Effectts Of Continuous Cropping And Rotation On Soil Microbiological And Chemical Characteristics In Gravel-sand Mulched Field

According to the phenomenon of watermelon widely planted and the land use structure change caused continuous cropping obstacles widespread presence in the arid zone of central Ningxia, in order to find ways to push the sand to the sustainable use of conducted crop rotation studies to pressure sand watermelon→soybeans→watermelon(S),watermelon→peppers→watermelon(P), watermelon→melon →watermelon (M), watermelon→oil→watermelon sunflower (O) four rotation cropping patterns and watermelon (control, CK) for research object, four different patterns of sand on the soil chemical and physical characteristics activity of crop rotation and the impact of microbial flora, Discusses the possible mechanisms regulating rotation mode continuous cropping obstacles. The main conclusions as follows:1. Continuous cropping cause the number of sickle bacteria and the blight disease index on the rise, soil PH also increased with continuous cropping increased year by year, while the overall downward trend in soil fertility, watermelon production continued to decline in the continuous cropping cultivation condition.2.Under the Continuous cropping, the total number of soil microorganisms、the number of bacteria、the value of actinomycetes and bacteria/fungi decreased, while the number of fungi increased year by year; soil Microbial biomass C、N and Basal respiration with increase in continuous cropping of declining; Continuous cropping change the soil enzyme activity, activity of soil urease and activity of soil invertase decreased with the increase of continuous cropping, soil catalase dropped after the first rise, soil alkaline phosphatase rose after the first drop.3.Under the rotation mode, soil PH were lower than continuous cropping, soil nutrient relatively even as each has a different degree of improvement, interannual which M, S, P soil organic matter, total nitrogen, total phosphorus, available phosphorus in crop rotation inter were significantly increased.4.Under the rotation mode, the total number of soil microorganisms、bacteria and actinomycetes were high than continuous cropping, fungi significantly lower than continuous cropping, inter-cropping two sizes B/F in the order of P> M> S> O> CK; soil enzyme activities for each crop rotation patterns are improved compared with even where P increased significantly; M, S, P microbial carbon, nitrogen, microbial respiration entropy and soil foundation were significantly increased. Rotation mode P, S, M changed the watermelon microbial community to take advantage of the strength of the main carbon source, P increase is more significant,168h culturing, P, S, M, increased 70.25%,2.19%,10.67%, but the AWCD value of 0 lower than continuous cropping.After crop rotation, measured productivity through field survey found that the number of sickle bacteria and blight disease index lower than continuous cropping, watermelon yields were higher than continuous cropping. P, S, M rotation mode are considered to be conducive to improving the sand field for soil microbial environment, ease watermelon continuous cropping cultivation patterns.