紫云英配施氮肥对稻田生态系统服务功能的影响

紫云英是南方稻田重要的绿肥作物,翻压还田后可替代部分氮肥,减少化肥用量,提高农产品产量和品质。基于农田生态系统服务功能价值理论与方法,选取农产品供给、气体调节、土壤养分累积和水分涵养4类服务功能,对紫云英翻压配施不等量氮肥各处理下的稻田生态系统服务功能价值进行了评估。结果表明：紫云英还田后配施氮肥提高了稻田生态系统服务功能总价值。与冬闲处理相比,冬种紫云英处理下的农产品总产出增幅达7.56%~20.83%,气体调节功能价值增幅为21.64%~37.61%,水分涵养功能价值增幅为8.74%~26.26%,稻田生态系统服务功能总价值增幅15.15%~41.39%,尤其以紫云英与氮肥配施效果较好,其中紫云英+优化施氮处理在农产品供给总价值、产投比、气体调节功能价值、涵养水分价值等方面最高。该研究初步核算了紫云英配施不等量氮肥条件下的稻田生态系统服务功能总价值,有利于全面认识冬种紫云英的综合效益,为种植绿肥的生态补偿政策提供理论依据。

Effects of Combined Application of Chinese Milk Vetch (Astragalus sinicus L.) and Nitrogen Fertilizer on Ecological Service Function of Paddy Field

Chinese milk vetch (Astragalus sinicus L.) is an important green manure crop in paddy fields in South China. When returned to field, it can replace part of nitrogen fertilizer and reduce the amount of fertilizer, and improve the yield and quality of agricultural products. In this study, based on the agro-ecosystem service appraisal theory, we used methods in ecological economics to develop a systematic model to evaluate the ecological services value of paddy fields when combining Chinese milk vetch and nitrogen fertilizer in paddy fields in South China. This model considered the unique properties of green manuring, and the ecological services value were estimated by considering the influence of green manure on four ecological services functions including crop production, gas regulation, water conservation, and soil nutrient accumulation. Results showed: Chinese milk vetch with nitrogen increased the total value of paddy field ecosystem service function. Compared with the fallow treatment, the treatment with Chinese milk vetch increased 7.56%-20.83% of total output of agricultural products, 21.64%-37.61% of gas regulation function, 8.74%-26.26% of soil nutrient accumulation function, and 15.15%-41.39% of total value of ecosystem services. The effect is even better when combining Chinese milk vetch and fertilizer. Under the combined treatment with Chinese milk vetch and optimized nitrogen, total value of agricultural product supply, ratio of output to input, gas regulation value and conservation of water all reached the highest. This study preliminarily counted the total ecosystem service values of paddy fields under treatments with combining Chinese milk vetch and different amount of nitrogen. It had benefits to understanding of the comprehensive value of Chinese milk vetch, and the findings provided theoretical basis for decision making in planting green manure.