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本研究利用OECD土壤表观氮素平衡模型,通过建立1991—2004年北京市通州区农田的氮素平衡核算的框架和数据库,结合GIS技术对该区域氮素平衡强度及特征进行了分析,通过农户调查通州区典型种植模式和典型作物的肥料投入情况。结果表明:通州区农田氮素输入总量从1991年的4万t降低到了2004年的1.7万t,平均氮素输入量从567.86 kg/hm2增加到了585.22 kg/hm2,氮素平衡强度从1991年的355.84 kg/hm2增加到了2004年的389.39 kg/hm2。将氮素平衡强度划分为5级,结合空间分布特征分析发现,通州区下属各乡镇的农田氮素平衡量普遍提高,其中近半数氮素平衡强度从1991年的Ⅰ、Ⅱ级上升到了2004年的Ⅳ、Ⅴ级。城郊地区氮素平衡强度变化正与城郊农业种养结构调整密切相关,蔬菜作物播种面积的增加和养殖业的发展使农田氮素输入量持续增加,氮素平衡量提升明显,空间变异加大,对农田污染潜在威胁提高。农户调查表明,粮食作物的肥料施用量是比较合理的,而蔬菜作物的施肥量过大。
In this study, using the OECD model of soil apparent nitrogen balance, we established the framework and database of nitrogen balance accounting of farmland in Tongzhou District of Beijing from 1991 to 2004, and analyzed the nitrogen balance intensity and characteristics in this area through GIS technology. Farmers survey Tongzhou typical planting patterns and typical crops of fertilizer inputs. The results showed that the total input of farmland nitrogen in Tongzhou District decreased from 40,000 t in 1991 to 17,000 t in 2004, and the average nitrogen input increased from 567.86 kg / hm2 to 585.22 kg / hm2. The nitrogen balance intensity increased from 1991 to 1991 The 355.84 kg / hm2 of the year increased to 389.39 kg / hm2 in 2004. According to the analysis of spatial distribution characteristics, the nitrogen balance of farmland in each township under Tongzhou District generally increased, of which nearly half of the nitrogen balance intensity rose from Ⅰ and Ⅱ in 1991 to 2004 Of Ⅳ, Ⅴ level. The change of nitrogen balance intensity in suburban areas is closely related to the adjustment of agricultural planting and planting structure in suburbs. The increase of sown area of vegetable crops and the development of aquaculture led to the continuous increase of input of nitrogen in farmland, obvious increase of nitrogen balance, increase of spatial variability, Potential threats to farmland pollution are raised. Household survey shows that the amount of fertilizer applied to food crops is more reasonable, while the amount of fertilizer applied to vegetable crops is too large.