Abstract
Abstract. Soil organic and inorganic phosphorus (P) compounds can be influenced by distinctive environmental properties. This study aims to analyze soil P composition in natural ecosystems, relating organic (inositol hexakisphosphate, DNA and phosphonates) and inorganic (orthophosphate, polyphosphate and pyrophosphate) compounds with major temporal (weathering), edaphic and climatic characteristics. A dataset including 88 sites was assembled from published papers that determined soil P composition using one-dimensional liquid state 31P nuclear magnetic resonance spectroscopy of NaOH-EDTA extracts of soils. Bivariate and multivariate regression models were used to better understand the environmental properties influencing soil P. In bivariate relationships, trends for soil P compounds were similar for mineral and organic layers but with different slopes. Independent and combined effects of weathering, edaphic and climatic properties of ecosystems explained up to 78 % (inositol hexakisphosphates) and 89 % (orthophosphate) of variations in organic and inorganic P compounds across the ecosystems, likely deriving from parent material differences. Soil properties, particularly pH, total carbon, and carbon-to-phosphorus ratios, over climate and weathering mainly explained the P variation. We conclude that edaphic and climatic drivers regulate key ecological processes that determine the soil P composition in natural ecosystems. These processes are related to the source of P inputs, primarily determined by the parent material and soil forming factors, plant and microbe P cycling, the bio-physico-chemical properties governing soil phosphatase activity, soil solid surface specific reactivity, and P losses through leaching, and finally the P persistence induced by the increasing complexity of organic and inorganic P compounds as the pedogenesis evolves. Soil organic and inorganic P compounds respond differently to combinations of environmental drivers, which likely indicates that each P compound has specific factors governing its presence in natural ecosystems.
Highlights
Phosphorus (P) is a key nutrient in animal, microbial and plant nutrition and “bears light” to terrestrial ecosystem functioning, regulating primary and secondary productivities (Walker and Adams, 1958; Vitousek et al, 2010)
Soil Pi and Po compounds responded to different combinations of explicative variables, which likely indicates that each P compound has specific factors governing its presence, transformation and persistence in ecosystems. This could be due to many factors including (i) the source of P inputs, primarily by minerals, and altogether with plant and microbe P cycling; (ii) the presence of specific phosphatase enzymes that are required to transform Pi and Po compounds into orthophosphate; and (iii) the soil specific reactivity and P losses governed by physicochemical properties; and iv) the P persistence induced by the increasing complexity of Pi and Po compounds as pedogenesis evolves
We conclude that edaphic and climatic properties are important factors in determining soil Pi and Po pools as well as their compounds, as they regulate key ecological processes governing their presence, transformation and persistence in soils. These processes are related to the source of P inputs, primarily determined by parent material and altogether through plant and microbe P cycling, the bio-physico-chemical properties governing soil phosphatase activity, soil solid surface specific reactivity and P losses through leaching, and the P persistence induced by increasing complexity of Pi and Po compounds as pedogenesis evolves
Summary
Phosphorus (P) is a key nutrient in animal, microbial and plant nutrition and “bears light” to terrestrial ecosystem functioning, regulating primary and secondary productivities (Walker and Adams, 1958; Vitousek et al, 2010). Once P has been dissolved from primary minerals, plants and microorganisms access it from the soil solution This P is recycled through soil as organic and inorganic P (Pi and Po, respectively) compounds (Noack et al, 2012; Damon et al, 2014), which are subjected to a new cycle of physico-chemical and biological reactions. Each iteration of this cycle alters the form and bioavailability of the P, leading to decreasing levels of bioavailable P compounds (McDowell et al, 2007). A better understanding of the role of the five state factors as drivers of soil P composition is crucial to quantifying the relative abundance and form of both Pi and Po pools
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