外源硫在草甸草原黑钙土中的转化

Transformation of Added Sulfur in Chernozem of a Meadow Grassland

    摘要
  • 摘要:
      目的  探讨元素硫添加后在草甸草原黑钙土中的氧化速率，明确土壤无机S组分的变化特征。
      方法  依托内蒙古额尔古纳草甸草原硫磺添加试验平台，测定了元素S添加量（0、1、2、4、6、8、10 t hm−2）1年后的表观氧化速率及表层土壤（0 ~ 10 cm）各无机硫组分的变化。
      结果  研究表明，对照中的土壤全硫含量为627.5 mg kg−1，其中无机硫和有机硫分别占2.4%和97.6%。硫添加处理的表土全硫含量分别比对照增加646.5 ~ 5182.5 mg kg−1，总无机硫分别比对照增加169.4 ~ 887.9 mg kg−1；硫添加处理中，表土中未氧化的元素硫分别为473.9 ~ 4264.0 mg kg−1，元素硫的表观氧化速率分别为173.5 ~ 271.3 g kg−1 a−1。在增加的表土总无机硫中，85.0% ~ 91.9%为（CaCl2浸提），7.8% ~ 17.1%为吸附性硫（ Ca(H2PO4)2浸提），0.8% ~ 1.6%为难溶性硫（HCl浸提）。土壤无机硫组分与土壤pH呈显著负相关，与土壤电导率呈显著正相关。
      结论  外源添加的元素硫主要氧化为植物可利用态的易溶性硫 和吸附性硫，而氧化为难溶性硫的比例很低。

     

    Abstract:
      Objective  To explore the oxidation rate of elemental sulfur (S) in chernozem of a meadow grassland, and to examine the changes in soil inorganic S fractions.
      Method  Based on a field experiment of S addition (with S addition rates of 0, 1, 2, 4, 6, 8 and 10 t hm−2, respectively) conducted in a meadow grassland in Erguna, Inner Mongolia, we determined the apparent oxidation rate and inorganic S fractions in 0-10 cm soil layer after 1 year of elemental S additions.
      Result  Total S content was 627.5 mg kg−1, with 2.4% inorganic S and 97.6% organic S in the treatment without elemental S addition. Soil total S content increased by 646.5-5182.5 mg kg−1, and the total inorganic S increased by 169.4-887.9 g kg−1 in the S added treatments as compared with the control. The unoxidized elemental S in the surface soil were 473.9-4264.0 g kg−1 in the S addition treatments, with an apparent oxidation rate from 173.5-271.3 g kg−1 a−1, respectively. In the total increased inorganic S, the CaCl2 extractable S (soluble S), Ca(H2PO4)2 extractable S (adsorbed S), and HCl extractable S (insoluble S) accounted for 85.0%-91.9%, 7.8%-17.1%, 0.8%-1.6%, respectively in the surface soil of the S added treatments. Soil inorganic S fractions correlated negatively with soil pH but positively with soil electric conductivity (EC).
      Conclusion  The added elemental S were mainly oxidized into plant available S, while the insoluble S only accounted for a small proportion.

     

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