Effects Of Sulfur Fertilization On Soybean Growth And Soil Microorganism And Enzyme Activity

One pot soil culture experiment was used to study the physiological and ecological effects of elemental sulfur (ES) application on two soybean species at four growth stages (profuse flowering stage, pod forming stage, pod filling stage and maturity stage). The main results were summarized as follows:1. Application of ES significantly increased dry weight of side roots, dry weight and amount of root nodules, and chlorophyll content (SPAD value) in leaves. The 30mg/kg was the suitable rate of sulphur application for getting the highest yield for high protein soybean, and 40mg/kg for high oil soybean.2.Significant differences of soil microorganism (bacterium, fungus and actinomycete) between with ES application and without ES application were determined in dependence on the rates of ES application and soybean species. The amount of soil microorganism in all treatments cropped high protein soybean followed the decrease order as bellow: 20mg/kg > 40 mg/kg > 0 mg/kg; and 40mg/kg > 20 mg/kg > 0 mg/kg for high oil soybean soil.3.Effects of ES application on the activity of peroxidase, invertase, urease, and polyphenoloxidase were in dependence on the rates of ES application, soybean species and growth stages. The best positive effect was observed at application of 20 mg/kg of ES for high protein soybean, and at application of 40 mg/kg of ES for high oil soybean. The greatest positive effect of ES application on the activity of soil peroxidase, urease was found at the pod forming stage, pod filling stage; however, The greatest positive effect of ES application on the activity of soil invertase was observed at pod filling stage of high oil soybean.4. Application of ES could increase the number of pod and seed of each plant. Application of 20 mg/kg of ES resulted in increasing of yield of high protein soybean by 12.8%, and application of 40 mg/kg of ES resulted in increasing of yield of high oil soybean by 18.5%.The present results could have an important practical significance in recommend fertilization for high quality soybean production.