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.

Distribution of microplastics in mulched soil in Xinjiang, China

In order to study the distribution of soil microplastics in the plastic film mulched farmland,the fluidization-centrifugation secondary density flotation method was optimized and improved to obtain the samples.The main components of microplastics were analyzed by Fourier spectrometer,and the surface morphology,porosity,particle size and abundance distribution characteristics of microplastics were studied by electron microscopy.The results showed that plastic mulch is the main source of microplastics.Its morphology mainly consists of fragments,fibers and particles.The size of debris microplastics was larger,with an average of 1.6300 mm,mainly distributed in the 0-300 mm cultivation layer while the size of particle micro plastic was smaller,with an average of 0.1400 mm.The width of fiber microplastic was 5-20μm,but the length could reach 0.2000-2.0000 mm,with an average particle size of 0.9200 mm.Fiber and granular microplastics could be seen in each soil layer.The surface layer of microplastics has a large number of pores characterized with a length of 50μm and a width of about 5-10μm,which might be an easy oxidation site for microplastics.This oxidation is continuous,making microplastics continuously decompose into smaller particles.The abundance of microplastics is negatively correlated with soil depth.The average abundance of microplastics is 161.50±5.20 pieces/100 g in 0-300 mm soil layer,which is their main enrichment area.However,the average abundance of microplastics decreases to 11.20±1.10 pieces/100 g in 400-800 mm soil depth.Moreover,the average particle size of microplastics is also linearly negatively correlated with soil depth.Microplastics with smaller particle size are easier to migrate as they pass through soil pores under the action of water and fertilizer.The research can provide s reference for understanding plastic mulch pollution.

Novel technique of controlled laser air-force detection for rheological properties of polymers

A novel controlled laser air-force detection(CLAFD)technique was developed to detect the rheological properties of polymers with the characteristics of non-destruction and cross-contamination free.Dynamic testing and static testing were carried out in the technique.Back propagation neural network algorithm was used to establish the air-force control model.The replicability of CLAFD system was analyzed,the viscoelastic properties of polyurethane were investigated using alternating load testing.A comparative analysis of performances was made between the CLAFD and the texture analysis(TA)on the testing of creep-recovery and stress relaxation.The results demonstrated that the CLAFD system had good replicability.The lagging phase angle was between 0°-90°in the testing of alternating load.This illustrated that the CLAFD technique could be used to detect viscoelasticity.The parameters of response speed and the precision of the CLAFD entirely surpassed the TA on the creep-recovery testing.The CLAFD technique will provide a new real-time,non-destruction and cross-contamination-free detection method for material science,especially for those materials such as artificial biological tissue and function food products.