石膏对苏打盐碱土壤理化性质的影响

为探究石膏对苏打盐碱土土壤理化性质的影响，通过室内模拟实验的方法，研究了土壤施用不同用量（0、0.6%、1.2%和2.4%）石膏及灌排水对土壤絮凝作用、上清液pH、上清液离子含量、土壤交换性离子含量、土壤碱化度、石膏利用率的影响。结果表明，施用石膏显著降低苏打盐碱土上清液pH及土壤碱化度，增加土壤水溶性中盐分离子含量；灌排水显著降低土壤盐分离子含量和土壤碱化度。各处理加入石膏后，上清液pH 由10.31先降至8.19～8.55后又缓慢增加；第5天时，0.6%、1.2%和2.4%石膏用量处理上清液pH分别为9.53、8.52和8.34，土壤碱化度分别下降至50.40%、33.00%和25.23%，石膏利用率分别为52.59%、58.1%和40.99%。由此可见，在试验范围内，综合土壤改良效果及石膏利用率，1.2%石膏用量为试验最优用量。

Effects of Gypsum Application on Soil Physical and Chemical Properties of Soda Saline-alkali Soil

In order to explore the effects of gypsum dosage on physical and chemical properties of soda alkali-saline soil under irrigation and drainage conditions, a laboratory simulation experiment was conducted to study the supernatant pH, supernatant ions, soil exchangeability ions, soil alkalinity, gypsum utilization rate under different dosage of gypsums (0, 0.6%, 1.2% and 2.4%). The results showed that the application of gypsum could significantly decrease pH and exchangeable sodium percentage (ESP) of soda alkali-saline soil, but increase the content of water-soluble salt ions in soil; irrigation and drainage could reduce the content of water-soluble salt ions and ESP of soil. After the application of gypsum, pH of upper liquid decreased firstly from 10.31 to 8.55～8.19, and then slowly increased over time. The soil pH values of 0.6%, 1.2% and 2.4% gypsum treatments were 9.53, 8.52 and 8.34, respectively, at the 5th day. The ESP decreased along with the irrigation and drainage. After 5 days, the ESPs of 0.6%, 1.2% and 2.4% gypsum treatments decreased to 50.40%, 33.00% and 25.23%, respectively. The utilization rates of gypsum were 52.59%, 58.1% and 40.99% under different dosage of gypsum treatments (0.6%, 1.2% and 2.4%). In consideration of the integrated soil improvement and gypsum utilization, the best dosage of gypsum was 1.2%.