Analysis of nutrient management and continuous cropping obstacle factors for the main watermelon production areas in Beijing
In this paper,the nutrient management of 51 greenhouses,spring and autumn sheds in 22 villages in the 3 main watermelon producing areas in Beijing was investigated.Soil organic matter content,nutrient content,pH,electricity conductivity(EC),microorganisms and the contents of phenolic acid substances were analyzed to determine the impact of watermelon continuous cropping obstacle factors by principle component analysis.The results showed that chemical fertilizer amount seriously excessive,organic fertilizer mainly based on livestock manure and random addition of fertilizer applications,was very common during production.Most of the soil fertility in the main watermelon producing areas belonged to the classes of medium to high fertility,with significant nutrients enrichment and obvious acidification,salts accumulation,microbial community disorder and phenolic acid accumulation.The order of watermelon continuous cropping obstacle factors affected by soil factors were actinomycetes,fungi＞available phosphorus,phenolic acid＞pH,EC＞bacteria,available potassium.Therefore,the main obstacle for watermelon continuous cropping was the result of combined causes of soil microbial imbalance,phosphorus and potassium enrichment,total phenolic acid substances accumulation,soil acidification and secondary soil salinization.
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