Effects of Continuous Cropping of Dictyophora on Soil Physical and Chemical Properties, Microbial Biomass and Enzyme Activity

The continuous obstacle of Dictyophora indusiata has become the one of the main factors affecting the healthy development of D. indusiata industry. In order to study the effects of continuous cropping of D. indusiata on the soil environment, four treatments were used in this study: no planted (CK), planted for 1 years (1Y), continuous cropping for 2 years (2Y) and continuous cropping for 3 years (3Y), to determined of the yield of D. indusiata, soil physical and chemical properties, microbial content and enzyme activity. The results showed that the yield and soil pH value decreased with the increase of continuous cropping years, and the contents of organic matter, total nitrogen, total phosphorus and total potassium, C/N and C/P also increased with the increase of continuous cropping years. Soil availability decreased with the increase of continuous cropping years, the content of alkaline nitrogen, available phosphorus and available potassium decreased by 12.25%, 28.91% and 24.86% at 3Y compared with 1Y, respectively. The biomass of bacteria, actinomycetes and fungi and the total amount of microorganism in soil increased at 1Y compared with CK, but with the increase of continuous cropping years, the biomass of bacteria and actinomycetes and the total amount of microorganism decreased significantly, while the biomass of fungi increased significantly; the continuous cropping of D. indusiata also decreased the value of bacteria/fungi in soil. The enzyme activities of the soil were higher than those of the unplanted plots, however, the activities of urease, catalase, peroxidase, sucrase, phosphatase and protease decreased with the increase of continuous cropping years. In a word, with the increase of continuous cropping, the acidity of rhizosphere soil increased, the availability of soil nutrients and the activity of soil enzymes decreased, the biomass of soil microorganisms, bacteria and actinomycetes decreased. However, the increase of fungal biomass led to the decline of soil texture.