Isolation Of Phosphate-solubilizing Strains And Development Of The Compound Microbial Fertilizers

Long-term unreasonabe application of chemical fertilizers,slow effect and insufficient application area and dosage of organic fertilizer,inefficiency,small-scale applications,no regional pertinence and difficult market promotion of biofertilizers resulted in a destructive soil structure,a sharp decline in organic matter content,and a seriously unbalanced soil microbial community structure,further resulting in a significant declineof the yield and quality for the agricultural products and fertilizer utilization ratio year by year.Meanwhile,due to low application efficiency and additional value,utilization area and amount of huge organic fertilizers produced by crop straw,animal manure and other agricultural waste was hindered,leading to a serious environmental pollution.For sustainable development of agriculture and requirement of farmers,application and development of compound microbial fertilizer is a future trend.For the advantage and disadvantage of chemical fertilizer,organic fertilizer and tradition bio-fertilizer,the development of compound microbial fertilizer containing characteristics of quick-efficiency for chemical fertilizer,long-quick-efficiency for organic fertilizer and enhanced-efficiency for bio-fertilizer is significant.In this paper,Bacillus amyloliquefaciens T-5 and NJN-6 which were previous isolated in our lab and demonstrated to possess efficient plant growth promotion ability,and the newly isolated phosphate-solubilizing bacterial strain Pseudomonas frederiksbergensi Y2 were utilized to produce bio-organic fertilizers and subsequently explore powdery and granular compound microbial fertilizers by adding a certain amount of chemical fertilizers.Meanwhile,storage and pot experiments were performed to verify whether the above-described method can be implemented to creat the novel powdery and granular compound microbial fertilizers.Results showed that 58 strains which possessed phosphate-solubilizing ability were first selected from the potato rhizosphere.Though quantitative determination,available phosphorus contents in the fermentation broth of strain Y40 and Y2(341.17 ?g/mL and 300.02 ?g/mL,respectively)were higher than the other strains.Treatments added with strain Y40 showed lowest pH value(4.04)than the other strains,indicating that pH was significantly correlated with phosphate-solubilizing ability.Results from the two season pot experiments showed that the biomasses of tomato,eggplant,potato,corn,and tobacco in treatments added with phosphate-solubilizing strains Y2 and Y40 were significant higher than that in blank control added with nothing,organic fertilizer treatment,and treatments added with other phosphate-solubilizing strains,indicating that the two strains could promote the growth of solanaceous.Rhizosphere colonization result showed that the two strains could effectively colonize on the root,the number of which were significantly higher than other strains.After that,the two strains Y2 and Y40 were identified as Pseudomonas frederiksbergensi and Acinetobacter calcoaceticus based on 16S rRNA sequences analysis.During the storage period for compound microbial fertilizers produced by strain T-5 and NJN-6,after 6 months,the number of living cells for the two strains in fertilizers containing 10%and 15%nutrients are all up to the national standard(>2×107 CFU/g),and survival ability of strain T-5 was better than that of the strain NJN-6.Moreover,the value in compound microbial fertilizers containing 10%nutrient was more than that containing 15%nutrients,and the water contents in the fertilizer was between 10%and 20%.The germination rates of the two strains in all compound microbial fertilizers were more than 60%.Pot experiments showed that promotion effects of granulated compound microbial fertilizers were significant better than that of the powder compound microbial fertilizers.During the storage period for compound microbial fertilizers produced by strain Y2,after 6 months,the number of living cells for the strain in fertilizers containing 10%and 15%nutrients are all up to the national standard(>2×107 CFU/g),while the number of which were significant lower than that in the bio-organic fertilizer.Moreover,the number in the compound microbial fertilizer containing 10%nutrient were significant higher than that in containing 15%nutrient.During storage,the water contents in the fertilizer were between 10%and 20%.Pot experiments showed that after application of compound microbial fertilizer containing 10%or 15%nutrients,promotion effects of compound microbial fertilizers containing 10%nutrient were significant better than that containing 15%nutrient and at this nutrient content amount,effects of granulated compound microbial fertilizers were significant better than that of the powder compound microbial fertilizers.