华北平原山药主产区土壤肥力和养分平衡现状及环境风险评价

Status of soil fertility, nutrient balance, and environmental risk assessment in yam production of North China Plain

以华北平原山药主产区为研究区域,通过实地调研、跟踪监测的方法,对山药田肥力现状和施肥现状进行分析,并利用农田养分输入输出模型解析山药田土壤养分平衡状况,同时对山药种植体系的环境风险进行综合评价。结果表明:1)山药田土壤有机质、全氮含量等级为极低水平,有效磷和有效锌含量为偏低水平,硝态氮、有效铜含量为中等水平,缓效钾、交换性钙、交换性镁、有效硫含量均达极高水平,速效钾、有效铁、有效锰含量则为高水平;2)山药全生育期氮(N)、磷(P2O5)、钾(K2O)养分投入量分别为575~943、341~981、655~1219 kg·hm-2,其中化肥氮(N)、磷(P2O5)、钾(K2O)投入占比分别高达83.0%、88.6%、91.3%,重无机轻有机以及养分投入过量和失衡问题突出;3)山药种植体系土壤氮、磷、钾盈余量分别达271.14、466.34、739.97 kg·hm-2,盈余率分别达48.7%、258.1%、324.5%,氮、磷、钾盈余量均超出环境安全阈值,分别属于中度风险、严重风险和严重风险等级。山药生产中化肥的投入对环境造成的风险总体上达到了重度风险等级。

Taking the main production area of yam in North China Plain as the research area, we analyzed the status of soil fertility and fertilizer application in yam production through field investigation and tracking monitoring, examined soil nutrient balance using the input-output model of nutrients in agricultural system, and assessed the environmental risks in the yam planting system. The results showed that: 1) the contents of soil organic matter and total N were extremely low, and the contents of available P and available Zn were both low;both nitrate and available Cu contents were at the middle level, the contents of soil slowly available K, available S, and exchangeable Ca and Mg were all extremely high, the contents of available K, available Fe, and available Mn were all at high level;2) The nitrogen(N), phosphorus(P2O5), and potassium(K2O) inputs were 575-943 kg·hm-2, 341-981 kg·hm-2, and 655-1219 kg·hm-2 during the whole growth period of yam, with chemical fertilizer accounting for 83.0%, 88.6%, and 91.3%, respectively;The input imbalance between organic and inorganic fertilizer, as well as the excessive nutrients input were prominent;3) The surplus rate of soil nitrogen, phosphorus and potassium reached 271.14 kg·hm-2, 466.34 kg·hm-2, and 739.97 kg·hm-2, with corresponding surplus ratio of 48.7%, 258.1%, and 324.5%, respectively, which all exceeded the environmental safety threshold and were classified as moderate risk, severe risk, and severe risk, respectively. The overall environmental risk caused by chemical fertilizer application in yam production had reached severe risk level.