| Chemical fertilizer plays an important role in agricultural production,and its application can effectively improve crop yield.However,long-term overdose and unreasonable chemical fertilizer application caused a series of ecological problems,such as soil acidification,compaction,salinization,organic matter degradation and water eutrophication.To achieve the green development of sustainable agriculture,developing environment-friendly fertilizer has gradually become the current research hot spot.Biochar has a large surface area,developing pore structure and powerful adsorption properties,and can absorb and hold water and nutrients.In recent years,biochar has been widely used in environmental protection and agricultural production.The relevant researches showed that adopting biochar as a carrier material based on its adsorption capacity can effectively improve the fertilizer utilization rate,increase crop yield and enhance food quality.At the same time,long-term use of biochar can effectively improve soil physical and chemical properties.Beneficial microorganisms play an important role in the agricultural production.Microbial fertilizer developed by beneficial microorganisms has developed rapidly and achieved good plant growth promotion effect;however there are still some problems in its transportation and preservation.Using biochar as a carrier material to absorb beneficial microorganisms to prepare biochar-based microbial fertilizer is expected to provide a good habitat for beneficial microorganisms,so that the function of fertilizer can be further expanded to obtain a greater range of applications and efficacy.Therefore,this paper selects seven typical biochars and analyzes their properties.The optimal preparation conditions of biochar-based microbial fertilizer were explored by studying the effects of additional amount,fermentation method of functional microorganisms,carrier types and p H values of biochars on the number of functional microorganisms in biochar-based microbial fertilizers produced by Bacillus amyloliqueficien SQR9 or Trichoderma guizhouense NJAU4742 after preservation of 7 days.At the same time,the shelf life experiment was used to explore the effect of storage time on the number of functional microorganisms in biochar-based microbial fertilizers,and pot experiment was used to evaluate the promoting effect of biochar-based microbial fertilizers on cucumber plant growth.The main findings obtained are as follows:1.Effects of addition amount of microbial suspension,fermentation method of functional microorganisms,carrier types and p H values of biochars on the number of functional microorganisms in biochar-based microbial fertilizers produced by Bacillus amyloliqueficien SQR9 or Trichoderma guizhouense NJAU 4742 after preservation of 7days were investigated.The number of Bacillus amyloliqueficien SQR9 in biochar-based microbial fertilizer showed an increasing trend first and then decreased with the increase of addition amount,and the highest value was obtained when the ratio of addition amount and carriers was 1:1.The number of Bacillus amyloliqueficien SQR9 was higher when the p H values of biochars were closer to 7.Compared with biochar carriers developed from other raw materials,biochars produced by pine,hemp stalk and rice husk(gasification)were more suitable for the preparation of biochar-based microbial fertilizers containing Bacillus amyloliqueficien SQR9.The number of Trichoderma guizhouense NJAU 4742 in biochar-based microbial fertilizer was consistent with that of Bacillus amyloliqueficien SQR9,and the highest value was also obtained when the ratio of addition amount and carriers was 1:1.Compared with Trichoderma prepared by solid state fermentation,the number of Trichoderma was more stable in the biochar-based microbial fertilizer produced by liquid fermentation suspension.The number of Trichoderma guizhouense NJAU 4742was higher when the p H values of biochars were closer to 5.Compared with biochar carriers developed from other raw materials,biochars produced by pine,hemp stalk and corn stalk were more suitable for the preparation of biochar-based microbial fertilizers containing Trichoderma guizhouense NJAU 4742.2.In the preservation experiment of biochar-based microbial fertilizer containing Trichoderma guizhouense NJAU 4742,compared with other carriers,the preservation effect of strain NJAU 4742 was better in biochar-based microbial fertilizer with biochars produced by pine,hemp stalk and corn stalk as carriers.The number of strain NJAU 4742increased when they were stored from 7 to 30 d,and the maximum number was reached at30 d.The number of strain NJAU 4742 was higher than its initial number when stored for30 d in biochar-based microbial fertilizer with biochars produced by pine,and hemp stalk as carriers.With the increase of storge time,the number of strain NJAU 4742 gradually decreased.In the preservation experiment of biochar-based microbial fertilizer containing Bacillus amyloliqueficien SQR9,compared with other carriers,the preservation effect of strain SQR9 was better in biochar-based microbial fertilizer with biochars produced by pine,hemp stalk and rice husk(gasification)as carriers.Although the number of strain SQR9decreased with the increase of storge time,the decrease speed of the number of strain SQR9was slower than that in the biochar-based microbial fertilizers prepared by other biochar as carriers.During the storge time,the number of strain NJAU 4742 in biochar-based microbial fertilizer prepared with biochars produced by pine and gasified rice shell and adjusted p H value of 5 was higher than that of in biochar-based microbial fertilizer without regulating carrier p H.After storge for 6 months,the number of strain NJAU 4742 reached2.33×10~8cfu/g,while the number in the biochar-based microbial fertilizer without adjusting the carrier p H decreased to less then 10~7cfu/g.3.The results of pot experiments showed that biochar-based microbial fertilizers produced by Bacillus amyloliqueficien SQR9 or Trichoderma guizhouense NJAU 4742both promoted the growth of cucumber plants.Compared with control,the cucumber plant height,stem diameter,fresh weight and other growth indexes were significantly increased.Biochar and functional microorganisms also have a certain effect on the growth of cucumber plants when applied alone,but the effect was weaker than that of biochar-based microbial fertilizer prepared by the two.The growth promotion effect of biochar-based microbial fertilizer produced by Bacillus amyloliqueficien SQR9 was better than that of Trichoderma guizhouense NJAU 4742.The Bacillus SQR9 biochar-based microbial fertilizer produced by Bacillus amyloliqueficien SQR9 and prepared by using pine biochar as carrier showed the best growth promotion effect on cucumber plants.In conclusion,biochar can provide a good habitat for functional microorganisms and extend the shelf-life of target benifical microbes in biochar-based microbial fertilizers.biochar-based microbial fertilizers produced by Bacillus amyloliqueficien SQR9 or Trichoderma guizhouense NJAU 4742 both promoted the growth of cucumber plants.This study provides a scientific basis for the development of environmentally friendly microbial fertilizers. |
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