玉米连作对土壤微生物和土壤主要养分的影响

为确定河西地区玉米（Zea mays）连作的主要障碍因子，对不同连作年限的玉米田土壤微生物种群和土壤主要养分进行了常规分析。结果表明，在0～20 cm土层深处，细菌随连作年限增加呈递减趋势，与速效磷和有机质含量呈显著正相关，即速效磷和有机质均随连作年限的增加而显著减少（P<0.01）；而真菌数量随连作年限的增加而增加，与速效磷和有机质含量呈显著负相关；放线菌数量在不同连作年限呈先增后减的趋势；碱解氮和速效钾在不同连作年限没有明显的变化规律。说明玉米连作导致土壤微生物种群结构失衡，有益微生物数量减少，土壤真菌化现象严重，积累了大量植物病原菌，造成土壤主要养分减少，病害发生严重。

Effects of continuous cropping of maize on soil microbes and main soil nutrients

A field survey was carried out to investigate the effect of continuous cropping of maize with different years on soil microbes (bacteria, fungus, actinomyces) and main soil nutrients for finding the main obstacle factors of continuous cropping of maize in the Hexi area. This study showed that the quantity of bacteria in 0-20 cm soil layer significantly decreased and the number of fungus increased as the cropping years increased (P<0.01). The available P and organic matter were positively correlated to the quantity of bacteria but negatively correlated to the number of fungus. The number of actinomyces increased from the first year to the fifth year, and then decreased after the fifth year. The continuously cropping years did not affect the available K and alkali hydrolygable N. This study suggested that maize continuous planting would destroy the balance of microbe flora in soil, reducing the number of beneficial microbes and increasing the population of soil fungi, which caused the serious disease and reduced the main soil nutrients.