灌溉方式对保护地土壤磷素淋失风险的影响

自连续12年以相同试验方案、不同灌溉方式进行灌溉试验的保护地采集土壤样品,对不同灌溉处理土壤磷素淋失风险进行评价,并对影响土壤磷素淋失临界值大小的因素进行了探讨。灌溉处理设滴灌、沟灌和渗灌三种灌溉方式,采样深度为0~80 cm。结果表明,0~20 cm沟灌、渗灌和滴灌处理土壤的磷素淋失临界值Olsen-P含量分别为59.44 mg kg-1、65.39 mg kg-1和68.57 mg kg-1;而20~40 cm层次的土壤淋失值分别为60.61 mg kg-1,66.8 mg kg-1和70.58 mg kg-1;40~80cm土层则无临界值存在。影响土壤磷素淋失临界值Olsen-P含量的主要因素有土壤pH和有机质、活性Fe、活性Al、有效磷含量;土壤pH值越大、有机质、活性铁、活性铝和Olsen-P含量越高,磷素淋失临界值越大。对三种灌溉处理表层土壤磷素淋失风险进行综合评价,其风险大小顺序为沟灌、渗灌和滴灌,这提示人们在保护地生产中要充分注意土壤磷素有效性,通过选择合理的灌溉方式、改善施肥技术以加强保护地土壤水肥管理,保证作物生产高效、优质和降低环境风险。

Effect of Irrigation Methods on Risk of Phosphorus Leaching Loss in Protected Field

Soil samples are collected from the protected field within 0-80 cm where the same block being tested in same test program but in different irrigation methods for 12 years,and the assessment index of phosphorus leaching risk is firstly established through the relationship of Olsen-P and CaCl2-P and then used to evaluate the surface soils of three irrigation methods.The modes of irrigation are subsurface irrigation,drip irrigation and furrow irrigation.The Olsen-P change points of drip irrigation,furrow irrigation and subsurface irrigation are separately 59.4 mg kg-1,65.39 mg kg-1 and 68.6 mg kg-1 in 0-20 cm,and 60.61 mg kg-1,66.8 mg kg-1 and 70.58 mg kg-1 in 20-40 cm,but there is no Olsen-P change points under different irrigation methods within 40-80 cm.All of soil samples for Olsen-P content of phosphorus leaching are significantly in excess of the change points.The important factors affecting particulate P loss is pH,the contents of organic matter,active Fe,active Al and available P of the soil.Evaluation of the risk under the three irrigation methods shows that the risk of different irrigations declined as drip irrigation>furrow irrigation>subsurface irrigation>drip irrigation,which suggests it is necessary to fully pay attention to the effectiveness of soil phosphorus by selecting a reasonable irrigation,fertilization techniques to strengthen the protection of soil water and fertilizer management,crop production to ensure efficient,quality and reduce environmental risks.