Experimental Study On Formation Of Rice Seeding Raising Mat With Substrate Of Fermented Rice Straw And Biochar

Rice is one of the three major food crops in the world.China is a major producer and consumer of rice.The dominant growing patterns of rice production is seedling transplanting,and seedling raising is one of the important work of the process,However,the soil sources for standardized seedling graining has become a difficult problem in production.Meantime,the output of crops straw is abundant,and the utilization rate of straw is low.Therefore,it is of great significance to explore how to utilize crop straw and other biomass as seedling raising substrate,to replace soil.Hence,seedling raising substrate was manufactured with biochar and fermented rice straw and the substrate was compressed into seedling raising mat through single factor experiments and multiple factors experiments,to optimize the process parameters.The main works and conclusions are as follows:(1)The effects of the ratio of fermented rice straw and rice husk biochar on physical and chemical properties,nutrients of rice seedling substrates and the growth characteristics of seedlings were explored through test of substrate and rice sowing experiment.The results of the experiments showed that the substrate with weight ratio of biochar to fermented rice straw is1:4,the p H value,EC Value and nutrients of the substrate meet the requirements of rice seedling raising,and the seeding experiment showed that under this ratio,the growth of rice seedling is better than that of substrates of other ratios.(2)A press forming system equipped on WDW-200 microcomputer-controlled electronic universal testing machine was constructed and pressing head and mold were developed.,the stress analysis and optimization of the press head was carried out based on Solidworks(3)Single factor experiments were conducted to explore the influence of the material moisture content,pressure,and residence time on strength and dimensional stability of the formed seedling raising substrate mat.The suitable range of the factors were obtained,that moisture content of 25%～35%,the forming pressure of 20MPa～24MPa,the residence time of 50s～70s,and the particle size of 2.0mm.(4)The quadratic orthogonal rotation combination experiment was conducted based on single factor experiments,with factors of moisture content of substrate,press pressure,and residence time and indicators of strength and dimensional stability,the response surface method was employed to optimize the parameters..The mathematical model and regression equation between the indicators and the factors were established and the analysis of variance was conducted.The optimized parameters combination was water content of 33%,molding pressure of 23.8MPa,and pressing time of 60 s.The results may provide basis for subsequent substrate press forming research.