北京市房山区农田表观磷平衡分析

农田土壤养分的积累使潜在农业非点源污染负荷增加,为对农田磷素优化管理、水环境质量改善及环境政策制定提供科学依据,通过OECD土壤表观磷素平衡模型,以2001、2003、2005和2007年北京市房山区农田的磷素平衡核算框架和数据库为基础,结合GIS技术对该区域磷素平衡强度进行了分析.结果表明,化肥是房山区农田养分中磷素投入最重要的来源,化肥平均磷投入量随着时间的增加而增大,从2001年的111.34 kg·hm~(-2)增加到2007年的407.42 kg·hm~(-2),局部地区已远超过华北地区和全国平均水平.房山地区农田磷素输入总量和土壤表观磷平衡总量在2001-2007年表现为先降低后增加,而磷的输出量一直呈下降趋势;平均磷素投入量和平衡强度以较大速率逐年递增.区域表观磷素平衡量具有明显的空间变异特征,2001-2007年房山地区农田磷素盈余趋势表现为南高北低,中部和南部的磷素平衡强度一直在持续增加,特别是东南部和西南部地区增加速度较快.磷素平衡的驱动力的变化是造成磷素平衡空间差异得直接原因,总体表现为种植业驱动型盈余>双驱动型盈余>养殖业驱动型盈余.

Analysis of surface phosphorus balance of farmland in Fangshan district, Beijing

A framework and database of phosphorus production in 2001, 2003, 2005, and 2007 in the District of Fangshan, Beijing was developed in this study. It was established based on the OECD surface soil phosphorus balance model. The regional phosphorus balance intensity was analyzed with applying GIS. The results indicated that fertilizer was the most important source of phosphorus input in farmland, and the average phosphorus fertilizer input kept increasing. It has been increased from 111.34 kg·hm~(-2) in 2001 to 407.42 kg·hm~(-2).in 2007, and some areas have exceeded average level of North China and National standard. The total farmland phosphorus and surface soil phosphorus balance were decreased at the beginning and then increased, while phosphorus output declined from 2001 to 2007. The average phosphorus input and balance intensity have been increased significantly every year. The surface balance of phosphorus in the region has various spatial differences. The phosphorus surplus trend in the south of farm-land was higher than in the north; the balance intensity in the central and southern part kept increasing, especially southeast and southwest. The changes of phosphorus balance driving force were the direct reason of spatial differences, as a whole, planting driven surplus > double driven surplus > breeding driven surplus. The accumulation of soil nutrient in farmland would contribute to the increase of potential loads of non-point source pollution. This paper provided scientific basis for phosphorus optimal management of farmland、 water quality improvement and environmental decision making.