The Methods And Effects Of Spent Mushroom Substrate As A Kind Of Biofertilizer

The plant growth-promoting rhizobacteria (PGPR) strains from Microorganism Resources and Diversity Laboratory of Gansu Agricultural University were inoculated on spent mushroom substrate (SMS) to study the feasibility of SMS as a kind of microbial fertilizer carrier. And Inoculating nitrogen bacteria and phosphate solubilizing bacteria on SMS before composting, biological and chemical indexes in this process were measured to analyze maturity rules of SMS and to determine indexes of maturity. Then the SMS compost was applied in field to evaluate its effect on plant growth promotion. Finally, the suppressive effect of compost water extract on 10 phyotopathogenic fungi was tested. The results of the whole experiments were as follows:1. Spent mushroom substrate (SMS) could be a kind of microbial fertilizer carrier that can replace peat more suitably. Firstly it has more powerful capability of water absorbing than peat, which means better survival environment for microorganism. And the numbers of PGPR strains inoculated on it were above 108cfu/g within storage expiration of at least 135d. Furthermore, culturing alfalfa seed 36 hours and 60 hours with water extract of SMS biofertilizer in 40 days'extract of storage expiration. The germination indexes were measured. The results showed that the germination indexes of alfalfa seed cultured in 60 hours were higher than 80%, so it could be beneficial to alfalfa seed development but no phytotoxicity. Finally, Pot culture discovered that there was no significant difference between SMS biofertilizer and chemical fertilizer. All of that means SMS can replace chemical fertilizer partially or totally in alfalfa cultivation. However, Contamination was found after 105 days storing, which was suggested that the storage expiration of SMS biofertilizer should be within 4 months.2. After inoculating nitrogen fixing bacteria, phosphate solubilizing bateria, the mixture of nitrogen fixing bacteria and phosphate solubilizing bateria separately to SMS, the chemical and biological indexes were measured to research affects of plant growth promoting rhizobacteria(PGPR) on the SMS compost and their products. In the process of composting, indexes such as temperature, pH value, E4 to E6 ratio, organic carbon to organic nitrogen ratio(C/N), water-soluble carbon(WSC), water-soluble nitric-N, water-soluble ammonium-N, total (N, P, K), available(N,P,K), the number of lignocelluloses degrading microorganisms were measured, which suggested that all of the SMS compost treatments could be better matured and stabilized after composting for 2 months compared with control, and the treatments inoculated bacteria had an accelerated process of maturity to some extent. Furthermore, the treatment inoculated nitrogen fixing bacteria had the highest content of available N, and the treatment inoculated phosphate solubilizing bateria had the highest content of available P, but there were no significant changes on available K. As the number of lignocelluloses-degrading microorganisms, it dramatically decreased after the heat preservation stage.3. After analyzing correlation of chemical indexes in different composting stages, the three indexes WSC, water-soluble NH4+-N, and E4/E6 were determined as indexes of composting maturity. However, composting is an dramatically complicated process in physically and chemically which is determined by the raw materials of composting and environmental facts. So its maturity could be evaluated by the comprehensiveness of physical, chemical, and biological indexes but not those given chemical indexes.4. Appearance observation, nutrient test and field plot experiment showed that the products of SMS compsting accorded with the standard of organic fertilizer. The total nurtrients were more than 5%. Generally, the SMS compost had better growth promoting affects to Alfalfa, Perennial ryegrass, Kentucky bluegrass than the chemical control. But this effect of promotion played important role only in 25ds later. For example, the height of treatments after application of SMS compost would be 13.11-114.41% higher than that of chemical control. And the above ground biomass would be 19.93%-95.87% higher than that of chemical control. Compared within compost treatments, also the result indicated that the growth promoting effect of compost inoculated in bacteria were better than that of compost no inoculated, and the growth promoting effect of compost inoculated mixed bacteria were better than that of compost inoculated single bacteria.5. The suppressive effect of compost water extract on 10 phyotopathogenic fungi was tested by well-cut and mixed methods. The results were as follows. Compost water extract had the best inhibiting effects on Rhizoctonia solani (cotton strain) kuhn Schl, and fine inhibiting effects on Fusarium oxysporum f. Niveum, Botrytis cinerea Pers, Fusarium oxysporum (schl) f.sp cucumerinum; moderate inhibiting effect on Bipolaria maydis(Nisikado et Miyake) Shome, Rhizoctonia solani(pepper strain) kuhn Schl, Bipolaria.sorokiniana, Exserohilum turcicum (Pass) Leonard & Suggs; and the least inhibiting effect on Sclerotinia sclerotiorum (rape strain)(Lib) De Bary, Sclerotinia sclerotiorum (egg plant strain) (Lib) De Bary.