积盐条件下土壤酸化过程的特异性研究

为探求设施内土壤积盐酸化与露地酸化的区别,人为模拟酸化和盐基淋失(自然洗盐)过程,分析洗盐前后土壤酸度特征的变化。结果表明:洗盐使电导值、有效钙(A-Ca)、交换性酸(EA)、有效阳离子交换量(CEC)、活性锰(Ac-Mn)含量均显著降低,活性铁铝(Ac-Fe、Ac-Al)含量、盐基饱和度(BSP)保持稳定或显著增高,p H显著升高。洗盐前后,土壤的EA、Ac-Al和Ac-Fe均随着p H的降低显著增高,而Ac-Mn、CEC均随着p H的降低显著下降;在出现一定量EA以后,BSP随p H降低显著下降,表明积盐酸化与露地酸化本质相同。但在等量酸加入时,设施内积盐土壤耕层酸化更快,酸害更严重,且易积盐,在治理酸化时须避免引入更多的盐分,以防加重盐害。

Specificity of soil acidification affected by salt accumulation

To explore differences between soil in open-field without salt accumulation and soil in greenhouse with salt accumulation in acidification, simulation of soil acidification and salt leaching was conducted of the soils for analysis of changes in soil acidity caused by salt leaching. Results showed that salt leaching lowered electric conductivity (EC), available Ca (A-Ca), exchangeable acid (EA), effective cation exchange capacity (CEC) and active manganese (Ac-Mn) significantly, had little effect on or increased active aluminium (Ac-Al) and iron (Ac-Fe), base saturation percentage (BSP) and pH significantly. The EA, Ac-Al and Ac-Fe increased significantly, while the Ac-Mn and CEC decreased significantly with a decrease in pH of soil with and without salt accumulation. Moreover, when a certain amount of EA appeared, BSP declined significantly with lowering pH. All these indicated that acidifications in the two soils are the same in nature, but when an equal amount of acid was added into the two soil, acidification of the plow layer of the soil with salt accumulated in greenhouse was accelerated, bringing about more severe acid damage and making the soil liable to have salt accumulation. It is, therefore, suggested that in managing soil acidification in greenhouses, it is essential to avoid introduction of more salt so as to prevent aggravation of salt damage.