largest contribution（2.6×10~5 tons） to the total amount of residual film in Xinjiang.

Analysis on Content and Distribution of Residual Film in Fields of Different Crops

Before spring ploughing in 2019,the representative fields of the 8^(th) Division were selected,and residual film at different depths of soil in three areas of the 8^(th) Division was collected. Through the analysis on the weight and amount of residual film at different depths of soil,it was found that the average content of residual film in the 8^(th) Division was 104 kg/hm^2. From high to low,the content sequence of residual film in the three areas was Anjihai area,Mosuowan area and Xiayedi area. The average amount of residual film collected from the cotton field in the three areas was greater than that from the corn field. In the three areas,the content of residual film in the cotton field at the depth of 0-10 and 11-30 cm was higher than that in the corn field,while the content of residual film at the depth of 31-50 cm in the corn field was higher than that in the cotton field.

Design and test of the arc-shaped nail-tooth roller residual film recovery machine from the sowing layer

Residual films on the sowing layer produced after mulching in Xinjiang farmland,harm the sowing quality and root growth of crops.In this study,a sowing layer residual film recovery machine based on a radial plate arc-shaped nail-tooth roller structure was designed.Meanwhile,the key device structures were designed and the main working parameters were analyzed.Then,taking the working depth,the forward speed of the machine and the rotation speed of the nail tooth roller as the test factors,and the film collection rate and film intertwining rate as the test indicators,the single factor tests and the Box-Behnken response surface tests were carried out to evaluate the performance of the sowing layer residual film recovery machine.Consequently,the results showed that the order of significant factors was the working depth,the forward speed of the machine,and the rotation speed of the nail tooth roller.Besides,the optimal working parameters were determined,which the working depth,the forward speed of the machine,and the rotation speed of the nail tooth roller were 100 mm,4.8 km/h,and 49.3 r/min,respectively.Moreover,the predicted value of the film collection rate was 69.20%.Finally,the verification test was taken with the optimal working parameter,and the results showed that the film collection rate was 66.84%,and the film intertwining rate was 1.39%.The relative error between the test value and the predicted value of the film collection rate was 3.40%.It indicated that the machine can perform the collection of sowing layer residual films.This study can provide a theoretical basis and reference for the design of new sowing layer residual film machines.

Simulation and test on the operation process of an intermittent filmpicking component on full-film mulched double ditches

In view of the problems in operation process of fixed rake-type residual recycling component,such as poor individual profiling effect in film picking,easy clogging of the compound of films,soil and corn stubbles,high power consumption in film picking,and strong disturbance to seedbed soil,in this study,an operation model of intermittent filmpicking on full-film mulched double ditches was proposed and an intermittent film picking component was designed.The DEMMBD coupled algorithm was adopted for numerical simulation on the operation process of the intermittent film-picking component on full-film mulched double ditches,and a comparative analysis was carried out on the seedbed disturbance effect and resistance variation characteristics in film-picking by fixed and intermittent film-picking components.By taking the forward speed in film-picking,cam arrangement angle of the film-picking component and rotating speed of the cam shaft as independent variables,film-picking rate as the response value,a mathematical model between test factors and the film-picking rate was established,to explore the influence order of the factors on film-picking rate,and the optimal working parameters of the intermittent film-picking component were obtained as follows:the forward speed in film-picking was 2 km/h,cam arrangement angle was 180°,rotating speed of the cam shaft was 120 r/min.Under the optimal parameter combination,the average film-picking rate of the simulation test was 96.1%.Field test showed that,the average film-picking rate of the intermittent film-picking component was 95.6%,and 0.5%higher than that of the simulation test.The working condition of the sample machine was basically consistent with the simulation process,and can accurately represent the operation mechanism of intermittent film-picking on full-film mulched double ditches,showing that the established discrete element simulation model and its parameters were accurate and reasonable.

Separation and mechanical properties of residual film and soil

In Xinjiang's perennial cotton(Gossypium hirsutum)-planting soil,the average residual amount of plastic film is as high as 265.3 kg/hm2,and the problem of pollution with residual plastic film in the tillage layer has become a major problem.To explore the mechanism of the separation of residual film and soil in the tillage layer and determine the conditions favorable for the separation of residual film-soil,this study established a constitutive model of residual film-soil contact based on the discrete element method and used the established constitutive model to simulate the process of separating residual film and soil.In addition,the influence of parameters,such as soil particle size and water content,on the force to separate the residual film and soil was studied using single factor and orthogonal experiments.The simulation results showed that the changing trend of the residual film-soil separation force curve did not differ much between the simulation and the actual comparison,and the curves were roughly the same.They all decreased after the separation force reached its peak value,but the simulated separation force curve was similar to that of the actual separation force.It increased rapidly from the beginning and reached peak separation force first.The single-factor experiment showed that the separation force of the used residual mulching film was higher than that of the unused mulching film.Under the same conditions,the maximum separation force required to separate the residual membrane was proportional to the positive pressure on the surface of the residual membrane and the size of soil particles.Under the same conditions,the maximum separation force required to separate the residual film is proportional to the positive pressure on the surface of the residual film and the size of soil particles.The maximum separation force decreased first and then increased as the soil moisture content increased.The results of the orthogonal experiment showed that the soil particle size had the greatest effect on the maximum separation force,followed by positive pressure on the residual film surface,soil moisture content,and the service life of mulch.In addition,film mulch that was buried 60 mm deep in the soil,a particle size of more than 2.5 mm,and a soil moisture content of 8%was the optimal combination of parameters to effectively separate the film mulching residue from the soil.

Impact of agricultural residual plastic film on the growth and yield of drip-irrigated cotton in arid region of Xinjiang, China

Long-term and widespread use of plastic mulching has led to the accumulation of residual plastic film(RPF)in farmland soils of Xinjiang,China.However,there is no specific quantitative basis for RPF pollution or a clear understanding of the influence of residual film on crop growth.The aim of this study was to investigate the effect of RPF on the growth of cotton,an important cash crop of Xinjiang.Based on the field conditions and previous reports,various amount of residual film was applied in 0-30 cm soil layer.The growth index including emergence rate,dry matter,and yield of cotton was examined at different growth stages under different soil residual film levels.Results demonstrated a significant effect of RPF on soil moisture distribution and movement.Plastic residues had a significant effect on cotton growth at levels above 200 kg/hm2,and the yield decreased as the RPF amount increased.Based on these findings,200 kg/hm2 was suggested as a threshold level to determine the effects of RPF on cotton.This study provided a basis to rate RPF pollution in farmland soils and help understand the impact of pollution on crop productivity.

Experiment and optimal design of a collection device for a residual plastic film baler

It is imperative to carry out research on residual plastic film collection technology to solve the serious problem of farmland pollution.The residual plastic film baler was designed as a package for film strip collection,cleaning and baling.The collection device is a core component of the baler.Response surface analysis was used in this study to optimize the structure and working parameters for improving the collection efficiency of residual film and the impurity of film package.The results show that the factors affecting the collection rate of residual film and the impurity of the film package are the speed ratio(k)between the trash removal roller and eccentric collection mechanism,the number(z)and the mounting angle(θ)of spring teeth in the same revolution plane.For the collection rate,the importance of the three factors are in the order,k>z>θ.Meanwhile,for the impurity,the importance of three factors are in the order,z>k>θ.When the speed ratio,the mounting angle and the number of spring teeth was set at 1.6°,45°,and 8°,respectively,the collection rate of residual film was 88.9%and the impurity of residual film package was 14.2%for the baler.

Quantitative prediction of residual wetting film generated in mobilizing a two-phase liquid in a capillary model

This research studies the motion of immiscible two-phase liquid flow in a capillary tube through a numerical approach employing the volume of fluid method,for simulating the core-annular flow and water flooding in oil reservoirs of porous media.More specifically,the simulations are a representation of water flooding at a pore scale.A capillary tube model is established with ANSYS Fluent and verified.The numerical results matches well with the existing data available in the literature.Penetration of a less viscous liquid in a liquid of higher viscosity and the development of a residual wetting film of the higher viscosity liquid are thoroughly investigated.The effects of Capillary number,Reynolds Number and Viscosity ratio on the residual wetting film are studied in detail,as the thickness is directly related to the residual oil left in the porous media after water flooding.It should be noticed that the liquids considered in this research can be any liquids of different viscosity not necessarily oil and water.The results of this study can be used as guidance in the field of water flooding.

Design and experiment of seed furrow cleaning device based on throwing and sliding for no-till maize seeding

In order to solve the serious problems of seeds are covered by residual film and overhead by straw during no-till seeding,a seed furrow cleaning device for no-till maize seeding was developed,which adopted a collaborative cleaning method of rotating spring teeth and curved sliding shovel.The movement process and motion trajectory of throwing residual film and straw were constructed.The maximum distance of throwing to one side in horizontal and maximum height in vertical were obtained.The motion trajectory of adjacent spring teeth was analyzed by Matlab,the motion trajectories of adjacent spring teeth at different speeds of 120 r/min,150 r/min and 180 r/min were achieved,the theoretical analysis results showed that the area of omitted area decreased with the increase of rotation speed.Based on theoretical and simulation analysis of critical parameters,the forward speed of machine,rotation speed of spring teeth,and dip angle between spring teeth and rotary disc were selected as the influencing factor.Straw cleaning rate(SCR)and residual film cleaning rate(RFCR)were selected as the response values for three factors and three levels of orthogonal experiment design.The optimal combination of the selected parameters was obtained,and the field test verification was also conducted.The results showed that the rotation speed of spring teeth,forward speed and dip angle of spring teeth significantly affect SCR and RFCR were in decreasing order.The field test results indicated that when forward speed was 6 km/h,rotation speed of spring teeth was 180 r/min and dip angle of spring teeth was 40°,SCR and RFCR were 88.27%and 84.31%,respectively.This study provides a reference for the development of no-till seeder in Xinjiang and the northwestern regions of China.