| Long-term unreasonable 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 destructive soil structure, sharp decline in organic matter content, and unbalanced soil microbial community structure. This is further resulting in a significant decline in the yield and quality of 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 large wasted resources and serious environmental pollution. For sustainable development of agriculture, the application and development of compound bioorganic fertilizer (CBF) using microbes, agriculture waste and chemical fertilizers is a hot topic of research. The CBF combines the benefits of quick-nutrient supply of chemical fertilizers and long term and enhanced nutrient supply efficiency of organic fertilizers to attain maximum outputs.Bacillus amyloliquefaciens SQR9 form spores under adverse growth conditions, effectively control multiple plant diseases, promote plant growth and have been reported salt tolerant. In this study, a suitable amount of chemical fertilizer was added in bio-organic fertilizer solid-state fermented with strain SQR-9. Meanwhile, storage conditions optimization and field experiments of powder and granular compound bioorganic fertilizers were conducted to verify whether the above-described method can be implemented to create the novel CBF.The results showed that after the cultivation of a wild type strain SQR9 in high salt environment for three months and conducting the antagonism assay, a mutant sat-tolerant strain SQR9-2 was selected for further study. This strain was identified as Bacillus amyloliquefaciens based on its morphological, physiological and biochemical properties, as well as 16S rRNA analysis, indicating that the mutant sat-tolerant strain SQR9-2 was derived from the wild type strain SQR9. In the storage experiment for powdery CBF, compared to strain SQR9, the viability of strain SQR 9-2 was significantly enhanced. After six months, the mortality of strain SQR9-2 was decreased by 20.3% for bio-organic fertilizer, by 26.3% for CBF containing 30% ammonium sulfate and by 11.8% containing 50% ammonium sulfate.In the storage experiment, for bio-organic fertilizer after six months, the mortality rate of strain SQR was 49%, while the value was up to 65% for wild type strain SQR9. For granule CBF, in compound fertilizer containing 10% nutrients, the mortality rate of strain SQR9-2 and wild strain SQR9 was 45% and 60%, respectively. In CBF containing 14% and 17% nutrients, the two strains showed the similar mortality rate of approximately 27% after six months; however, in CBF containing 22% nutrients, the mortality rate of SQR9-2 was increased gradually during the 0 to 75 day-period, while a large number of cells of strain SQR9 were dead in 15 days (28%), and after six months the mortality rate was approximately 37%.In the field experiment, the CBF significantly promoted the growth of eggplant and tomato and improved the crop quality and yields. Compared to the control and to treatments amended with compound organic-inorganic fertilizer and chemical fertilizer with the same content of nutrients, treatment supplied with CBF containing 10% nutrient increased the eggplant yield by 31.2%,6.1% and 8.2%, and the tomato yield by 37.7%,8.2% and 10.3%, respectively. For treatment supplied with CMF containing 14% nutrients, the eggplant yield was increased by 34.6%,5.5% and 10.3%, and tomato yield was increased by 44.8%,7.4% and 13.9%, respectively.Granulation technology for the CMF was also studied in this research; the results showed that the particle characters were influenced by the raw material particle size. The best particle characters and minimum water requirement were observed when the raw materials were just griddled by an 18-m sieve and large and uneven particles were produced when the raw material particle size was too small. The water requirements were decreased with the increase of the amount of chemical fertilizer for producing CBF. Bio-organic fertilizer and CBF that was only added with ammonium sulfate cannot be effectively transformed into granules, while effectively granulating efficiency was observed when the NPK nutrient was added. Among chemical fertilizers, superphosphate could significantly increase the viscosity and reduced the volatility of inorganic nitrogen, while ammonium sulfate and potassium chloride were less effective. |
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