Study On The Effects Of Hydroxy Propyl Methyl Cellulose On Soil Physical And Chemical Properties And Alfalfa Growth Characteristics

The severe soil and water nutrient loss in the loess slope farmland area has led to a decrease in soil quality and agricultural non-point source pollution.In response to this issue,this article combines soil culture experiments,one-dimensional vertical infiltration experiments,and pot planting experiments to study the effects of applying hydroxypropyl methyl cellulose(HPMC)on soil water stable aggregates,absolute Zeta potential of soil colloids,soil pH,electrical conductivity,and water infiltration characteristics.It also analyzes the effects of applying HPMC on the growth indicators and photosynthetic parameters of alfalfa and clarifies the optimal application amount of HPMC.The main research results are as follows:(1)The application of HPMC can effectively increase the stability of soil structure.The content of HPMC is positively correlated with the content of water stable aggregates,the average weight diameter and the average geometric diameter of soil,and negatively correlated with the fractal dimension of soil;Applying HPMC can effectively increase the absolute value of soil colloid Zeta potential and reduce the influence of temperature on the absolute value of soil colloid Zeta potential;The effect of applying HPMC on soil acidity and alkalinity is not significant,but it can effectively increase soil conductivity;The influence of soil cultivation time on the absolute value of Zeta potential and conductivity of soil colloids shows a trend of first increasing and then decreasing;(2)Through indoor one-dimensional vertical infiltration experiments,it was found that HPMC can reduce the infiltration capacity of the soil without changing the trend of soil infiltratio.As the content and viscosity of HPMC increase,the infiltration capacity of the soil will be weakened to varying degrees.The infiltration process can be well simulated through the Philip eauation and Kostiakov formula.with determination coefficients R2>0.98.The absorption rate S,stable infiltration rate A,and empirical coefficient K significantly decrease,and the empirical index can be significantly reduced β Gradually increasing;(3)The viscosity and content of HPMC have an impact on the germination of alfalfa seeds.It was found that there is a negative correlation between the viscosity and content of HPMC.Analysis of alfalfa plant height,root length,and biomass showed that the plant height and root length of alfalfa plants first increase and then decrease with the increase of HPMC content;The optimal application method for HPMC is as follows:apply HPMC with viscosity of 5 X 104mPa、10 × 104mPa、15 × 104mPa,At the optimal application rates were 0.8,0.6,and 0.4g/kg,respectively;Simultaneously applying HPMC increases the chlorophyll content of alfalfa and enhances its photosynthesis;By fitting the light response curve of alfalfa with the right angled hyperbola model,the non right angled hyperbola model and the exponential model,the three models can better fit the light response curve of alfalfa.The root mean square error(SRMSE)and average absolute error(MAE)of the right angled hyperbola model are the smallest and the determination coefficient R2 is closer to 1,which is the best fit.