施用脱硫石膏对荒漠碱土剖面土壤有机碳分布的影响

Effects of applying desulfurized gypsum on soil organic carbon distribution in profile of desert alkaline soil

石膏类钙源物对于盐碱土改良具有显著作用。为了探究施加钙源物对荒漠碱土土壤有机碳(SOC)的影响,设置以钙源物脱硫石膏施用量0、10、20、30、40 t/hm^(2)共5个处理水平,对荒漠碱土0~20 cm土层进行改良,分析改良后SOC在0~100 cm剖面上的分布、改良土层SOC的变化趋势以及影响因素。结果表明:脱硫石膏施用量为30 t/hm^(2)时,改良土层改碱效果最好,pH下降为8.24(初始值为9.97),电导率(EC)为0.98 mS/cm。脱硫石膏土壤改良对SOC的影响深度为0~40 cm,下层SOC含量无明显变化(P>0.05)。随着改良时间的增加,在15 d后SOC含量无显著变化。随着施加量的增加,当施用量为40 t/hm^(2)时,改良土层SOC含量和土壤有机碳密度(SOCD)均减少(P<0.05)。降水量和相对湿度对改良土层SOC含量减少有促进作用,作用大小:降水量>相对湿度;太阳总辐射和温度对改良土层SOC含量减少则有抑制作用,作用大小:太阳总辐射>温度。改良土层在获得最佳的碱性改良效果的同时,并不会造成SOC含量的下降。

Gypsum as calcium-based material is widely used to ameliorate saline-sodic soils.To evaluate the impacts of calcium-based application on soil organic carbon(SOC)in desert alkaline soil,a case study was conducted with different amounts of desulfurization gypsum application(0,10,20,30 and 40 t/hm^(2)).We estimated the distribution of SOC in the 0~100 cm profile,the variation trend and influencing factors of SOC in the 0~20 cm soil layer of desert alkaline soil in a period of 46 d experiments.The results showed that desulfurization gypsum application ameliorated the desert soil,and soil pH values decreased significantly in all treatment experiments.The pH was 8.24(initial 9.97)in the treatment with the amount of 30 t/hm^(2)desulfu rization gypsum,and the electrical conductivity is 0.98 mS/cm.The SOC content with the desulfurization gypsum application changed at 0-40 cm soil depth,but it had no significant change at the soil depth of 40-100 cm(P>0.05).The SOC content was in stable state(namely no change)15 d after in desulfurization gypsum application.The SOC content and density at the soil depth of 0-20 cm decreased in the treatment with 40 t/hm^(2)desulfurization gypsum.Precipitation and relative humidity accelerated the decrease in SOC content at 0-20 cm depth,with the effect size of precipitation>relative humidity,but total solar radiation and temperature slowed the decrease in SOC content at 0-20 cm depth,with the effect size of total solar radiation>temperature.Overall,our findings suggest that the addition of desulfurization gypsum<40 t/hm^(2)ameliorated saline-sodic soils but did not reduce SOC content.