聚乙烯降解产物对小麦生长中期土壤养分、水分和pH值的影响

目的:研究聚乙烯降解产物对小麦生长中期土壤养分、水分和pH值的影响,为以聚乙烯为原料的可降解地膜的推广提供依据.方法:用线型低密度聚乙烯(LLDPE),相对分子质量分别为5 000、3 000、2 000的聚乙烯粉末模拟聚乙烯降解产物,以0、7、35、70、140、350、700、1 050和1 400 g/m2土壤用量模拟聚乙烯残留量.盆栽试验,随机区组设计,6次重复.结果:各聚乙烯降解产物能提高土壤速效钾和水分含量;LLDPE降低土壤有机质含量,但增加碱解氮含量,其余降解产物具有相反作用;除相对分子质量为5 000的聚乙烯外,其余降解产物能提高有效磷含量.各聚乙烯残留量使土壤pH值明显降低,对土壤有机质、有效磷和水分含量多有增加作用;低残留量对碱解氮和速效钾含量有增加作用,高残留量对碱解氮和速效钾有降低作用.结论:不同聚乙烯降解产物对土壤有机质、有效磷、速效钾和水分含量多有增加作用,对碱解氮含量多有降低作用.增加聚乙烯残留量可提高土壤有机质、有效磷和水分含量,高残留量降低土壤碱解氮和速效钾含量.

Effects of Degradation Products of Polyethylene on the Nutrients,Moisture and pH of the Soil during Mid-Period of Wheat Growth

Objective Effects of degradation products of polyethylene on the nutrients,moisture and pH of the soil moisture and nutrients were studied to provide a basis for the development and promotion of the biodegradable mulching film with polyethylene as raw material.Methods Linear low density polyethylene(LLDPE),molecular weight of 5 000,3 000 and 2 000 polyethylene powder were used to simulate polyethylene degradation products;And nine degradation product dosages with 0,7,35,70,140,350,700,1 050 and 1 400 g/m2 soil were used to simulate polyethylene residues.Pot experiment was adopted with 6 repeats and randomized block design.Results All polyethylene degradation products can increase the soil moisture and available potassium contents.LLDPE can reduce the contents of soil organic matter and increase available nitrogen content,but the other degradation products have the opposite effects.Except 5 000 molecular weight polyethylene,the rest of degradation products can enhance the effective phosphorus content.The tested residual of polyethylene can obviously decrease pH value of soil,increase soil organic matter,effective phosphorus and moisture contents in most cases.Low amount of polyethylene residue have effects to increase available N and available K of soil,but high amount of polyethylene residue have effects to decrease available N and available K.Conclusion Different polyethylene degradation products can increase the organic matter,available P,available K and moisture content of soil and decrease available N content of soil during the mid-period of wheat growth in most cases.Increasing polyethylene residues can improve soil organic matter,available P,and moisture content,but higher polyethylene residue can reduce soil available N and available K.