青藏高原东北缘放牧草地土壤矿物元素含量及分布特征

摘要

The status of mineral elements in surface soils of natural grazing pasture was investigated to better understand the potential effects on soil-plant-animal ecosystems.The study was conducted in 4 counties from the northeast of the Qinghai - Tibetan Plateau.Soil samples (256) from alpine meadow soil (AMS),sub-alpine meadow soil (SAMS),and marshy soil (MS) were collected from these areas,and analyzed to determine the total and available concentrations of 13 elements (Ca,P,S,K,Mg,Na,Fe,Mn,Zn,Cu,Co,Mo,and Se).The concentrations of mineral elements in soils varied with region and soil type.Total concentrations for most elements were below the national average of soils from China in one or more counties.However,the available concentrations of all mineral elements selected were above their critical levels for animal health,with the exception of Mg,P,and Se.These mineral deficiencies in soils have potential effects on the deficiency and/or imbalance of mineral elements in plants and animals.In addition,excessive Fe in soil could improve the Fe content of forage,but may eventually hamper absorption of some other mineral elements by livestock.Further research on mineral elements in plants and animals should be conducted to ascertain whether some mineral elements in soil are limiting grass and grazing livestock production in these regions.%为科学评价放牧草地土壤矿物元素含量、分布特征以及对土—草—畜矿物生态系统的潜在影响,对青藏高原东北缘的4个县(天祝、大通、玛曲、若尔盖)的土壤特征和矿物元素进行分析调查.共计采集256个来自该地区不同土壤类型(高山草甸土、亚高山草甸土、沼泽土)的表层土壤样品,分析了土壤中11种矿物元素的有效含量(Ca、P、S、K、Mg、Na、Fe、Mn、Zn、Cu和Co)和2种矿物元素(Mo和Se)全部含量.分析发现,土壤中多数矿物元素含量随着地区和土壤类型的不同而表现出一定的差异性,土壤中多数矿物元素含量与土壤有机碳和全氮呈显著正相关,相反与土壤pH有一定的负相关性.土壤中矿物元素磷和镁的有效含量均低于动物可能出现缺乏的临界值,土壤中全量硒的含量严重低于动物硒缺乏的临界值.土壤中磷、镁、硒的缺乏可能会引起该地区放牧家畜该矿物元素缺乏.另外,土壤中元素铁的有效含量远高于推荐值,土壤铁的含量过高可以引起牧草中铁的含量上升,进而影响家畜对其他元素的吸收.然而,要确认家畜是否存在该类矿物元素缺乏和不平衡问题,还需要进一步分析该地区牧草和家畜组织矿物元素含量以及家畜的生产力水平.