| With the rapid development of Chinese economy,problems such as heavy metal pollution,soil compaction and soil fertility decline caused by improper disposal of industrial and domestic waste,excessive use of chemical fertilizers and pesticides have emerged.Microbial bacterial fertilizer can improve soil structure,enhance soil fertility,promote plant growth,prevent plant diseases through its own metabolic activities.It is often mixed with chemical fertilizers and is used widely.In this study,six plant growth promoting rhizobacteria(PGPR)were isolated from maize rhizosphere,microbial fertilizer and soil contaminated by heavy metals,and microbial compound fertilizer was produced.After the expansion of the compound bacterial fertilizer,the field test was conducted to explore its effect on the growth status and soil properties of Tianta No.5 maize.Field test was carried out in April 2018 to determine the effects of compound bacterial fertilizer on the maize growth quality,soil physical and chemical properties,soil enzyme activities,and soil microbial quantity.The main results are following:(1)Five different application levels were set in this experiment,namely Y1(100% chemical fertilizer),Y2(100% bacterial fertilizer),Y3(20% bacterial fertilizer+ chemical fertilizer),Y4(50% bacterial fertilizer + chemical fertilizer),Y5(no fertilizer control),Y3 treatment was the best among these groups.Compared with Y1(100% chemical fertilizer),the plant height,stem diameter,ear height and aboveground biomass increased by 2.36%,5.23%,4.32% and 3.98%,respectively.Ear weight,carp length and ear thickness increased by 3.97%,1.44%,and 8.25%,respectively.In the results of corn yield determination,100-grain weight,economic yield,and hay yield increased by 10.04%,14.34%,and 6.27%,respectively.The determination of crude protein content in maize plants by Kjeldahl method showed that the effects of different fertilization treatments on the crude protein content of maize plants were: Y3(7.81%)>Y1(7.45%)>Y4(7.37%)>Y2(7.23%)>Y5(6.83%).(2)In order to determine soil organic matter content,total nitrogen,available phosphorus,available potassium content,potassium dichromate sulfuric acid heating method,Kjeldahl distillation method,sodium bicarbonate extraction-molybdenum antimony anti-colorimetric method,flame atomic absorption spectrophotometry were used.The results showed that the contents of organic matter,total nitrogen,available phosphorus and available potassium in the soil were significantly increasedunder the treatment of 20% microbial fertilizer mixed with chemical fertilizer.Compared with conventional application of 100% chemical fertilizer,organic matter,total nitrogen,available phosphorus,and available potassium increased by 10.75%,4.98%,4.12%,and 5.10%,respectively.The activity of catalase,alkaline phosphatase,sucrase and urease in soil were determined by volumetric method,indophenol blue colorimetric method,phenylpyrazine colorimetric method and colorimetric method.It was found that compared with conventional application of 100% chemical fertilizers,soil catalase,alkaline phosphatase,sucrase and urease activities increased by 2.71%,10.29%,9.44% and 6.47%,respectively.(3)The effect of compound bacterial fertilizer on soil microbial quantity was determined by dilution plate counting method.The results showed that compared with100% chemical fertilize,the number of bacteria,fungi and actinomycetes increased under the treatment of 20% microbial fertilizer mixed with chemical fertilizer,the total number of soil microorganisms increased by 89.27%,95.01%,8.27%,and 9.92%,respectively.In conclusion,20% compound fertilizer combined with chemical fertilizer had effects on corn growth quality,soil physical and chemical properties,soil enzyme activity and soil microbial quantity,which provided a theoretical basis for the development of mziae special fertilizer. |
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