外源硫输入对草地土壤-植物系统养分有效性的影响

Effects of exogenous sulfur input on nutrient availability in soil-plant system of grassland

外源硫输入增加是草地生态系统土壤酸化的一种重要诱因,在一定程度上抑制了土壤有机质的矿化从而有利于有机碳积累,但可导致石灰性土壤中碳酸盐的分解;硫输入可提高土壤中氮及微量元素铁、锰、铜、锌、硼的有效性,降低钼的有效性;导致交换性盐基离子淋失并降低钙、镁、钾的有效性;增加石灰性和中性土壤磷的有效性,而降低酸性或强酸性土壤磷的有效性。外源硫输入可促进草地植物对氮和磷的协同吸收,总体上可以促进草地植物对金属微量元素的吸收,但土壤酸化可能引起植物锰毒害,增加植物锰吸收的同时抑制了对铁的吸收。高量硫输入及土壤重度酸化可导致草地生产力和物种多样性降低;低剂量硫输入对草地生产力有一定的促进作用,但对物种多样性及群落稳定性的影响目前尚缺乏系统的研究资料。

Exogenous sulfur input is one of the most important factors that acidify grassland soils,which may inhibit mineralization of soil organic matter and facilitate organic carbon accumulation,but may contribute to the decomposition of carbonates in calcareous soils.Sulfur inputs enhance the availability of nitrogen and micronutrients(iron,manganese,copper,zinc and boron),decrease the availability of molybdenum,accelerate the leaching of exchangeable base cations,and reduce the availability of calcium,magnesium and potassium.Sulfur inputs increase the availability of phosphorus in calcareous and neutral soils,but decrease it in acid or strong acid soils.Exogenous sulfur inputs can improve the synergetic uptake of nitrogen and phosphorus by plants,and generally increase plant uptake of metallic micronutrients.Soil acidification induced by sulfur inputs might lead to plant manganese toxicity,which could increase plant manganese uptake but inhibit plant iron uptake.High inputs of exogenous sulfur and soil acidification can decline aboveground productivity and plant species diversity in grasslands.Low-dose of sulfur input tends to improve aboveground productivity,but its effects on plant species diversity and community stability remain unclear.