农牧交错带人工种草对土壤磷素有效性的影响

Effects of establishing perennial artificial grasslands on the availability of soil phosphorus in agro-pastoral transitional zones,Northern China

在北方农牧交错带,选择种植4年的多年生人工草地,即扁穗冰草、草地雀麦、无芒雀麦、羊草和紫花苜蓿草地,研究了人工种草对土壤磷素有效性的影响。结果表明,人工种草后土壤总有机碳含量接近天然草地水平,而人工草地土壤全磷含量、Ca-P含量显著低于天然草地,且速效磷含量均在3 mg/kg以下。人工草地土壤无机磷占全磷的比例显著低于天然草地,且人工草地土壤O-P无法检测出含量(除扁穗冰草草地)。相关分析表明土壤速效磷含量与土壤各形态无机磷均呈显著正相关关系,说明在磷素较低的石灰性土壤中,各形态无机磷都是植物所需磷素的重要来源。

The effects of establishing artificial grassland on the availability of soil phosphorus in agro-pastoral transitional zone in Northern China was studied on four year old artificial grasslands of Agropyron cristatum,Bromus riparius,Bromus inermis,Leymus chinensis and Medicago sativa.The soil total organic carbon content in artificial grassland was higher than in natural steppe soils,while the contents of total phosphorus and Ca-P were significantly lower and the content of available phosphorus was less than 3 mg/kg.The proportion of inorganic phosphorus to total phosphorus in artificial grassland was significantly lower than that in natural steppe and O-P could not be detected in artificial grassland except for A.cristatum.Correlation analysis showed that the content of available phosphorus was significantly correlated with all forms of inorganic phosphorus,indicating that they were all the main sources of phosphorus to plants in calcareous soils with lower available phosphorus.