【摘要】 以三江平原主要土壤为试验材料进行田间、小区、盆栽试验和室内分析并补以农场调查。结果表明，与小麦、玉米相比，重茬大豆地土壤水分减少相当降水２０－４０ｍｍ；钾、磷、钼等有效养分偏低；固氮菌数减少而真菌和放线菌数增多；根系及根际土壤ｐＨ增高；土壤有机质减少；线虫危害严重。导致重茬大豆减产的绝不只是线虫一种，尚有土壤环境因素，而水分不足是主要原因。据此提出在垦区以增加土壤水分为中心的综合技术措施来缓解重茬大豆减产。更多还原

【Abstract】 Resent year,the area of continue cropping soybean wat getting more and more, people all along thought the soybean cyst nematode damage to be the main reason of reducing yield of continue-cropping soybean, Our results showed that there were many reason for reducing yield of continue cropping soybean, among the reasons,the main reason was not enough water in soil. Because this reason,it will make nematde, nutrition and microbes-system to deteriorate.The study of relationship between the nematodes and the water,the result showed it is negative correlation. Because the nematodes belong to like-air.if water increase in soil,it will decrease air and temperture in soil.So it could control nematodes to take place.The five reasons of the change of soil-environment for non-useful to devolop continue cropping soybeans is followed:1) soil water decreased.2)soil nutrition lacked,3)plant root system became alkali and soil became acid, 4) the organic matter in soil used up morely, 5)total bacterium number of fixed N decreased but other fungus and actinomyces increased, The control of reducing yield of continue cropping soybean have to use agricultural multiple measure and chemical. Also it must be used" The culture method of continue-cropping soybeans" to adapt the change of the soil- environment, not be used normal soybean culture. The area of control nematodes of dressing would be keeped by 10%.total area of suybean,because the nematodes took place only by 6% in middle and eastern of Heilongjiang province.更多还原