| Pingyao County as the earliest origin place of yam has a long history in planting yam which is an important source of income for local farmers. But with the years of planting yam in the same land continuously increasing, there is some deterioration in soil properties and soil-borne diseases increased which resulting from the accumulation of the toxic substances secreted by yam plant. So there is a growing problem for the obstacle and the age of planting yam in the same land continuously gradually shortened. The sustainable cultivation of local yam hampered seriously. For this situation, the tests were carried out with the obstruction of mechanism and control measures from the following two aspects.First, the test took quality monitoring of calcareous soil in Pingyao and analyzed soil properties and ecological characteristics to get the results of yam obstacles for the following respects:1) The long yam cropping when the rhizosphere microbial flora from the high fat "bacteria-oriented" to low-fat "fungus-led". In resistance the plants in the cropping when the rhizosphere bacterial count is dominated by fungi. Even for long yam root soil actinomycetes decline is obvious.2) The balance of mineral elements in soil is easy to break because of the selective absorb nutrients of crops which impacts on competition and inhibit the absorption of certain elements crop. The crop deficiency symptom occurs resulting in yield and quality of agricultural products decline. Total nitrogen, organic matter, manganese and zinc content of cropping soil in Xiyuanci Village were higher than in Yuebei Village. After cropping continuously, the content of Xiyuanci Village decreased sharply higher than Yuebei Village which meant yam disease of Xiyuanci Village was less than Yuebei Village. At the same time, the total nitrogen, soil organic matter, manganese and zinc content had dropped significantly after continuously cropping. That the total nitrogen, organic matter, manganese, zinc content and the absorption rate were low was one of the important reasons of high incidence of Yubei Village.3) When yam cropping on plant roots secrete a self-toxicity of phenolic acids on the absorption of mineral nutrition with interference, plants reduce the concentration of the nutrients the body. Nutrient stress resulted in allelo chemicals on crop growth inhibition enhanced.Second, the test use 0681 Pioneer Fertility (effective cell count> 5 billion.g-1, pH 6.5～8.1, referred to 0681 below) and 0732 Baofengyuan Fertility (effective cell count≥5 billion.g-1, pH 6.8～7.8, referred to 0732 below) provided by Microbial Fertilizer Quality Center of Agriculture Ministry in Pingyao for the field fertilizer trials. The results of the test showed that application of fertilizer can increase soil microbial quantity and improve the soil microbial community structure.0681 soil microbial fertilizer treatment increased bacteria and actinomycetes significantly, while it reduced fungi. Compared to conventional fertilizer 0681 increased moisture content of soil organic matter and water content. And there is a significant improvement on the role of soil structure.0681 increased the test soil's ability of holding water and buffering. It improved not only soil carbon and nitrogen ratio, but also increased significantly soil available phosphorus and K. At the same time, it improve the utilization of inorganic nutrients. Through the comparison of yam disease index, we knew that application of the microbial fertilizers would help reduce the occurrence of yam's disease. |
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