氮磷混合作种肥开沟集中施肥法(简称氮磷浅施),是防治小麦“小老苗”的一项有效的技术措施。“小老苗”起身、拔节、抽穗、成熟都较晚,而且植株矮、穗头小、粒子少,对小麦产量影响很大,亩产一般只有百斤左右。为此,我们廊坊地区农科所从1975年开始研究,认识到出现“小老苗”的主要原因是土壤肥力差,特别是表层土壤肥力太差,一 Nitrogen and phosphorus mixed for seed fertilizer ditching centralized fertilization (referred to as nitrogen and phosphorus shallow facilities), is to control wheat “small seedlings” is an effective technical measure. “Small seedlings” get up, jointing, heading, maturity are late, and the plant is short, small head, small particles, a great impact on wheat yield, generally only per kilogram per kilogram. To this end, we Langfang Agricultural Research Institute from 1975 began to study and recognize that the emergence of “small seedlings” is mainly due to poor soil fertility, especially the surface soil fertility is too poor, one