崇明东滩旱作农田土壤磷素流失及其影响因素

Loss of Soil Phosphorus From Rain-Fed Cropland and Its Affecting Factors in Dongtan of Chongming

  • 摘要: 对采用不同施肥和地表管理方式的梨园和菜地磷素的流失进行监测,研究了崇明东滩旱作农田土壤磷素的流失负荷、流失途径及其变化规律和影响因素,并分析了不同施肥和地表管理方式对农田土壤磷素流失的影响。结果表明,旱作农田土壤磷素径流流失、渗漏流失和泥沙流失浓度均超过水体富营养化总磷浓度临界值;土壤磷素流失以泥沙流失为主,泥沙总磷流失负荷占总磷流失总负荷的70.7%~82.2%;磷素流失主要发生在6、8和10月,这3个月总磷流失负荷占全年总磷流失总负荷的71.6%~73.0%。对磷素流失影响因素的相关分析表明,旱作农田土壤磷素流失与降雨量、降雨侵蚀力、径流量、径流水中总磷浓度等因素相关显著。与常规对照方式相比较,保持表土植被、覆盖地膜和精确滴灌,可减少旱作农田径流和泥沙产生量,降低总磷流失浓度,梨园和菜地总磷流失负荷消减率分别可达20.6%和12.6%。

     

    Abstract: Losses of soil phosphorus from pear orchards and vegetable gardens different in fertilization and field management in Dongtan of Chongming were monitored to study loads,pathways and temporal distribution of the losses from the rain-fed croplands and their affecting factors,and effects of fertilization and field management on the loss.It was found that the amount of phosphorus lost with runoff water,leaching water or sediment exceeded the critical concentration of waterbody eutrophication;Soil phosphorus loss occurred mainly with runoff sediment,which contributed 70.7%-82.2% to the total phosphorus loss.Phosphorus loss took place mainly in June,August and October,and the phosphorus loss in these three months accounted for 71.6%-73.0% of the total phosphorus loss in a year.Correlation analysis of affecting factors shows that the soil phosphorus loss from rain-fed croplands was highly related to precipitation,rainfall erosivity,runoff,phosphorus concentration in runoff,etc..Compared with the conventional fertilization and field managements,the practices of maintaining coverage of vegetation,using mulch films and running accurate drip irrigation could effectively decrease the yield of runoff and sediments and the phosphorus concentrations therein and hence the total soil phosphorus loss.In the pear orchard and vegetable field studied,the total phosphorus loss load decreased by as much as 20.6% and 12.6%,respectively.

     

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