Direct chemical speciation of soil phosphorus in a Saskatchewan Chernozem after long and short-term manure amendments

Abstract

Chemical form of phosphorus (P) in soils influences both plant accessibility and solute transport of P. Soil P speciation receiving inorganic and organic fertilizers is extensively studied to address a range of agronomic and environmental concerns. It is known inorganic P sources react over long time scales in soils, but relatively few studies have focused upon long-term P speciation changes in soils receiving organic amendments. This study was conducted to address this gap by providing detailed information on the speciation of P in agricultural soils from short-(2 yr) and long-term (11 yr) applications of liquid hog manure (LHM) and solid cattle manure (SCM) made at a field research site. Chemical speciation was performed with a combination of laboratory-based soil test P extraction methods and solid-state synchrotron-based techniques. There was clear evidence that initial phosphate minerals in the manures rapidly transform into new phases after short-term soil application. The X-ray absorption near edge spectroscopy results for SCM soil samples were consistent with high solubility (likely Mg-substituted) dicalcium phosphate minerals and phosphate (PO 4) adsorption species present after short-term period, whereas long-term SCM application resulted in transformation of soil phosphate into more crystalline calcium phosphate minerals. In contrast, phosphate speciation after short term of LHM application revealed predominantly magnesium phosphate and adsorbed P compounds. Soils under long-term LHM amendment still had phosphate speciation dominated by poorly crystalline dicalcium phosphate minerals. This suggests that the manure form plays a strong role not only in short-term plant availability but also in long-term P speciation.

Molecular Scale Studies of Phosphorus Speciation and Transformation in Manure Amended and Microdose Fertilized Indigenous Vegetable Production Systems of Nigeria and Republic of Benin

“…The LCF results suggested the adsorption of P to mineral phases of Fe, organic P, and Ca phases (in some of the RF samples). These results were in line with other studies [26,31,33] that observed a dominance of adsorbed P in manure amended soils and highlighted the role of Fe in the chemistry of P in manure amended soils. In the DS, the marginal shift in the dominant P species in AT0, from 64.9% adsorbed P and 35.1% organic P (Table 3, Figure 6b) before planting to 63.9% adsorbed P and 33.1% organic P, and the occurrence of apatite P (2.9%) after harvest (Table 3, Figure 6a) were also accompanied by a reduction in the pH and total and available P after harvest (Table 3, Figure 5a,b).…”

“…The application of manure to agricultural soils is beneficial in many ways: it provides essential macronutrients such as N and P [19][20][21][22], improves soil organic matter content [23], and helps to maintain soil quality [24]. However, manures can also alter the physical and chemical properties of the soil [25], with P minerals in the soil transforming into new phases even after short term manure application [26], and pose an environmental threat to surface waters if not properly managed. The bioavailability of P in manure and manure amended soils varies with the type of manure and soil, the solubility of the P compounds in them, and the reaction products formed upon their application [20,27,28].…”

“…Therefore, understanding how the applied manure and nitrogen fertilizer influences the forms and plant availability of P is important in minimizing its negative effects on the environment [29] in any agricultural system. X-ray absorption near-edge structure (XANES) spectroscopy has been used by many researchers in studying the speciation of P in soils [26,[30][31][32][33][34][35][36][37]. This direct speciation technique is preferred because it is element specific and non-destructive [38] and it avoids bias in distinguishing different P species that can arise from chemical fractionation methods [39,40].…”

Effects of Citrate on the Rates and Mechanisms of Phosphate Adsorption and Desorption on a Calcareous Soil

“…Data were processed and analyzed with the Athena software package (Ravel and Newville, 2005). Linear combination fitting (LCF) was performed on adsorption samples with a large library of high quality phosphate reference compounds that included adsorbed phosphate, phosphate minerals with a range of cations, and organic phosphates (Kar et al, 2017; Hamilton et al, 2018). Standards were diluted in boron nitride to avoid saturation effects on XANES from self‐absorption.…”

The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy

“…In soil systems, Nuclear Magnetic Resonance, X-Ray Diffraction, and infrared techniques all have significant issues due to the need for sample extraction to overcome matrix effects and also due to low concentration of P within soils [18]. Phosphorus K-edge X-ray absorption near edge spectroscopy (XANES) is an established technique [19][20][21][22] for direct solid-state P speciation in soils that has matured as the accessibility of suitable synchrotron radiation sources and beamlines has increased [23][24][25][26]. However, the utility of P XANES spectroscopy is limited in many cases by the breadth and quality of spectral reference libraries that are used in semi-quantitative analysis.…”