甘肃两种典型盐成土不同粒径土壤颗粒中盐分离子的分布特征

Distribution characteristics of salt ions in soil aggregates with different particle diameters for two types of typical halosols in Gansu Province

以甘肃粉质黏壤土(瓜州)和砂质壤土(金昌)两种不同质地的典型盐成土作为研究对象,采用干筛法进行土壤颗粒大小分级(>5、2~5、1~2、0.5~1、0.25~0.5、<0.25 mm),探讨盐分及其离子在不同粒径土壤颗粒中的分布特征。结果表明:土壤盐分离子的分布与土壤颗粒的粒径大小有关。对于粉质黏壤土和砂质壤土,可溶性总盐、HCO_(3)^(-)、Cl^(-)、SO_(4)^(2-)、Ca^(2+)、Na^(+)均主要分布在粒径<0.25 mm的土壤颗粒中,其次是分布在粒径2~5 mm的土壤颗粒中,粒径>5 mm的土壤颗粒中分布最少。在粉质黏壤土中,可溶性总盐、HCO_(3)^(-)、Cl^(-)、SO_(4)^(2-)、Ca^(2+)、Na^(+)在粒径<0.25 mm土壤颗粒中所占百分比最高,依次为28.1%、29.7%、27.1%、32.1%、36.2%、29.3%,在粒径>5 mm土壤颗粒中所占百分比最低,依次为7.9%、9.1%、8.7%、6.1%、5.8%、7.5%;在砂质壤土中,可溶性总盐、HCO_(3)^(-)、Cl^(-)、SO_(4)^(2-)、Ca^(2+)、Na^(+)在粒径<0.25 mm土壤颗粒中所占百分比最高,依次为39.5%、45.7%、32.5%、36.6%、40.2%、31.3%,在粒径>5 mm土壤颗粒中所占百分比最低,依次为8.1%、6.7%、9.6%、8.2%、5.8%、8.8%。Mg^(2+)的分布与土壤质地类型有关,且主要分布在粒径2~5 mm或>5 mm的土壤大颗粒中。在粉质黏壤土中,Mg^(2+)在粒径2~5 mm的土壤颗粒中所占百分比最高,为24.6%,在粒径>5 mm土壤颗粒中所占百分比最低,为8.6%。在砂质壤土中,Mg^(2+)在粒径>5 mm的土壤颗粒中所占百分比最高,为32.4%,在粒径0.5~1 mm的土壤颗粒中所占百分比最低,为4.8%。

The distribution characteristics of salt ions in soil aggregates with different particle diameters significantly affect cycling,conversion,and availability of soil nutrients.In the study,with silty clay loam from Guazhou County and sand loam from Jinchang County of Gansu Province as the study objects.Based on the dry sieving method,aggregate diameters were divided into 6 grades:>5 mm,2~5 mm,1~2 mm,0.5~1 mm,0.25~0.5 mm,and<0.25 mm to explore distribution characteristics of salt ions in soil aggregates with different particle diameters.The results showed that the distribution of salty ions in soil was related to the size of soil particles.Soluble total salt,HCO_(3)^(-),Cl^(-),SO_(4)^(2-),Ca^(2+),and Na^(+)in silty clay loam and sandy loam were mostly distributed in soil aggregates with the diameter of less than 0.25 mm,followed by in the size of 2~5 mm,and their distributions in soil aggregates with the diameter of more than 5 mm were the lowest.The percentages of soluble total salt,HCO_(3)^(-),Cl^(-),SO_(4)^(2-),Ca^(2+)and Na^(+)in silty clay loam and sandy loam were both the highest in soil particles with particle size less than 0.25 mm,and the percentages are 28.1%and 39.5%,29.7%and 45.7%,27.1%and 32.5%,32.1%and 36.6%,36.2%and 40.2%,29.3%and 31.3%,respectively.These numbers were the lowest in soil particles with particle size more than 5 mm,and the percentages were 7.9%and 8.1%,9.1%and 6.7%,8.7%and 9.6%,6.1%and 8.2%,5.8%and 5.8%,7.5%and 8.8%,respectively.The distribution of Mg^(2+)was related to the type of soil texture and it was mostly distributed in soil particles with particle size in the 2~5 mm and more than 5 mm.The percentages of Mg^(2+)in silty clay loam was the highest in soil particles with particle size in the 2~5 mm,and it was 24.6%,and the lowest in soil particles with particle size more than 5 mm was 8.6%.But in sandy loam,the percentages of Mg^(2+)was the highest in soil particles with particle size more than 5 mm,and it was 32.4%,and the lowest in soil particles with particle size in the 0.5~1 mm was 4.8%.