• 关键词：氮平衡  磷平衡  表观平衡  农田  高原山地

• 基金项目：国家自然科学基金（No.41701631）；云南省基础研究计划青年项目（No.Y0120160068）

• 李金城
• 云南大学生态学与环境学院, 昆明 650091

• 杜展鹏
• 云南大学生态学与环境学院, 昆明 650091

• 严长安
• 昆明市环境科学研究院, 昆明 650032

• 高伟
• 云南大学生态学与环境学院, 昆明 650091

• 摘要：氮、磷平衡是影响农田污染潜势和农业生产的主要因子.农田化肥过量施用导致的氮、磷大量流失已成为我国非点源污染的重要来源.本研究基于农田氮、磷表观平衡模型，以高原山地城市昆明市为例，评估了1980-2015年农田的氮、磷输入、输出与平衡演变特征.结果表明：①1980-2015年，昆明市农田氮平衡始终处于盈余的状态，盈余量以4070 t·a^-1的速度上升，而农田磷从1981年开始转变为盈余状态，盈余量以590 t·a^-1的速度上升，农田氮盈余量增长速度高于磷盈余量增长速度，未来农田氮污染潜势可能高于磷；②化肥和有机肥是昆明市农田氮、磷输入的主要来源，自1995年化肥取代有机肥成为氮输入的主要来源，自1983年起化肥成为农田磷的最大输入项；③氮、磷输出量均呈现逐年增长趋势，其中，氮输出量增长速度为3430 t·a^-1，磷输出量增长速度为100 t·a^-1，农田氮、磷输出量远低于输入量；④昆明市农田氮、磷平衡特征在不同海拔区域呈现显著异质性，1980-2015年海拔2400 m以下的农田氮、磷表观平衡情况变化最为明显，平均增长了12.48倍，2400 m农田变化次之，2400 m以下农田变化较小.

• Abstract：Nitrogen and phosphorus balances are key factors affecting the pollution potential of cropland and agricultural production. The loss of nitrogen and phosphorus caused by over-application of fertilizers has become an important driver for nonpoint source pollution in China. Current and historical change of nitrogen and phosphorus inputs, exports, and balances in the cropland of Kunming were estimated from 1980 to 2015 with cropland nutrients apparent balance model. Results showed that:①From 1980 to 2015, the nitrogen balance of cropland had been surplus with a rate of 4070 t·a^-1. In 1980, the phosphorus balance of cropland was in a deficit state, and had been turned into a surplus state since 1981 with an increase of 590 t·a^-1. The growth rate of nitrogen surplus is higher than that of phosphorus surplus, indicating a higher pollution potential of nitrogen than phosphorus in the future. ②Fertilizer and organic manure are the main sources of nitrogen and phosphorus inputs. Since 1995, fertilizers replaced organic manure as the main source of nitrogen input, while chemical fertilizers have become the largest input of phosphorus since 1983. ③Nitrogen and phosphorus outputs have been increasing year by year. The output growth rates of nitrogen and phosphorus are 3430 t·a^-1 and 100 t·a^-1, respectively. Compared to the input rates of nutrients, output rates are much lower. ④Based on the land-use conversion of Kunming from 1980 to 2015, the apparent balance of nitrogen and phosphorus in cropland below the altitude of 2400 m increased the most by 12.48 times, followed by cropland at 2400 m, and the cropland below 2400 m changes the least.

• Key words：nitrogen balance  phosphorus balance  apparent balance  cropland  plateau highland

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