| With the rapid development of China ’s agriculture,the annual output of crop straw has reached 1 billion tons,of which corn straw accounts for more than 50 %.The current situation of treatment and utilization is not good.The disorderly stacking and open burning of straw have caused serious harm to the ecological environment and public safety.Therefore,the rational treatment and utilization of straw is an urgent problem to be solved.Anaerobic fermentation technology is one of the effective ways of straw treatment.The economy of anaerobic digestion of straw is an important problem that limits the wide application of this technology.In this paper,a new type of rice seedling substrate was prepared by adding carbonized rice husk and perlite to a certain proportion of straw biogas residue composted after anaerobic fermentation,and a high value-added substrate plate was made by hot pressing.By exploring the effects of different formulations of rice seedling substrate,substrate p H and substrate maturity on rice seedling,the appropriate substrate preparation process parameters were determined.By optimizing the parameters such as matrix moisture content,molding pressure,compression time,and molding temperature during the molding process,a set of molding process parameters for preparing rice seedling substrate plates using straw biogas residue was optimized.The rice seedling substrate plate was prepared by using the optimized molding process parameters,and the planting verification test was carried out.The main research contents and results are as follows :(1)By testing the nutrient content of the matrix raw materials,the nutrient content of the soilless matrix of the machine-transplanted rice in the NY / T3838-2021 standard was≥1.5 %,and different formulations of rice seedling substrates were prepared.The commercial rice seedling substrate was CK control(the main material was peat soil).After the rice seed germination rate test and different formulations of rice seedling substrate planting test,it was determined that the mass ratio of straw biogas residue,carbonized rice husk,and perlite was 65 :27 : 8.(2)The p H optimization test of matrix formula was carried out by using the optimized rice seedling matrix formula.Taking the range of p H value 5.0～7.0 in the standard as a reference,the rice seedling planting test of different p H matrix formulas was carried out,and it was finally determined that the matrix p H was adjusted to about 5.5.(3)The straw biogas residue treated by continuous anaerobic fermentation process was further treated by aerobic composting,and its maturity was evaluated.The substrate was prepared by using straw biogas residue with different maturity,and the seedling experiment was carried out to compare the seedling effect.The results showed that the maturity of straw biogas residue had a significant effect on the effect of substrate seedling raising.The greater the maturity,the better the effect of substrate seedling raising.When the maturity evaluation index T value of straw biogas residue(terminal carbon-nitrogen ratio / starting carbon-nitrogen ratio)≤0.53,the effect of rice seedling raising substrate prepared by it was good.(4)The single factor plate test was carried out with the water content of the matrix,the molding pressure,the molding temperature and the compression time as the test factors,and the failure strength(flexural strength)of the matrix plate as the test index.It was determined that the matrix moisture content was 8%～16%,the molding pressure was 14MPa～18MPa,the molding temperature was 110°C ～150°C,and the compression time was 90s～110s.(5)Using the Box-Behnken design module in Design Expert software,the response surface analysis was carried out on the comprehensive effects of matrix moisture content,molding pressure,molding temperature and holding time on the anti-failure strength and specific energy consumption of the matrix plate.The following conclusions were obtained : The order of the influence of the four factors on the anti-failure strength of the matrix plate is molding pressure > holding time > molding temperature > matrix moisture content,and the order of the influence on the specific energy consumption is molding pressure > molding temperature >holding time > matrix moisture content;the optimal parameter combination is matrix moisture content of 11 %,molding pressure of 15 MPa,molding temperature of 110°C,and holding time of 90 s.After verification,the actual matrix plate failure strength is 135.28 k Pa,and the specific energy consumption is 11.89 k J / kg.(6)The rice seedling substrate plate pressed by the optimized molding parameters was used for rice seedling substrate planting test.The seedlings grew well.The rice seedling substrate plate with agricultural waste as the main material could replace the peat seedling substrate for rice seedling. |
