Biological and geochemical controls on phosphorus fractions in semiarid soils
Biological and geochemical controls on phosphorus fractions in semiarid soils
复制标题
DOI：
10.1023/a:1006437504494
复制
发表时间：
2001-01-01
期刊：
影响因子：
4
通讯作者：
Schlesinger, WH
中科院分区：
文献类型：
--
作者：
Cross, AF;Schlesinger, WH
本研究检测了美国新墨西哥州奇瓦瓦沙漠北部的格兰马草 - 毛垂穗草草原以及三齿拉瑞阿灌丛地表层土壤中有机磷和无机磷的浓度。在这片沙漠中，草原植被在空间上分布均匀，而单个灌木在景观中呈斑块状分布，植被对土壤养分的分布有强烈影响。大多数关于沙漠土壤中磷组分的研究主要集中在无机磷组分上，并证明了地球化学控制对土壤磷循环的重要性。此处所呈现的研究探讨了由不同植被类型决定的有机磷是否也对土壤磷循环有贡献这一问题。在年龄、地形、母质和气候条件相似的土壤中，在植被下和植被间采集样本，并按照改进的连续分级方案对磷组分进行分析。在草原和灌丛地土壤中，大部分土壤无机磷以可被盐酸和浓盐酸提取的形式存在，这表明碳酸钙对磷的有效性有控制作用。相比之下，大部分土壤有机磷与铝和铁的矿物质结合。不稳定的、植物可利用的磷组分在草原中占总磷的9.5%，在灌丛地中占6.1%。有机磷在草原的总磷库中占13.3%，在灌丛地中占12.0%。我们的研究结果表明，有机磷库可能是半干旱生态系统中一种重要但常被忽视的磷源。
This study examined the concentration of organic and inorganic phosphorus in surface soils of a Bouteloua gracilis-Bouteloua eriopoda grassland, and a Larrea tridentata shrubland, in the northern Chihuahuan Desert, New Mexico, U.S.A. In this desert where the grassland vegetation has a uniform spatial distribution and individual shrubs have a patchy spatial distribution across the landscape, vegetation strongly influences the distribution of soil nutrients. Most studies of soil phosphorus fractions in desert soils have focused primarily on inorganic P fractions and have demonstrated the importance of geochemical controls on soil P cycling. The research presented here addressed the question of whether organic phosphorus, determined by the presence of different vegetation types, also contributes to soil P cycling. Within soils of similar age, topography, parent material, and climatic regime, samples were collected under and between vegetation and analyzed for P fractions following a modified sequential fractionation scheme. Most soil inorganic P was found in the HCl- and cHCl-extractable forms in both the grassland and shrubland soils, indicating CaCO3 control over phosphorus availability. In contrast, most soil organic P was bound to Al and Fe minerals. Labile, plant-available P fractions summed to 9.5% of total P in the grassland and 6.1% in the shrubland. Organic P comprised 13.3% of the total phosphorus pool in the grassland and 12.0% in the shrubland. Our results show that the organic P pool may represent an important, yet often overlooked, source of P in semiarid ecosystems.