【摘要】 <正> 黄河上中游地区是我国北方主要的旱农区,又是我国著名的低产缺粮区。水土流失面积占80％,其中严重流失区占一半以上。干旱、水土流失,垒叠加剧,给生产生活带来很大困难。 本区在治理方针上曾有过工程措施与生物措施之争,各有见长。但不免都有单纯保持水土观点之更多还原

【Abstract】 Soil condition on the upper and middle reaches of the Yellow River is characterized by low content of carbonates, nitrates and phosphates as well as disproportion of nitrogen and phosphorous constituents, and thin layer of topsoil not being able to effect self-adjustment. These are the basic causes for droughts, severe loss of soil and water, inadequate functioning of conservation measures and, consequently, low grain output. The improvement of soil conditions is the only way of overall development of agriculture, forestry, animal husbandry and sideline occupations,for the establishing of rational and highly-efficient ecological system, which calls for immediate action.In order to improve the soil conditions, we should. ( 1 ) Increase the fertility through application of compound needed. ( 2 ) Carry on basic reconstruction of farmland. ( 3 ) Popularize drought-resisting methods of farming, appropriate to local conditions. (4) Include soil improvement and fertilizing in the work of remaking small watersbeds.The standards for basic farmland are. ( 1 ) For the case of terraces well-levelled land, essentially no erosion of soil, solid borders, water from a rainfall of 100 mm altogether held in the land without runoff, layer of manure soil not under 20 cm in thickness, content of organic compounds exceeding 1 %, total nitrogen content exceeding 0.7 %, effective phosphorous over 10 ppm, effective zinc content over 0.5 ppm,and per mu yield over 400 jin.Cultivated land behind silt trap dams: well-levelled land, essentially no soil erosion, sound structure of dam, land to hold 100 mm of precipitation during a rainfall, provision of proper drainage, layer of manure soil at least 22 cm thick, content of organic compounds exceeding 1.2 %, total nitrogen content over 0.08 %, effective phosphorous exceeding 14 ppm, effective zinc over 0.5 ppm, per mu grain output over 500 jin.更多还原