Abstract: Using continuous cropping as a contrast, the effects of different intercropping patterns of waxy maize and maize straw returning on soil microbial biomass and enzyme activities were studied. The aim was to know how intercropping and maize straw returning benefit for solving continuous cropping obstacle problems in vegetable fields. Three treatments were used, including relayintercropping mode of broccoli and waxy maize with waxy maize straw returning (B/MR-B), relayintercropping mode of broccoli and waxy maize without waxy maize straw returning (B/M-B), broccoli continuous cropping (B-B). The activities of soil urease, sucrase, neutral phosphatase and catalase, and soil microbial biomass carbon (MBC) and nitrogen (MBN) were analyzed. Relayintercropping with straw returning increased MBC and MBN, especially during the later coexistence period of maize and broccoli. Moreover, the activities of urease, neutral phosphatase and invertase were increased, and the transformation of organic nutrients in the soil was improved. Hydrogen peroxide was secreted by crop roots in the early stage of residues incorporation, which increased the activity of catalase. The intercropping system may have the potential to decrease the accumulation of hydrogen peroxide in the soil. Soil urease activity, sucrase activity, neutral phosphatase activity and catalase activity had significant positive correlations with MBC. Soil urease activity, sucrase activity, neutral phosphatase activity had significant positive correlations with MBN. Therefore, relayintercropping with straw returning can improve soil environment and reduce continuous cropping obstacles to some extent.

Key words: flood disaster, temporal-spatial difference, China., information entropy, stochastic characteristics, daily precipitation