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研究了陕西省及典型农区农田生态系统中养分平衡的结果表明 ,1977年氮磷处于亏缺状态 ,80年代末达到平衡且略有盈余 ,到 1997年盈余较多 ,钾则一直赤字。 1997年 N∶ P2 O5 ∶ K2 O为 1∶ 0 .2 6∶ 0 .0 8,低于发达国家水平 (1∶ 0 .42∶ 0 .42 )。预计到 2 0 0 7～ 2 0 12年全省农田年化肥需求量为 :氮肥 (N) 870 0 0 0 t,磷肥 (P2 O5 )36 5 0 0 0 t,钾肥 (K2 O) 1740 0 0 t。适宜的 N,P2 O5 ,K2 O养分比为 1∶ 0 .40～ 0 .42∶ 0 .15～ 0 .2 0。
The results of the study on the nutrient balance of farmland ecosystem in Shaanxi Province and typical agricultural areas show that nitrogen and phosphorus were in deficit in 1977 and reached a balance with a slight surplus in the late 1980s with more surplus in 1997 and a deficit in potassium. 1997 N: P2 O5: K2 O is 1: 0.26: 0.80, lower than the developed country level (1: 0.42: 0.42). It is estimated that the annual demand of fertilizer for farmland in the whole province from 2007 to 2012 is: 870 0 0 t of nitrogen fertilizer, 36 5 0 0 t of phosphorus fertilizer, K2 0 1740 0 0 of potassium fertilizer, t. Appropriate N, P2 O5, K2 O nutrient ratio of 1: 0 .40 ~ 0 .42: 0 .15 ~ 0.