中文摘要：

2003-2005年在宁南旱区将10年生苜蓿耕翻后进行了9种轮作方式的试验,研究不同轮作方式中前茬对第三年春小麦产量、土壤养分、pH值和酶活性的影响。结果表明,不同轮作方式下的第三年春小麦产量及土壤养分、pH值、酶活性各指标间差异性达到显著水平。0-60 cm土层有机质、全氮、碱解氮和速效钾平均含量均下降,降幅分别为0.05-2.24 g/kg,0.019-0.325 g/kg,0.118-12.280 mg/kg和8.87-166.88 mg/kg,pH值下降0.03-0.31。前一二年轮作作物对水肥料的消耗有叠加效应,且随耕作年限递减。轮作第一年作物对养分的消耗是主要的,而且作物种类不同,消耗量不同。第一年为春小麦的轮作方式对土壤氮素和磷素消耗最少,为谷子时次之,为马铃薯时最多。谷子是喜钾作物,前茬有谷子参与时对土壤速效钾消耗最多,有马铃薯时次之,有春小麦时最少。3种类型作物搭配组合的轮作方式,土壤有机质和速效磷含量降低最多。轮作方式中马铃薯和谷子产量高,耗水量大,导致土壤盐碱性保持较高水平。作物连作导致土壤脲酶活性降幅较大,马铃薯连作使碱性磷酸酶活性降低,禾本科作物连作的土壤蔗糖酶活性较高。

英文摘要：

After 10-growth-year alfalfa furrowed, experimentation that include 9 kinds of alfalfa-grain rotation patterns has been carried out in dried area of southern Ningxia during 2003--2005 year. It has been studied that effects of different rotation patterns on third spring wheat yields, soil nutrients,pH values and enzyme activities. The results showed that there are significant differences at above indexes of the third year rotation spring wheat of 9 kinds of alfalfa-grain rotation patterns, organic matter,total N,available N,available K average contents and pH values of 0-60 cm soil layers all decreased, which breadths is 0.05-2.24 g/kg, 0. 019-0. 325 g/kg,0.118-12.280 mg/kg,8.87-166.88 mg/kg and 0. 03-0. 31, respectively. It has cu- mulation effect that No. 1 and No. 2 year rotation grains absorb soil water and nutrients, which decrease by rotation year adds. It is dominating that rotation crops consume soil nutrient at the first rotation year and consumption quantity was different with crop species. When the first rotation crop is spring wheat, consumption of this rotation pattern＇s soil N and P is the least of all, it is second when it is millet, and it is the most when it is potato. As millet favor to available K, soil available K was use greatly when former stubble grains was millet, it is more little than millet when former stubble grains was potato, and it is the least when spring wheat. Soil organic matter and available P decrease greatly when those three grains rotate with free arrange in groups. In all rotation patterns, potato and millet use greatly soil water than spring wheat, so itlead to soil keep high alkalescence degree. In the alfalfa-grain rotation patterns, grain succession pattern induce to soil urease activity decline, which breath is more great than other patterns＇. Potato succession pattern lead to soil Alkaline Phosphatase activity fall, soil Invertase activity of crop succession pattern is more high than others.