Effects Of Different Improvement Measures On Soil Structure And Infiltration Of Sandy Land In Yellow River Flooded Area

Soils in the yellow pan area are developed on the alluvial deposits of the Yellow River floodplain and usually need to be amended for agricultural use because of their sandy nature.In order to explore the effect of different amendment measures on sandy soils in the yellow floodplain,test plots were set up in Lankao County,Henan Province,using sandy soils as test soils and applying different materials for soil amendment measures.Field in situ tests,soil sample testing and model fitting analysis were used to investigate the characteristics of the effect of different amendment measures on soil structural and soil infiltration performance.The experimental plots were set up with four amendments of chemical fertiliser(Thf),sludge biomass charcoal(Tnt),chicken manure(Tjf)and straw(Tjg)and a control(Tck),and the main analyses were on soil infiltration,composition of force and water stable aggregates,soil bulk and porosity,soil water storage and water content under different amendments.The main results and conclusions are as follows.1.Composition of soil agglomerates and their stability characteristicsThe magnitude(%)of soil force-stable large agglomerates R_0.25(m)content in the 0-20cm soil layer under different soil amendment measures was Tnt(25.34)>Tjf(19.86)>Tjg(16.17)>Thf(7.73)>Tck(6.48)and water-stable large agglomerates R_0.25(w)content(%)was Tnt(23.00)>Tjf(17.39)>Tjg(14.17)>Thf(6.4)>Tck(4.04).The mean mass diameter MWD and geometric mean diameter GMD of soil force-stable agglomerates and water-stable agglomerates are in the same order of magnitude as those of R_0.25(m)and R_0.25(w).The fractal dimension of soil force-stable agglomerates D_mwas Tck(2.974)>Thf(2.970)>Tjg(2.936)>Tjf(2.919)>Tnt(2.893);the fractal dimension of water-stable agglomerates D_wwas Tck(2.984)>Thf(2.975)>Tjg(2.944)>Tjf(2.930)>Tnt(2.905),and the agglomerate destruction rate PAD(%)was Tck(37.65)>Thf(17.21)>Tjf(12.44)>Tjg(12.37)>Tnt(9.23).This indicates that all soil improvement measures(compared to the control)improved the composition of soil aggregates and soil structural stability to a certain extent,with Tnt being the most effective measure,followed by Tjf and Tjg,and Thf being less effective.2.Soil capacity and pore composition and their water-holding characteristicsUnder different soil amendment measures,the size of soil bulk weight?(g/cm~3)in the0-20 cm soil layer was Tck(1.63)>Thf(1.60)>Tjg(1.57)>Tjf(1.51)>Tnt(1.49),the size of total porosity?_t(%)was Tnt(47.50)>Tjf(45.79)>Tjg(43.48)>Thf(42.14)>Tck(40.62),the size of capillary porosity?_c(%)was Tnt(35.05)>Tjf(32.02)>Tjg(31.72)>Thf(28.80)>Tck(26.76),the size of non-capillary porosity?_n(%)was Tck(13.86)>Tjf(13.77)>Thf(13.34)>Tnt(12.44)>Tjg(11.75),the soil pore ratio?_c/?_n(ratio of capillary to non-capillary porosity)was Tnt(2.82)>Tjg(2.70)>Tjf(2.33)>Thf(2.16)>Tck(1.93),and the natural soil water content?(%)showed Tjf(9.14)>Tnt(8.51)>Tjg(7.63)>Thf(6.19)>Tck(6.14).This indicates that all soil improvement measures(compared to the control)improved the soil pore composition and soil water-holding properties to a certain extent,with Tnt being the most effective measure,followed by Tjf and Tjg,and Thf being less effective.3.Soil infiltration rate characteristicsThe magnitude of the surface soil initial infiltration ratef₀(mm/min)under different soil amendment measures was Tck(11.80)>Thf(11.59)>Tjf(10.64)>Tnt(8.76)>Tjg(8.31)and the magnitude of the soil stabilisation ratef_c(mm/min)was Tck(6.82)>Thf(6.80)>Tjf(6.73)>Tjg(6.60)>Tnt(5.28).This indicates that all soil improvement measures(compared to the control)reduced the infiltration rate to some extent,which had a positive effect on reducing the problem of permeable fertiliser in sandy soils,with Tnt being the better measure,followed by Tjf and Tjg and Thf being the worse.4.Model simulation of soil infiltration processThe fitting of infiltration observations using soil infiltration models(Philip,Kostiakov-lewis,Horton models)shows that the Horton model is more suitable for modelling soil infiltration processes and characteristic parameters(f₀,f_c)under different amendments.5.Correlation between soil infiltration rate and influencing factorsSoil stabilisation ratef_cwas negatively correlated with?,?_t,?_c,R_0.25(m),R_0.25(w),water stability MWD and GWD,and positively correlated with?,?_n,PAD,D_w.The regression equation for the rate of soil stabilisation and the main influencing factors is f_c=2.087-2.175?_t-1.399?_c-0.988R_0.25(m)-1.017R_0.25(w)-0.855?MWD-0.648?GWD+2.413D_w?...