施用长效尿素应做到“四宜、四忌”胡传旭１．四宜一宜施在瘠薄土壤中种植的作物Ｌ，增产效果显著，经济效益高。二宜施于木本作物和生长期较长的作物上，以免氮素当季利用率低，增产效果不高。三宜作基肥，以便可较长时间地发挥肥力。如要用作追肥，要早期施用，且深施于... Long-term use of urea should be “four should be four bogey” Hu Chuanxu 1. Four should be a suitable application in barren soil planting crops L, a significant yield increase, high economic efficiency. Two should be applied to the woody crops and longer growing crops, so as to avoid the seasonal utilization of nitrogen is low, the yield is not high. Three should be based on the base, so that a longer time to play fertility. To be used as top dressing, to be applied early, and deeply applied to ...