陕北中部丘陵区土壤肥力现状及提高土地生产力的途径

调查分析了延安宝塔区和安塞县7个乡镇近三年来的粮食生产，肥料投入以及各土地类型的土壤肥力状况，表明:投入的化肥中，氮肥以低浓度养分的碳铵为主，平均占肥料总量的38.3%，从施入土壤的N、P、K养分来看，K比例很小，结构不合理。土壤肥力总体水平低，且不同土地类型差异大；由于各乡镇自然和经济状况的差异，土地投入量不同，从而导致粮食产量相差悬殊，并且年际波动大。提高土地生产力的有效途径是培肥土壤和大力推广农作物高产栽培技术。

Situation of Soil Fertility and Approaches of Increasing Land Productivity in Loess Middle Hilly Region of Northern Shaanxi

The situation of grain production, fertilizer application and soil fertility in different land types at seven villages of Baota and Ansai counties in Yan’an district have been surveyed and analyzed.It showed that nitrogenous fertilizer to be used is mainly the ammonium carbonate, which contains lower concentration nutrients, and it amounts 38.3% in total used mineral fertilizers.Among the application nutrients of nitrogen, phosphate and potassium is the potassium nutrition very little, the proportion of used nutrients is not rational.The level of soil fertilities is low and difference of soil fertility is large in different land types.Due to natural and economic conditions in seven villages, the amount of applied fertilities are variant.So that, there are larger difference of grain yields and big waves in different years.The available ways of increasing land productivity are improvement of the soil fertility and extending techniques of cropping to high yield.