Study on combined application vermicompost with different particle sizes and fly ash and seedling effects on tomatoes
[Objective]In order to identify the best formula for tomato seedling substrate using vermicompost and two inorganic materials(expanded vermiculite and fly ash).[Methods]Different particle size ratios of vermicompost were mixed with vermic-ulite and fly ash respectively,the optimal seedling substrate formula was selected according to the multiple properties(physical and chemical properties,water absorption,water retention,and nutrient retention)and the effects on tomato seedling.[Results]The particle size ratio of earthworm castings determined the physical properties(water holding porosity,air permeability porosi-ty,and water-air ratio),while the types of inorganic material mainly affected the nutrient content of the mixed substrate.After replacing vermiculite with fly ash,the alkali nitrogen decreased by 13.10％to 24.60％,the total porosity decreased by 2.18％to 18.13％,and the water retention and nutrient retention of the substrate were reduced to varying degrees,in particular,the plant height of tomato decreased by 4.86％to 54.22％,stem diameter decreased by 1.05％to 27.63％,and fresh ground weight per plant decreased by 35.14％to 74.16％,respectively.The results of redundancy analysis showed that the seedling effect of substrate was positively correlated with ventilation porosity and water seepage rate,and negatively correlated with bulk density,the proportion of small particles and the water holding capacity of substrate capillaries.When the ratio of large particles(1.00～3.00 mm)to small particles(0.50～1.00 mm)of vermicompost was 5∶1,the seedling effect was optimal in the sub-strate treatment of expanded vermiculite and fly ash.[Conclusion]Based on the experimental results,it should be cautious the obstacles from the high bulk density,excessive water retention,and poor air permeability of small particle earthworm castings when preparing seedling substrates,and it was suggested to use larger particle earthworm castings for mixed seedling sub-strates.
万方数据
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