Effects Of EN-1Ionic Stabilizer On Loess Soil And Ryegrass

EN-1ionic stabilizer is an excellent geocomposite, which is made of variety of inorganicand organic materials. It can cement soil particles and increase the stability of soil by physicaland chemical reaction with soil. Therefore, it has been gradually applied to ecologicalprotection of the side slope of Loess. In this paper, the effects of EN-1soil stabilizer on soilstructural characteristics, soil water retention, and physiological characteristics of ryegrasswere analyzed. The influences of coupled utilization of EN-1stabilizer and nitrogen fertilizeron growth and root characteristics of ryegrass and the water use efficiency were also analyzed.The main conclusions are as follows:1. The structural characteristics research of stabilized Loess soil indicate that the particlesize aggregate contents of different stabilizer amendment amount treatments under the samesoil bulk density have no significantly different in indoor soil column experiment. Largeparticle size aggregates contents of stabilized soil are higher than the control. Water-stableaggregates contents (d>0.25mm) of stabilized soil increase after10days curing. The structureof stabilized soil is more stable than the control. The distribution trend of different particlesize aggregate under different treatments of Loess soil in potted trial is similar to the indoorexperiment. The content of the water-stable aggregates (d>0.25mm) of different treatments isbetween10%~20%for Loessial soil, but more than50%for Lou soil. The water-stableaggregates content of different treatments in potted trial is significantly higher than that inindoor experiment, respectively. The stability of soil structure improves with the growth ofryegrass. The water-stable aggregates contents (d>0.25mm) is relatively higher when the soilstabilizer amendment addition is0.05%～0.10%under the same soil bulk density amount.There are significantly positive correlations between the water-stable aggregates contents(d>0.25mm) of Loess soil and the mean weigh diameter (MWD), geometric mean diameter(GMD). Meanwhile, there is a significantly negative correlation between the water-stableaggregates contents (d>0.25mm) and the fractal dimensions (D). Correlation coefficientsindexes of Lou soil are higher than Loessial soil. The influence of different treatments of Lousoil on soil structure is more obvious than that of Loessial soil. Soil structure of Lou soil ismore stable than Loessial soil. 2. Effects of EN-1stabilizer on the moisture characteristics of Loess soil show that therelationship between moisture content and soil water suction of different treatments of Loesssoil can be described by the function θ=a·S-b. The correlation coefficient of differenttreatments is highly significan（tP<0.01）for Loessial soil but significan（tP<0.05）for Lou soil.Compared to the control, EN-1stabilizer just slightly reduces the soil water-holding capacity.The stabilizer has no significantly influence on the soil effective water. EN-1stabilizer couldincrease soil hydraulic conductivity capacity, but there is not a positive correlation betweenthe capacity and the amount of soil stabilizer. The saturated hydraulic conductivity has thehighest value when the contents of stabilizer at0.05%～0.10%for Loessial soil, but at0.15%～0.20%for Lou soil. The soil saturated hydraulic conductivity decreases withincreasing soil bulk density of Loess soil whether the soil is stabilized or not. Evaporation rateof soil water of different treatments under the same soil bulk density of Loessial soildramatically reduces first but slowly reduces then. The moisture evaporation rate of Lou soilis slower than Loessial soil. The effects of different stabilizer amendment amount under thesame soil bulk density of Lou soil on cumulative evaporation show significant difference（P<0.05）, but there is not a positive correlation between the cumulative evaporation and thestabilizer content.3. The infiltration characteristics of Loess stabilized soil prove that the soil bulk densityhas significant influence on infiltration capacity at1.2～1.4g/cm3for Loessial soil and1.3～1.5g/cm3for Lou soil. The influence of soil bulk density on infiltration rate is stable andconstituent. Cumulative infiltration decreases with increasing soil bulk density. The stabilizeramount has effects on cumulative infiltration and wetting front under the same soil bulkdensity of Loess soil. The cumulative infiltration show the highest value at0.05%～0.10%amount of EN-1stabilizer for stabilized Loessial soil, and at0.05%～0.15%for stabilizedLou soil. There is a good linear relationship between the amount of cumulative infiltration andthe wetting front distance of stabilized Loess soil. The cumulative infiltration and wettingfront increase first and decrease then with increasing amount of EN-1stabilizer. Kostiakovformula is more accurate than other models when fitting the relationship between infiltrationrate and time with Philip model, Kostiakov empirical formula and index formula.4. The chlorophyll content, root activity, root/shoot ratio, root biomass and plant biomassdecrease gradually with increasing soil bulk density ranged from1.2～1.4g/cm3of Loessialsoil and1.3～1.5g/cm3of Lou soil. They increase first, and then decrease with increasingstabilizer content under the same soil bulk density of Loess soil, but all of the values are allhigher than the control. Higher stabilizer contents ranged0.05%～0.20%stress on ryegrassgrowth under low water stress conditions. Relative moisture content and chlorophyll content of ryegrass decrease, while soluble sugar content, soluble protein content, proline content andMDA content of ryegrass increase. The path analysis on the relationship between the ryegrassbiomass and indexes of soil physical and ryegrass physiological indicates show that rootactivity, water holding capacity, soil organic matter,>0.25mm water-stable aggregatescontent and hydraulic conductivity are the dominant factors on ryegrass biomass under minorwater stress conditions, but soil organic matter content,>0.25mm water-stable aggregatescontent and root activity are the dominant factors on ryegrass biomass under filling irrigationconditions. Correlations between water supply capacity, hydraulic conductivity, soil waterevaporation capacity and ryegrass biomass are not significant under filling irrigationconditions.5. Effects of EN-1stabilizer on the growth and root characteristics of ryegrass show thatthe different stabilizer amount have significant effects on height, tillers number and rootcharacteristics of ryegrass under EN-1stabilizer combined nitrogen fertilizer conditions.Height, root length and root area of ryegrass are all higher than the control. The effects ofdifferent nitrogen fertilizer amount on ryegrass biomass are not significant for Loessial soil.The root biomass, total biomass, root length and root area of ryegrass gradually increase withincreasing nitrogen fertilizer amount for Lou soil. The root area and root length of ryegrassgradually decrease with increasing soil bulk density for Loess soil. The effects of stabilizerand nitrogen on water use efficiency of ryegrass are not significant for Loessial soil. Thewater use efficiency of ryegrass increases first and decreases then with increasing stabilizeramount, and gradually increases with increasing nitrogen fertilizer for Lou soil. The linear andquadratic of soil bulk density stabilizer and nitrogen fertilizer have significant effects onryegrass biomass (P<0.01). There are highly significant correlations between ryegrassbiomass and soil bulk density, stabilizer content and nitrogen fertilizer content in a form ofnegative quadric curved lines relations. There is a certain interactive effect between soil bulkdensity and stabilizer on the ryegrass biomass by response surface and regression analysis.The best soil bulk density and stabilizer ratio is1.3g/cm3and0.15%for Loessial soil, and is1.35g/cm3and0.10%for Lou soil, respectively.