水土保持措施降低河网平原区果园地表氮磷铜流失

    Application of different management measures to reduce runoff losses of nitrogen, phosphorus and copper from orchard in dense river network plain

    • 摘要: 河网平原因地下水位高、内排水较差,进行水果生产需要深沟排水以便适合果树根系的生长,但这些直接与水体连接的排水沟也大大促进了果园氮、磷等养分的流失。为了解不同水土保持措施对水网平原果园地表养分流失的影响,本文采用天然降雨条件下的小区试验研究了生物措施(种植黑麦草)、化学措施(表施沸石+石灰石粉)和工程措施(在排水沟内设置沉砂坑)对水网平原果园地表径流氮、磷、铜流失的影响。结果表明,生物措施能减少18.6%的径流水量流失;生物措施、化学措施和工程措施能分别减少52.6%、16.3%和38.3%的泥沙流失。地表泥沙携带侵蚀是果园氮、磷、铜流失的主要途径,生物措施能使总氮流失减少23.6%;生物措施、化学措施和工程措施能使总磷流失分别减少38.66%、18.53%和22.68%,总铜流失分别减少41.4%、18.4%和29.9%。三种水土保持措施对降低磷、铜流失的效果好于降低氮流失的效果。同时采用生物措施、化学措施和工程措施可使氮、磷、铜流失量明显降低,有助于果园周围水体环境的保护。

       

      Abstract: Abstract: Nitrogen and phosphorus losses from agricultural fields have become more common in China in last two to three decades as a result of increase of fertilizer application. Nonpoint-source pollutants of agricultural production play an important role in eutrophication of lakes and rivers. Thus, controlling the transport of pollutants in runoff is critical to reduce freshwater eutrophication. Dense river network plain region is an intensively managed agricultural production area where concerns over nutrients and heavy metals have been raised. Fruit production within this region is unique in that it often occurs on beds due to the high water table level in this historically wetland area. Beds is designed to support a single row of trees along the top, and large volumes of surface runoff and associated agrichemicals such as nitrogen, phosphorus and copper may leave the production areas in a short period of time due to these drainage features. To investigate the effects of agricultural management measures on runoff losses of nutrients from orchard in the region, in this paper, a plot observation experiment under the conditions of natural rainfall was carried out to study the effects of different measures on runoff losses of nitrogen, phosphorus and copper from orchard in the region. The experiment included five treatments, i.e. control without application of any measures, biological measure with plantation of ryegrass, chemical improvement measure with application of mixture of zeolite and lime powder, engineering measure in that sand sedimentation pit is arranged in the drainage ditch, and comprehensive measures with combined application of biological, engineering and chemical measures. The annual application rates of N, P, K were 1150, 150, and 125 kg/hm2, respectively. Losses of sediment, total and dissolved P, N, and Cu in surface runoff for each of the experimental plots were monitored between January of 2009 and December of 2010. The result showed that application of biological measure reduced runoff volume by 18.6%, and application of biological measure, chemical improvement measure and engineering measure reduced sediment by 52.6%, 16.3% and 38.3%, respectively. Runoff and sediment surface erosion is the main way to carry the nitrogen, phosphorus, copper loss. After biological measure, chemical improvement measure and engineering measure were implemented, the total phosphorus loss is reduced by 38.66%, 18.53%, and 22.68%, and the total copper loss is reduced by 41.4%, 18.4% and 29.9%, respectively. Application of biological measure reduced total nitrogen loss by 23.6%. Reduction effects of phosphorus, copper loss by application of the three measures were greater than that of nitrogen loss. Combined applications of biological, chemical and engineering measures can make the nitrogen, phosphorus, copper loss decrease significantly, which contribute to the protection of water environment around the orchard. These results indicate that all of the biological, chemical and engineering measures are effective management practices that reduce P, N, and Cu runoff from orchard in dense river network plain.

       

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