福建省平和县琯溪蜜柚果园土壤磷环境风险评价研究

Risk assessment in soil phosphorus environment of Guanxi pummelo orchard in Pinghe County, Fujian Province

  • 摘要: 开展土壤磷环境风险评价对指导果园合理施肥和管理, 减轻果园面源污染具有重要意义。采用土壤室内培养法,?研究了平和县琯溪蜜柚果园土壤磷素环境敏感临界值, 并据此划分了果园磷环境风险等级。结果表明: 平和县琯溪蜜柚山地果园土壤磷素环境敏感临界值为96.3 mgkg1., 耕地果园为62.3 mgkg1; 提出平和县山地和耕地两类琯溪蜜柚果园土壤磷环境3级风险(高、中、低)划分标准; 根据风险划分标准对果园0~30 cm土层土壤和果园剖面(0~100 cm)土壤有效磷进行评价, 得出全县50.5%果园(48.4%山地果园, 52.7%耕地果园)处于磷素环境高风险状态, 12.2%果园(10.6%山地果园, 13.8%耕地果园)处于磷素环境中风险状态, 37.3%果园(41.0%山地果园, 33.4%耕地果园)处于磷素环境低风险状态; 供试42.1%果园剖面0~40 cm土层的磷环境处于高风险等级, 甚至部分果园0~100 cm土层土壤都有流失风险。为减少面源污染危害, 可对不同土壤磷环境风险状态琯溪蜜柚果园, 采用不同的磷肥施用策略; 过量施用磷肥易引起面源污染。

     

    Abstract: Risk assessment in soil phosphorus environment is important for rational fertilization and management of orchards, and reduce non-point source pollution of orchards. The aim of this study was to determine the sensitive critical value of soil phosphorus environments in Guanxi pummelo orchards in Pinghe County of Fujian Province. In the study, 030 cm soil layer was sampled both in mountain (red soil) and arable (paddy soil) pummelo orchards, and 0100 soil profiles were sampled in 19 towns of Pinhe County with different soil and water conservation measures. The laboratory soil culture method was used to determine soil phosphorus contents. And risk of soil phosphorus environment was classified according to Garden Soil Nutrient Abundant-Deficiency Index (Trial), and the sensitive critical value of soil phosphorus environment was determined by using correlation between soil available phosphorus and soluble phosphorus. The results showed that the sensitive critical value of soil phosphorus environment in Guanxi pummelo orchard in mountain regions was 96.3 mgkg1 and that in arable was 62.3 mgkg1. Base on phosphorus content, 3 grades of risk of soil phosphorus environments in Guanxi pummelo orchards were classified — high, medium and low. Based on the risk classification criteria, the available phosphorus contents in the 030 cm and 0100 cm soil layers in orchard fields were used to evaluate the risk of soil phosphorus environments. The evaluation results indicated that 50.5% of soil phosphorus environments in orchard fields were in high risk condition (48.4% mountain and 52.7% arable), 12.2% in medium risk condition (10.6% mountain and 13.8% arable) and then 37.3% in low risk condition (41.0% mountain and 33.4% arable). Some 42.1% of the orchard soil in the 040 cm soil layer was in high risk condition and even part of the 0100 cm soil layer was at risk of phosphorus loss. In order to reduce non-point source pollution risk, it is workable to adopt different phosphate fertilizer application strategies in different risk conditions in Guanxi pummelo orchards. It was recommended that in low risk orchard of phosphorus environments, farmers apply more phosphate fertilizer; while in medium risk phosphorus environments, farmers reduce phosphate fertilization dose; and then in high risk phosphorus environments, farmers stop phosphate fertilization. Excessive application of phosphate fertilizer caused non-point source pollution.

     

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