Effects of shell sand content on soil physical properties and salt ions under simulated rainfall leaching

Abstract To reveal the influence of shell sand content on soil physical properties and salt ion changes under simulated rainfall leaching conditions, various ratios of shell sand to fluvo-aquic soil were simulated to change the particle composition of shell sand. Basic physical and chemical properties, such as soil particle-size composition, soil bulk density, soil porosity, soil pH, soil electrical conductivity, and soil salt ions were determined and analyzed. Fuzzy mathematics was used to evaluate the potential for soil water storage and salt suppression by altering the shell sand-to-fluvo-aquic soil ratio. The results showed that with decreasing shell sand content, the soil particle composition with different ratios of shell sand to fluvo-aquic soil changed significantly. With decreasing shell sand content, bulk density and capillary porosity of the soils with different ratios increased, and the total porosity and noncapillary porosity decreased. The soil pH first decreased and then increased, following the order 0:1 > 1:0 > 1:1 > 1:2, while the electrical conductivity increased. Cl−, NO3−, Na+, Ca2+, and Mg2+ showed a trend of first decreasing and then increasing with decreasing shell sand content, following the order 0:1 > 1:0 > 1:2 > 1:1. The mixed soil with a 1:1 ratio of shell sand and fluvo-aquic soil has the largest leaching loss of salt segregants. A comprehensive evaluation of the soil improvement performance with respect to the ratio of shell sand to fluvo-aquic soil revealed a trend of 1:1 > 1:0 > 0:1 > 1:2, and the mixed soil with a 1:1 ratio of shell sand to fluvo-aquic soil showed the greatest improvement. The shell sand content can significantly affect soil water and salt transport, and a suitable shell sand content can effectively improve soil water storage and salt inhibition effects.