Analysis of Four Nitrogen Fixing Sugarcane Strains Activating Soil Nutrients and Affecting Soil Enzymes
Four strains of nitrogen fixing bacteria,DX120E(Klebsiella variicola),CA1(Bacillus mycoides),WZS-021(Streptomyces chartreusi)and CN11(Pseudomonas mosselii),were used to determine the contents of nitrate nitrogen,ammonium nitrogen,alkaline hydrolyzable nitrogen,available phosphorus,inorganic phosphorus,avai-lable potassium,slowly available potassium and organic acids in soil after single and combined treatment.The optimal combination was obtained by membership function analysis,and then it was connected back to two sugarcane varieties(B8,ROC22).The contents of alkaline hydrolyzable nitrogen,available phosphorus,available potassium and the activities of catalase,alkaline phosphatase and urease in sugarcane soil were determined after different inoculation times to investigate the effects of inoculated strains on the main nutrients and soil enzymes in sugarcane soil.The results showed that:(1)The contents of nitrate nitrogen,ammonium nitrogen,alkaline hydroly-zable nitrogen,available phosphorus,available potassium,slowly available potassium and organic acids in the soil increased,while the contents of inorganic phosphorus decreased;organic acid content was positively correlated with available phosphorus content,and negatively correlated with inorganic phosphorus content.Three better treatments DX120E,CN11+DX120E and CA1+DX120E+WZS021 were obtained.(2)The results showed that the contents of alkaline hydrolyzable nitrogen,available phosphorus and available potassium in the soil of the three treatments and PAL5 were generally increased at the same time.After 90 days of treatment,the activities of three soil enzymes were significantly increased.(3)Several nitrogen fixing bacteria increased the soil nutrient content in different degrees,which may be due to the secretion of organic acids by different strains.The effect of CA1+DX120E+WZS021 on soil activation after sugarcane planting was significantly lower than that of other treatments,which may be due to the antagonistic effect of the three strains in sugarcane planting soil.The purpose of this study was to provide a theoretical basis for improving the quality of sugarcane field,promoting the development of microbial agents and reducing and increasing the efficiency of chemical fertilizer cultivation.
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