不同牧草对黄土丘陵区土壤培肥效果的研究

以黄土丘陵区具有代表性的禾本科笔草无芒雀麦及豆科牧草沙打旺，草木樨为材料，研究其对川台地土壤腐殖质含量和组成，有关营养元素及后茬作物产量的不同影响，结果表明，种植禾本科及豆科牧草均能提高土壤中腐殖质及氮素营养的水平，其中禾本科牧草效果较豆科牧草更为明显，它们对土壤中微量元素的影响因各自对营养元素的利用程度而异。三种牧草样地后茬作物的产量以草木樨为高，无芒雀麦不宜与禾本科作物轮作。

Effects of Planting Different Forage Species on Raising Soil Fertilities in Loess Hilly Regions

The experiment is conducted with three different forage species which have grown for 4 years on newly-built terrace land in loess hilly region to study the effects on raising the content of soil humus and nutrient by cultivations of Bramus inermis,Astragalus adsurgens and Meliotus albus respectly. The resoults show that the soil humus,nitrogen and phosphorus content can be significantly raised by planting the forage species,the best effect on improving soil fertilities can be obtained by planting Bromus inermis. On the other hand,the content of soil trace element changes with the different utilization of the three forage species. Although the treatment of planting Bromus inermis has the best effect,the yield of millet by planting Bromus inermis previously is relatively low. However, the millet by planting Meliotus albus previously has the highest yield among the three treatments.