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 (P0.01). 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.