5种源汇型农作景观组合控制农田养分流失的试验研究

【目的】验证不同源汇型农作景观组合对削减农田泥砂、氮、磷排放的效果。【方法】于2014—2017年在浙江省选择蔬菜地-茭白田、蔬菜地-水田、果园-茭白田、桑园-水田和果园-荷塘等5种南方地区有代表性源汇型农作景观组合模式,进行定位观察,比较分析了其对泥砂量、总磷量、可溶性磷量、总氮量和可溶性氮量的减排效果。【结果】与"汇"处理前的"源"农田比较,5种源汇型农作景观组合农田泥砂和养分流失削减比例均在70%以上,平均削减率总磷量(90.63%)>可溶性磷量(89.14%)>泥砂量(88.72%)>可溶性氮量(86.75%)>总氮量(86.64%)。5种景观组合对削减排水中泥砂量、总磷量、可溶性磷量、总氮量、可溶性氮量的效果表现为果园-荷塘>蔬菜地-茭白田>果园-茭白田>桑园-水田>蔬菜地-水田。【结论】源汇型景观组合对污染物的削减主要通过减少排水与对污染物吸收、吸持来实现,是一种方便、低廉、高效的农田系统养分流失控制技术;并以"汇"为荷塘或茭白的组合模式效果为佳。

Comparison of Different Intercropping Systems for Reducing Nutrients Loss from Farmland

【Objective】Nutrient loss from agricultural soils is a great environmental concern in many countries, and rotating crops and intercropping are believed to be one solution to slowing down this loss. The aim of this paper is to investigate the efficacy of different intercropping systems in reducing the loss of suspended solids and major dissolved nutrients from farmland.【Method】 The experiment was conducted from 2014 to 2017 in Zhejiang province, southeast China. We compared five intercropping systems: vegetable-Zizania latifolia, vegetable-paddy rice, orchard-Zizania latifolia, mulberry-paddy rice and orchard-lotus pond, with traditional cultivation used by local farmers taken as the control. In each system, we measured the reduction in sediment loss, change in total and soluble phosphorus(P), total and soluble nitrogen(N).【Result】Compared with the control, all five intercropping systems reduced the loss of suspended solid and P and N by more than 70% on average. In particular, they reduced the total P loss by 90.63%, soluble P loss by 89.14%, suspended solid loss by 88.72%, soluble N loss by 86.75%,and total N loss by 86.64%. In terms of efficacy, the five systems were ranked in the order of orchard-lotus pond >vegetable-Zizania latifolia > orchard-Zizania latifolia > mulberry-paddy rice > vegetable-paddy rice.【Conclusion】The mechanisms underlying the intercropping systems for reducing loss of suspended solids and nutrients from soils was the reduced drainage and the increased ability of soil to absorb nutrients. Intercropping is a low-cost but efficient technology to ameliorate nutrient loss from farmland systems. For the five intercropping systems we compare, lotus pond-Zizania latifolia was most effective.