辽西北沙地苹果-大豆间作对土壤养分和微生物量分布的影响

Effects of apple-soybean intercropping on soil nutrient and microbial biomass distribution in sandy land of northwest Liaoning Province

为了解辽西北沙地果农间作系统中土壤养分及微生物量分布特征,选取研究区具有代表性的苹果(Malus pumila)-大豆(Glycine max)间作系统为研究对象,对间作系统0~60 cm土层、0~300 cm水平距离范围内的土壤养分和微生物量进行了测定,并与大豆单作、苹果单作进行对比。结果表明:辽西北沙地苹果与大豆间作系统中土壤养分十分匮乏,全氮、碱解氮、有效磷极缺乏;在水平方向上,随距苹果树距离的增加,间作系统中土壤有机质、碱解氮、全磷、有效磷总体上呈现先降低再升高后趋于平稳的变化规律;各养分竞争激烈区位于果树带区[0,100 cm);在垂直方向上,苹果与大豆间作系统各土壤养分均表现出表聚性,表土层(0~20 cm)土壤养分含量显著高于深土层(20~60 cm);土壤微生物量碳、氮在果树带区及表土层含量高,且在该区域细菌数量高;间作与单作各土壤养分、微生物量在表土层差异较大,差异性随土层加深而缩小,间作系统除碱解氮外对土壤养分表现为负效应,不能满足间作系统对土壤养分的需求,尤其对土壤氮素、磷素竞争需求量较大。综上所述,辽西北沙地苹果-大豆间作系统中存在明显的竞争关系,竞争激烈区域位于果树带区,应在此处加强氮肥和磷肥施加。

We examined the distribution characteristics of soil nutrients and microbial biomass in fruit-crop intercropping system(apple(Malus pumila)-soybean(Glycine max))in a sandy land of northwestern Liaoning.Soil nutrients and microbial biomass in the 0-60 cm soil layer and the horizontal distance of 0-300 cm in the intercropping system were measured,and further compared with that in soybean monoculture and apple monoculture.The results showed that soil nutrient was poor in the apple-soybean intercropping system,with total nitrogen,available nitrogen and available phosphorus being extremely deficient.Horizontally,with the increases of the distance from apple trees,the concentrations of soil organic matter,available nitrogen,total phosphorus and available phosphorus in the intercropping system were decreased first,then increased,and eventually tended to be stable.The nutrient competitive area was located at the fruit tree belt[0,100 cm).At the vertical direction,all types of nutrients in the apple-soybean intercropping system exhibited surface aggregation,with nutrients content in topsoil(0-20 cm)being significantly higher than that in deep soil(20-60 cm).Soil microbial biomass carbon and nitrogen and the quantity of bacteria were high in fruit tree belt and topsoil.There were significant differences of nutrient contents between intercropping and monoculture in topsoil,with the differences being narrowed with the deepening of soil layer.Except the alkaline hydrolysis nitrogen,the effects of intercropping system on soil nutrients were negative,which could not meet the requirement of intercropping system.The requirement of the intercropping system for soil nitrogen and phosphorus was substantial.In conclusion,there was an obvious competitive relationship in the apple-soybean intercropping system,especially in the fruit tree belt.The application of nitrogen and phosphate fertilizers in the intercropping system should be strengthened.