Abstract:In order to find a more efficient compound amendment, this study analyzed soil physiochemical properties and plant growth indicators by a field experiment and investigated the effects of mixed amendments of desulfurized gypsum, potassium fulvate and rice husk. The results showed that compared to CK, soil pH in 0-20 cm and 20-40 cm were reduced significantly, by 3.4%-9.0% and 4.1%-8.5%. After applying composite modifier, soil salt contents decreased, and the concentrations of HCO3-, Cl- and Na+ were decreased by 6.1%-39.4%, 18.0%-34.1% and 2.7%-33.6%, respectively. Among them, when the ratio of rice husk, potassium fulvic acid and desulfurized gypsum was 5:1.2:9 t/hm2 and15:0.4:9 t/hm2, the reduction effects of HCO3-, Cl- and Na+ were most obvious. Compared with CK, the contents of soil organic matter, available nitrogen, available phosphorus and the yield of plant were increased by 3.0%-45.8%, 16.1%-111.8%, 59.5%-154.8% and 7.1%-47.6%, respectively. Principal component analysis of evaluation on comprehensive effect proved that the optimal ratio of rice husk, potassium fulvic acid and desulfurized gypsum is 5:1.2:9 t/hm2 for biochemical compound modifiers on coastal saline-alkali soil.