不同利用方式的苏打盐渍土剖面盐分组成及分布特征

COMPOSITION AND DISTRIBUTION OF SOIL SALTS IN PROFILESOF SALINE-SODIC SOIL UNDER DIFFERENT LAND USE PATTERNS

通过野外调查、采样和室内分析,研究了松嫩平原不同利用方式的苏打盐渍土剖面形态特征及可溶盐含量与组成在土壤剖面中的变化。结果表明,土壤的利用方式不同,土壤剖面腐殖质层厚度、耕层和腐殖质层的有机质含量等有明显差异。在围栏草原、旱田、新水田及老水田4个剖面中,土壤可溶盐总量、pH与ESP均是在剖面中部最高,上部和下部较低;可溶盐组成均以K++Na+和HCO 3-、CO23-为主。表明草原围栏、旱田及水田利用均有抑制苏打盐分表聚的作用。放牧草原剖面的可溶盐含量自下向上逐渐增多,盐分表聚非常显著。开垦20余年的水田剖面中,表层土壤的可溶盐总量、pH和ESP值分别降至0.21%、7.56和9.1%,表明苏打盐碱地种稻较草原和旱田利用更有利于土壤脱盐脱碱。

Through field investigation,sampling and laboratory analysis,morphological characteristics of the profiles of saline-sodic soils under different land use patterns in the Songnen Plain and variations of content and composition of the soluble salts therein were studied.Results show that under different land use patterns,the soil profiles differed sharply in thickness of humus horizon and organic matter content in the plow layer and the humus horizon.In the four profiles under fenced grassland,upland field,3-year-old paddy field and 20-year-old paddy field,separately,total content of soil soluble salts,pH and ESP were all higher in the middle layers than in the upper and lower layers.The soluble salts were mostly composed of K＋＋Na＋,HCO-3 and CO2-3,which indicate that all the four land use patterns tend to inhibit surface accumulation of sodic salt in the top layer.In grazing grassland,the total content of soil soluble salts increased with the decreasing soil depth in the profiles,showing a significant phenomenon of salt surface accumulation.In the profile under 20-year-old paddy field,the soluble salt content,pH and ESP decreased to 0.21%,7.56 and 9.1% respectively,which suggests that in alkali-saline land growing paddy rice is more contributive to soil desalinization and solodization than managing the land as grassland and upland field.