一、“三合肥”的增产效果渭北山区和旱原的许多薄地施肥很少,有的甚至长期不施肥,土地瘠薄,缺乏氮、磷、有机质及某些微量元素。这不但直接影响到作物对养分的需求,而且由于苗弱根少,吸收水分面积小,特别是干旱来临时,根系不能及时伸展到土壤深层吸收利用水分,加之土壤瘠薄,缺乏有机质,保水力差,因而削弱了作物的抗旱能力。所以,地薄的问题就成为渭北山旱地限制小麦增产的主要因素,提高地力就成为山旱地小麦增产措施的主攻方向。为了解决生产上这个重大问题,1971年以来,我们在麟游县山区洪三大队进行了多年的研究,结果 First, the “three Hefei,” the effect of increased production Weibei Mountain and dry land of many thin-field fertilization, and some even without long-term fertilization, barren land, the lack of nitrogen, phosphorus, organic matter and some trace elements. This not only has a direct impact on crop nutrient demand, but also due to less seedlings and less water absorption area, especially when the drought comes, the root system can not be extended to deep soil moisture absorption and utilization, combined with soil infertility, lack of organic matter, poor water retention , Thus weakening the drought resistance of crops. Therefore, the issue of the thin ground has become the main factor limiting the wheat yield increase in the Weibei Mountain upland. Increasing the soil fertility has become the main direction of increasing the yield of wheat in the mountain dry land. In order to solve this major issue of production, since 1971, we conducted years of research in the Hongsan Brigade in the mountainous area of ​​Linyou County. As a result,