| Biogas slurry,the residue of human and animal manure and crop straw after anaerobic fermentation,is a kind of high-quality organic fertilizer with comprehensive nutrient components,rapid and effective fertilization.It can not only increase production but also improve soil physical environment.At the same time,it can reduce pollution caused by chemical fertilizer and improve water shortage.In this paper,the effects of biogas slurry infiltration on soil saturated hydraulic conductivity were studied,and the laws of the effects of biogas slurry physical and chemical properties on soil saturated hydraulic conductivity were obtained.The effects of biogas slurry irrigation on soil saturated hydraulic conductivity of root facilities were further analyzed,and the effects of biogas slurry application on the growth of greenhouse tomatoes and the biological characteristics of greenhouse soil were discussed.The conclusions are as follows:(1)From the experiment of the influence of biogas slurry on the saturated hydraulic conductivity of disturbed soil,it is found that the saturated hydraulic conductivity of soil decreases with the increase of soil bulk density.Under different soil bulk density conditions,the proportion of biogas slurry,electrical conductivity,viscosity,dry matter content and pH value can affect the saturated hydraulic conductivity of soil to varying degrees.Each single factor was fitted with the saturated hydraulic conductivity of soil.It was found that the ratio of biogas slurry,electrical conductivity,viscosity and dry matter all showed different good negative exponential functions,while the pH value of biogas slurry had a good parabolic relationship with the saturated hydraulic conductivity of soil,and the goodness of fit was greater than 0.97.(2)The multiple stepwise linear regression analysis method was used to screen out the relative important factors affecting the saturated hydraulic conductivity of soil in the physical and chemical properties of biogas slurry.The results showed that the dry mass and viscosity of biogas slurry were the main factors affecting the saturated hydraulic conductivity of soil in the process of infiltration of biogas slurry.(3)In the field experiment of undisturbed facility soil,it can be found that with the increase of soil depth,the soil pH value of each biogas slurry irrigation treatment decreased by 1.25%~3.75%,and the application of biogas slurry could reduce the soil pH value.The application of biogas slurry can reduce soil bulk density and increase soil total porosity,and the sand content in different soil layers decreases with the increase of biogas slurry irrigation,while the silt and clay content gradually increases with the increase of biogas slurry proportion.Soil water content at different soil depths was not related to the proportion of biogas slurry applied,but positively related to the irrigation amount of biogas slurry.Multivariate stepwise linear regression analysis showed that soil bulk density,clay content and soil organic matter content were the main factors affecting soil saturated hydraulic conductivity in the experimental area.(4)Soil organic matter was positively correlated with the proportion of biogas slurry and the irrigation amount of biogas slurry.The relationship between soil organic matter and saturated hydraulic conductivity of each biogas slurry treatment accorded with a quadratic curve.The threshold value of organic matter for increasing saturated hydraulic conductivity of soil was 18.51g/kg.After biogas slurry irrigation,the saturated hydraulic conductivity of soil tended to increase,while the saturated hydraulic conductivity of C0 treatment decreased slightly compared with CK.(5)The effects of biogas slurry on the agronomic traits,yield and quality of greenhouse tomatoes,soil microbial flora and soil enzyme activities were found in the growth and biological characteristics tests of greenhouse tomatoes.Biogas slurry irrigation can not only improve the agronomic characteristics,quality and yield of protected tomato,but also significantly increase the number of soil bacteria,fungi,actinomycetes and the activities of soil catalase,invertase and urease.Based on the above analysis,it was found that T2 was the most suitable growth mode for tomato in each treatment(1:4,0.8Ep),which was more conducive to the growth and yield and quality of tomato. |
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