GIS Study of Phosphorus Nutrient Input/Output in China at the County Level
基于GIS技术的中国农田磷素养分收支平衡研究

Using a nutrient balance farmland model and agricultural economic statistics, this paper analyzes the phosphorus balance of China's farmland at the national, provincial and county levels. Results show the following: 1) Total phosphorus nutrient input in China is 601×104t, and output is 328×104t, so the net surplus is 228×104t, or 0.029t/hm2 for farmland. The level of surplus P in farmland gradually declines from east to west; 2) 12.81% of counties, or 16.11% of China's cultivated area, have insufficient phosphorus, despite the huge surplus overall; 3) At the national level, chemical phosphate fertilizers and organic phosphate fertilizers account for 77.11% and 22.23% of total input amounts. Phosphorus from human and animal excreta accounts for 85.25% of total organic phosphate fertilizer inputs; 4) Biological phosphorus output from farmland amounts to 294×104t, accounting for 89.90% of total phosphorus output.