Impact Of Polyethylene Film Residues On Crop Yields,Soil Quality And Soil Microbial Community Composition

Following fertilizer,irrigation,and pesticides,mulching has become the most important agricultural measures to increase crop production.However,there are much plastic film residues in soil which may cause pollution.In order to investigate the effect of plastic film residues on crop yield and soil quality,we conducted a pilot field experiment in two locations-the Yuzhong Experiment Station of Lanzhou University and the Semiarid Ecosystem Research Station North Mountain of Yuzhong County in 2012 and 2013.Maize and potatoes were planted in each location and crop rotation method was applied.There were eight treatments including two locations,two crops,and two years.Film residues was collected and shredded with an area less than 25cm²,then incorporated into the field.Crops were then planted.There were four levels of film residue input:F0(0 kg ha^-1),F10(450 kg ha^-1),F30(1350 kg ha^-1),F60(2700 kg ha^-1),represented ten,thirty,and sixty years of plastic film resides in the field,respectively.In 2012 and 2013,a pot experiment was also conducted in a rainout shelter at the Yuzhong Experiment Station of Lanzhou University.Soybean was planted in 2012,and wheat was planted in 2013.The treatment was similar to those of field experiment.The preliminary results from field experiment showed that film residues had no significant influence on the yield and water use efficiency of maize and potato in contrast with the treatment without film incorporation.The results from both field experiment and pot experiment showed that film residues also had no effect on soil organic carbon,soil nutrients and microbial biomass.So we could concluded that there were no negative effect of plastic film residues on crop productivity and soil property in a short time.Plastic film residues increased soil microbial community diversity.In field experiment,there were twenty types of bacterium extracted from the surface soil of film residue compared to nineteen types from the control.In pot experiment,there were twenty-nine types of bacterium extracted from the surface soil of film residue compared to twenty-five types from the control.According to the results from DGGE analysis,the impact of plastic film residues on soil microbial community’s structure increased with the amount of plastic film residues.The impact of plastic film residues on soil microbial community diversity related to whether there was a plant grown in the soil.There were more effects of plastic film residues on soil microbial community’s structure in the field with crop planted than in fallow field without crop planted.In the present study,we found the plastic film residue with an area less than 25cm² had no adverse effect on soil property and crop production.In some treatments,plastic film residues were even benefit for crop growth.These results provided a method to solve the problem of plastic film residues.Plastic film residues may not be taken as pollution,which may even be changed from a hazard to a benefit.That is important to reveal the relationship of plastic film residues and soil quality and productivity.It will be possible to eliminate the worries of plastic film resides,and provide a scientific basis for the protection of food security and ecological safety in arid and semiarid areas.