不同土壤改良剂对盐碱土壤化学性质和有机碳库的影响

Effect of soil conditioners on the soil chemical properties and organic carbon pool of saline–sodic soil

为研究施用不同土壤改良剂对盐碱土壤化学性质和有机碳库的影响,2016-2017年在内蒙古河套灌区盐碱土壤进行田间定位试验,设置4个实验处理:习惯处理(CK)、CK+有机土壤改良剂(M)、CK+复合土壤改良剂(G)、CK+有机土壤改良剂+复合土壤改良剂(M+G)。收集2017年收获季耕层0~20 cm土壤,测定各小区土壤中的水溶性离子含量、全盐量(TS)、钠吸附比(SAR)、pH、土壤有机碳(SOC)、活性有机碳(LOC)、微生物量碳(MBC)以及土壤碳库管理指数(CPMI),并分析各指标间的关系。结果表明:与CK相比,施用土壤改良剂各处理土壤Ca^2+含量提高了13.07%~33.33%,土壤Na^+、Cl^-和SO4^2-含量分别降低了29.83%~46.19%、12.06%~33.19%和19.90%~34.59%,土壤全盐量、钠吸附比和pH分别降低了12.67%~26.91%、33.02%~47.06%和2.21%~4.56%。其中M+G处理改良效果最好,土壤全盐量、钠吸附比和pH分别显著降低了26.91%、47.06%和4.56%(P<0.05);施用土壤改良剂各处理SOC、LOC和MBC含量分别较CK提高了18.90%~43.87%、54.55%~82.33%和64.04%~86.85%。其中M+G处理提升效果最明显,且均达到显著水平(P<0.05)。同时,施用改良剂各处理CPMI提升了95.44%~135.83%,其中M+G处理提升效果最明显,且达到显著水平(P<0.05);相关性分析表明,试验土壤LOC、MBC和CPMI均与TS和SAR呈极显著负相关关系(P<0.01),说明土壤LOC、MBC以及CPMI对盐碱土壤化学性质的变化较敏感。研究表明,施用有机土壤改良剂和复合土壤改良剂均降低了土壤含盐量、钠吸附比和pH,提升了土壤有机碳及其组分含量和土壤碳库管理指数,其中有机土壤改良剂和复合土壤改良剂配施对盐碱土壤质量的提升效果最明显。

In order to provide a theoretical basis and technical support for the utilization of soil conditioners on saline–sodic soils,this study focused on the effects of different soil conditioners on soil chemical properties and the soil organic carbon(SOC)pool.A field experiment was conducted on a saline–sodic soil in Hetao Irrigated Area of Inner Mongolia.Four treatments were designed as follows:chemical fertilizer only(CK),CK+organic soil conditioner(M),CK+composite soil conditioner(G),and CK+a combination of organic soil conditioner and composite soil conditioner(M+G).After maize was harvested in 2017,soil samples were collected from depths of between 0 and20 cm.The water-soluble salt ions content,total salt content(TS),sodium adsorption ratio(SAR),pH,SOC,labile organic carbon(LOC),microbial biomass carbon(MBC),and carbon pool management index(CPMI)were measured and analyzed using related software.The following results were obtained.Application of the conditioners increased Ca2+concentration by 13.07%~33.33%,and decreased soil Na^+,Cl^-,and SO4^2-concentrations by 29.83%~46.19%,12.06%~33.19%,and 19.90%~34.59%,respectively.Compared with the CK treatment,total salt content,SAR,and pH decreased by 12.67%~26.91%,33.02%~47.06%,and 2.21%~4.56%,respectively,under conditioner treatments.The combined application of two conditioners(M+G),which had the most pronounced effect,significantly(P<0.05)reduced total salt content,SAR,and pH by 26.91%,47.06%,and 4.56%,respectively,compared with the CK treatment.Compared with the CK treatment,SOC,LOC,and MBC increased by 18.90%~43.87%,54.55%~82.33%,and 64.04%~86.85%,respectively,under the conditioner treatments.The M+G treatment had the most significant effect on SOC,LOC,and MBC,in each case reaching a significance level of P<0.05.Furthermore,compared with the CK treatment,soil amended conditioners enhanced the CPMI by 95.44%~135.83%,with the M+G treatment having the most pronounced effect(P<0.05).Correlation analysis revealed that soil LOC,MBC,and CPMI were negatively correlated with TS and SAR,indicating that LOC,MBC,and CPMI are sensitive to changes in the chemical properties of saline–sodic soil.Application of organic and composite soil conditioners was found to be an effective measure,not only with regard to reducing soil total salt content,SAR,and pH but also for increasing SOC,soil organic carbon fractions,and the CPMI.Notably,combining the application of an organic soil conditioner and a composite soil conditioner was found to be the most effective approach under the examined experimental conditions.