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We investigated the potential of tailings from phosphate mining, consisting of phlogopite, carbonate minerals calcite and dolomite, and residues of apatite, to serve as a stabilizing agent in the remediation of Pb-contaminated soil in situ or on-site. In a 2.5-year field trial, test plots located in a former shooting range area were surface-treated with the tailings and analyzed for tailings-induced changes in Pb solubility and thus potential mobility within the soil profile. The factors and mechanisms controlling tailings-induced changes in Pb solubility in various soil types, and the susceptibility of Pb to leaching down the soil profile following the treatment, were investigated in supplementary laboratory-scale experiments carried out with horizon-specific soil samples collected from the field site. In the tailings-treated soil, the dissolution of the carbonate fraction of the tailings and the subsequent increase in soil pH contributed to the displacement of shot-derived Pb2+ ions by the carbonate-derived calcium ions (Ca2+) and the adsorption of Pb2+ by soil organic matter and Al, Fe, and Mn (hydr)oxide surfaces. Moreover, the apatite fraction of the tailings formed poorly-soluble compounds with Pb, particularly in soils high in exchangeable Pb2+ with respect to their cation exchange capacity. Consequently, the Pb solubility in tailings-treated soils substantially decreased. The reduction in Pb solubility was most evident in the organic topsoil high in Pb. Despite the liming effect of the tailings, and the susceptibility of Pb to form organic complexes conducive to solubilization upon an increase in pH, we found no evidence of tailings-induced leaching of Pb down the soil profile.

Metals, particularly Zn, Cu, Fe, and Mn are distributed amongst several geochemical forms, influencing their solubility, mobility and toxicity in soil-water systems. In this study, Sundarbans mangrove forest soils were analyzed by sequential fractionation to understand the distribution of these metals into exchangeable (Exch), organically bound (OrgB), Mn-oxide bound (MnOB), amorphous Fe-oxide bound (AFeOB), crystalline Fe-oxide bound (CrFeOB) and residual (Res) fractions. Soil Fe was predominately present in the residual fraction (55–73%), and manganese was primarily bounded in residual (29–58%) and MnOB (5–31%) fractions. The Res, CrFeOB and AFeOB fractions of Cu account for more than 80% of the total Cu. Zinc was mostly concentrated in the residual fraction and varied between 57 to 78% of the total Zn. Principal Component Analysis (PCA) and correlation studies revealed that exchangeable and organically bound fractions of these metals were significantly correlated, and their concentrations were highly dependent on soil pH, soil texture, organic carbon and redox potential (p < 0.05). Despite low total concentration, ratio of secondary phase and primary phase (RSP) and risk assessment code (RAC) studies showed that Cu (RSP is 1–2.64 and RAC is 1–2.89) and Mn (RSP is 1–2.42 and RAC is 1–16.66) were at low to moderate contamination risk and Fe maintained no contamination (RSP and RAC < 1) in almost all the soils. In contrast, Zn showed low contamination risk in some areas. This contamination can cause adverse effects on the plants and soil-dwelling organisms of Sundarbans mangrove forest due to higher availability. [ABSTRACT FROM AUTHOR]

The important main reason to enhance the studied calcareous soil and support changes of phosphorus fractions to reach to availability status for plant uptake. Two kinds of phosphate solubilization bacteria (PSB), (Lysinibacillus boronitolerans and Bacillus megatherium) were used to reach this target. The greatest significant results of labile P % in soil were obtained by employing a 75% P with (L. boronitolerans) treatment and 75% P with (B. megatherium + L. boronitolerans) treatment. The combine (B. megatherium and L. boronitolerans) treatments with (P50) or (P75) were superior in increasing labile phosphorus compared to other treatment alone. The results revealed that (PSB) treatments and also P rates affect significantly soil pH values compared to control where the highest pH decrease was showed in soil treated with combine (PSB) treatment either with (P50), or (P75). L. boronitolerans produced acidic phosphatase enzyme and produced alkaline phosphatase enzyme. B. megatherium doesn't produced acidic phosphatase enzyme, but produced alkaline phosphatase enzyme. L. boronitolerans produced many kinds of organic acids, while B. megatherium produced all of them except butyric acid. Treatment of 75% P with (L. boronitolerans + B. megatherium) gave high results of Spinach lengths, shoot weights, P (%), Chlorophyll A & B, Vitamins A, B, C and E., Nitrogen fixers, PSB, total microbial counts and soil Dehydrogenase enzyme. We recommend using treatment of 75% P with (L. boronitolerans + B. megatherium) to release P in calcareous sandy soils and increase crop productivity. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an indispensable nutrient for arable crops, but at the same time, contributes to excessive eutrophication in aquatic ecosystems. Knowledge about P is essential to assess the possible risks of P being transported towards vulnerable aquatic ecosystems. Our objective was to characterize P along a catena from arable and wetland soils towards aquatic sediments of a shallow lagoon of the Baltic Sea. The characterization of P in soil and sediment samples included a modified sequential P fractionation and P K-edge X-ray absorption near edge structure (XANES) spectroscopy. The concentrations of total P ranged between 390 and 430 mg kg−1 in the arable soils, between 728 and 2258 mg kg−1 in wetland soils and between 132 and 602 mg kg−1 in lagoon sediments. Generally, two sinks for P were revealed along the catena. The wetland soil trapped moderately stable P, Al-P and molybdate-unreactive P (MUP), which are most likely organically bound phosphates. Sediments at the deepest position of the catena acted as a sink for, MUP compounds among the lagoon sediments. Thus, wetlands formed by reed belts can help to prevent the direct transfer of P from arable soils to adjacent waters and deeper basins and help to avoid excessive eutrophication in shallow aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Phosphorus (P) fertilizer should be applied in a way that avoids P accumulation in the topsoil, to limit P losses in surface runoff and leaching through the soil profile. This study compared two P fertilizer regimes (annual application vs. periodic application, once every six years) for their impact on soil P chemistry, P sorption capacity and water-extractable P (WEP) in soil layers to 1 m depth in Inceptisols of northeast China, based on sequential fractionation and 31P NMR spectroscopy methods. Fertilizer regimes in the continuous corn field were: no N and P fertilizers, 0 kg P ha−1 (N fertilizer only), 25 kg P ha−1 annually, 150 kg P ha−1 every six years, 75 kg P ha−1 annually, and 450 kg P ha−1 every six years. Soil inorganic P (Pi) fractions (NaHCO3-, NaOH-, and HCl-Pi) and orthophosphate concentrations were greater with annual or periodic P application than in the control with no P fertilizer (P < 0.05). Nevertheless, annual P application led to greater accumulation (17–48%) of the soil Pi fractions and 4–28% more orthophosphates (31P NMR) than periodic P application in the 0–0.8 m soil layers. Still, soils with periodic P application had less water-extractable P (32–124%) and a higher P sorption capacity (12–26%) in the profile. Therefore, while periodic and annual P fertilizer regimes both maintain soil P fertility and sustain crop P uptake, periodic P fertilizer application (i.e., every six years) at agronomic rates should limit P losses from the soil profile. [ABSTRACT FROM AUTHOR]

Phosphorus (P) constraint can be alleviated by increasing C inputs, which can help to improve crop production and P fertilizer use efficiency. However, the effects of different manures on soil microbial biomass P (MBP) and P fractions as well as C fractions in calcareous soils remain poorly understood. Soil MBP pool involves the P mineralization and immobilization processes, potentially changing P fractions and P availability. Therefore, the effects of different manures on soil microbial biomass (MBP, MBC) pool, P, and C fractions and crop P utilization were evaluated in greenhouse experiments with maize plantation. Treatments included no manure (control), poultry manure (PM), cow manure (CM), goat manure (GM), mixed manure (MM), and three inorganic P (Pi) rates; P0: 0 mg kg-1, P50: 50 mg kg-1, and P100: P100 mg kg-1 (P2O5). For plant growth comparison, crop physiological growth indices, shoot P contents and total P uptake were increased by PM and P100 as compared to other treatments. The PM with P100 significantly increased the plant growth by inducing P uptake of ∼18% compared with control. The results exhibited that Pi (P100) combined with manure (PM) significantly (p < 0.05) increased the soil physicochemical properties, that is, 683.76 mg kg-1 total P, 21.5 mg kg-1 Olsen P, 4.26 g kg-1 SOC, 2.41 g kg-1 POC, as well as microbial biomass C and P increased by 152.84 mg kg-1 and 36.83 mg kg-1, respectively. Consequently, we concluded that PM with Pi (P100) application builds up soil microbial biomass, which is more beneficial for promoting P utilization for maize.

As the most important phenolic biopolymer in nature, lignin shows promising application potentialities in various bioactivities in vivo and in vitro, mainly including antioxidant, anti-inflammatory, hypolipidemic, and antidiabetic control. In this work, several carbon-based solid acids were synthesized to catalyze the fragmentation of organosolv lignin (OL). The generated lignin fragments, with controllable molecular weight and functional groups, were further evaluated for their application in the prevention and treatment of type 2 diabetes mellitus (T2DM). The results suggested that the urea-doped catalyst (SUPC) showed a more excellent catalytic performance in producing diethyl ether insoluble lignin (DEIL) and diethyl ether soluble lignin (DESL). In addition, the lignin fragments have a good therapeutic effect on the cell model of T2DM. Compared with the insulin resistance model, DEIL obtained by catalytic depolymerization of OL with SUPC could improve the glucose consumption of insulin-resistant cells. Moreover, low-concentration samples (50 μg/mL) can promote glucose consumption (19.7 mM) more than the traditional drug rosiglitazone (17.5 mM). This work demonstrates the prospect of depolymerized lignin for the prevention and treatment of T2DM and provides a new application field for lignin degradation products. [ABSTRACT FROM AUTHOR]

Soil legacy phosphorus (P) activation is critical for enhancing P use efficiency, while how reduced P fertilization on legacy P recovery under intercropping soil remains elusive. This study investigated the impact of fertilizer P reduction on the fertilizer P use efficiency (PUE), crop biomass, legacy P recovery, transformation and the underlying biogeochemical driving mechanisms under the maize-soybean intercropping system using a combination of sequential fractionation (SF), solution 31P nuclear magnetic resonance (P-NMR) spectroscopy and Illumina MiSeq sequencing. Four P fertilizer application rates, including conventional fertilization rate (CF), P fertilization reduction by 15 % (P15), 25 % (P25) and 50 % (P50), were conducted in the pot experiment using an Ultisol with maize-soybean intercropping. The result showed that the P15 treatment significantly increased P uptake, biomass and PUE of the maize relative to the CF treatment, but insignificantly for the soybean. The SF and P-NMR analysis revealed the depletion of total organic P (P o), while enrichment of liable P o , i.e. orthophosphate diesters in the maize rhizosphere, which probably resulted from the rhizospheric enhancement of acid phosphomonoesterase and microbial activities, and enrichment of specific bacterial communities (Candidatus_Koribacter , Ramlibacter and Noviherbaspirillum). This study provides a theoretical basis for the P fertilization reduction to enhance PUE and legacy P recovery, thus facilitate pursuing soil health and green crop production under maize-soybean intercropping system. • Maize-soybean intercropping with fertilizer P reduction could improve maize P uptake. • Enhanced ACP and microbial activities led to maize rhizospheric P o depletion. • Candidatus_Koribacter , Ramlibacter and Noviherbaspirillum participated in P o cycling. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an indispensable nutrient for arable crops, but at the same time, contributes to excessive eutrophication in aquatic ecosystems. Knowledge about P is essential to assess the possible risks of P being transported towards vulnerable aquatic ecosystems. Our objective was to characterize P along a catena from arable and wetland soils towards aquatic sediments of a shallow lagoon of the Baltic Sea. The characterization of P in soil and sediment samples included a modified sequential P fractionation and P K-edge X-ray absorption near edge structure (XANES) spectroscopy. The concentrations of total P ranged between 390 and 430 mg kg−1 in the arable soils, between 728 and 2258 mg kg−1 in wetland soils and between 132 and 602 mg kg−1 in lagoon sediments. Generally, two sinks for P were revealed along the catena. The wetland soil trapped moderately stable P, Al-P and molybdate-unreactive P (MUP), which are most likely organically bound phosphates. Sediments at the deepest position of the catena acted as a sink for, MUP compounds among the lagoon sediments. Thus, wetlands formed by reed belts can help to prevent the direct transfer of P from arable soils to adjacent waters and deeper basins and help to avoid excessive eutrophication in shallow aquatic ecosystems.

Some citrus by-products such as orange peel contains valuable compounds that could be recovered and restored into the food chain. In this study, an efficient valorization of orange peel has been investigated using green extraction, fractionation, and impregnation techniques. The first step included its extraction using CO2 and ethanol under different pressure (200–400 bar) and temperature (35–55 °C) conditions. The extracts obtained at 300 bar and 45 °C showed strong antioxidant with moderate antimicrobial activity. Then, the extract was subjected to a sequential fractionation process. The fraction obtained at 300 bar, 45 °C, and using 32% ethanol showed the strongest antioxidant and antimicrobial activity with a high extraction yield. Finally, the potential of the two best extracts (obtained at 400 bar and 45 °C before any fractionation and the fractions obtained at 300 bar, 45 °C using 32% ethanol) was determined by conducting an impregnation process to obtain an antioxidant food-grade rigid plastic that would preserve fresh food. The percentage of cosolvent (1 and 2% ethanol), the impregnation time (1 and 3 h), the pressure (200 and 400 bar), and the temperature (35 and 55 °C) were evaluated as variables of this process. The impregnated plastic showed good antioxidant and antimicrobial activities. [ABSTRACT FROM AUTHOR]

Soil use and management systems modify phosphorus (P) dynamics by changing the different P compartments. However, the interaction between land-use change and altitude is not clear. This study aimed to evaluate the effect of land use on P forms in different soil aggregate classes of Ultisols located at two altitudes. Soil samples were collected in four land-use systems (agroforestry system, secondary forest, pasture, and eucalyptus) located at two altitudes in the Atlantic Forest biome, Brazil. Phosphorus fractions were assessed using sequential fractionation. In general, recalcitrant forms represented about 70% in the agroforestry system, 66% in the eucalyptus, 65% in the pasture, and 57% in the secondary forest relative to the total P content of all land uses at both altitudes. The soil aggregate classes of smaller diameter presented higher P contents in all fractions. The smallest soil aggregate classes showed up to 65% more P than the classes with smaller diameters in the different land-use systems and altitudes. [ABSTRACT FROM AUTHOR]

Soil organic phosphorus (Po) that is hydrolyzed by phosphatases into inorganic phosphate is a source of phosphorus (P) for agricultural crops. However, the hydrolysis of Po compounds is contingent on their chemical form and stabilization in the soil matrix. We quantified three hydrolyzable Po pools (simple phosphomonoesters, phospholipids, and nucleic acids) by adding substrate-specific phosphatases to Hedley sequentially fractionated extracts from three organic soils cultivated with carrots in Southern Ontario, Canada. We observed that most of the molybdate-unreactive P was hydrolyzable in the deionized water, 0.5 mol L−1 NaHCO3, and 0.1 mol L−1 NaOH P pools (67–92%) and accounted for 14–254 kg P ha−1 in these arable organic soils. Nucleic acids represented 79% of the hydrolyzable Po in these soils but were mostly found in the 0.1 mol L−1 NaOH P pool (89%), suggesting that this Po form is bound to the soil matrix, probably to organic complexes based on the strong association between nucleic acids and total organic C (ρ = 0.805). Therefore, we propose that nucleic acids are a major hydrolyzable Po pool that are stabilized by the organic C contained in the organic soils of this study. This Po compound class should be considered in the Po biogeochemical cycle of these soils. [ABSTRACT FROM AUTHOR]

Our objective was to evaluate the impact of land use change, from natural forest to tillage-based systems, on the distribution of P pools and their stratification in soils under both no-till (NT) and conventionally tilled (CT) corn (Zea mays)-soybean (Glycine max) with and without cover crops, CT alfalfa (Medicago sativa), chicken and dairy manure, organic, and adjacent natural deciduous forest ecosystems (control). Results showed that residual P (RP) accounted for 68.7% followed by 13.3% calcium- and magnesium-bound P (CaMgP), 9.6% particulate organic P (POP), 8% iron- and aluminum-bound P (FeAlP), 0.3% soluble reactive P (SRP), and 0.1% exchangeable P (EP) of the total P. While the concentration of all P pools increased, the POP decreased at 0–10 cm depth under both CT and NT compared to the forest. The SRP increased threefold under NT, 2.6-fold under CT, sevenfold under alfalfa, and more than fourfold under organic, chicken and dairy manure systems. In contrast, the POP decreased by 63 to 73% under CT and 41 to 58% under NT. Likewise, the POP decreased under CT dairy and chicken manure, alfalfa, and organic systems. A similar tillage and cover crop impact on SRP and POP was observed at 10–20 cm depth. All P pools except POP have shown various degrees of stratification. An integration of cover crops under NT reduced the SRP stratification (by 41%), when compared to NT alone. Our results suggested that the SRP concentration and stratification in all agricultural systems are prone to edge-of-field loss either by drainage under NT or surface runoff under CT. [ABSTRACT FROM AUTHOR]

The inherent challenges posed by lignin, such as its high heterogeneity, complex structure and dark color, have impeded its widespread high-value utilization. In the present study, a green cosolvent system comprising ethanol (EtOH) and dimethyl carbonate (DMC) was employed for the fractional separation of alkali lignin. Through careful manipulation of the solvent ratio, interactions between the solvents and lignin were effectively regulated, leading to the reduction of lignin heterogeneity and the isolation of lignin fractions with distinct properties. Notably, a high yield of up to 35.65% of lignin with desirable characteristics, including a light color, low molecular weight, and high hydroxyl groups content, was achieved. Furthermore, this specific lignin fraction exhibited enhanced UV absorption and antioxidative properties, rendering it highly suitable for potential applications in sun protection products. When incorporated as micro-nano particles, it exhibited great compatibility with hand creams and elevated their sun protection factor (SPF). This innovative approach not only presents a green and straightforward lignin fractionation process but also highlights the untapped potential of lignin in the realm of sun protection applications. [Display omitted] • Lignin was fractionated by sequentially dissolving in a green ethanol/DMC cosolvent. • Lignin with light color showed enhanced UV absorption and antioxidant activity. • Light-color lignin nanoparticles were prepared and improved the SPF of hand cream. [ABSTRACT FROM AUTHOR]

The transport and fractionation of copper (Cu) were investigated in three soils which were under continuous citrus production for over 30 years. The above soils received 50 kg Cu ha−1, and were leached with eight pore volumes of water (equivalent to a total of 91 cm of rainfall). Following the completion of leaching, the leaching columns were sectioned into 5 cm depth increments for analyses of soil Cu. Concentrations of different forms of soil Cu were analyzed using a sequential fractionation procedure. The leaching column study indicated as much as 98% of the applied Cu remained in the upper 5 cm of the soil despite leaching eight pore volumes of water. Copper recovered in eight pore volumes of leachate accounted for 0.18–2.87% of Cu applied. The organically bound and precipitated forms of Cu accounted for 33–87% and 6–44% of total soil Cu, respectively.

Fertilizer-derived P is accumulated in cropland soils and their phytoavailability is variable depending on the speciation of P, which is affected by soil properties. In this study, we aimed to clarify how soil properties affect the speciation of P accumulated in fertilized soils. Soil samples were collected from the cultivated soil layers of 137 vegetable fields in Aichi prefecture, Japan. The speciation of soil P was evaluated by Truog method, sequential extraction by acetic acid, NH4F, and NaOH (Sekiya method), P K-edge X-ray adsorption near-edge structure (XANES). Phosphorus accumulated in cropland consisted predominantly of the inorganic form. Phosphorus extracted by the Truog method and acetic acid was correlated with exchangeable Ca and total C. The XANES analysis indicated that the P species extracted by Truog and acetic acid were associated with Ca, while those extracted by acetic acid also included crystalized calcium phosphate with higher crystallinity than CaHPO4, for example, hydroxyapatite. Due to the high application of P fertilizer and manure with lime, P was accumulated as calcium phosphate except for soils with relatively high contents of oxalate extractable Al and Fe. The amounts of NH4F-extracted P were higher in soils with larger amounts of oxalate extractable Al and Fe. Based on the XANES analyses, the P species extracted by NH4F were associated with Al and Fe, which is inconsistent with the operational definition of NH4F-soluble species. The P in soils extracted by NaOH was correlated with various soil properties, especially with clay content. The P species extracted by NaOH could not be identified. Our results revealed that the important factors controlling available P associated with Ca were total C and exchangeable Ca, whereas those controlling the P extracted by NH4F were oxalate extractable Al and Fe, because this fraction of P was associated with Al and Fe. [ABSTRACT FROM AUTHOR]

Some citrus by-products such as orange peel contains valuable compounds that could be recovered and restored into the food chain. In this study, an efficient valorization of orange peel has been investigated using green extraction, fractionation, and impregnation techniques. The first step included its extraction using CO2 and ethanol under different pressure (200–400 bar) and temperature (35–55 °C) conditions. The extracts obtained at 300 bar and 45 °C showed strong antioxidant with moderate antimicrobial activity. Then, the extract was subjected to a sequential fractionation process. The fraction obtained at 300 bar, 45 °C, and using 32% ethanol showed the strongest antioxidant and antimicrobial activity with a high extraction yield. Finally, the potential of the two best extracts (obtained at 400 bar and 45 °C before any fractionation and the fractions obtained at 300 bar, 45 °C using 32% ethanol) was determined by conducting an impregnation process to obtain an antioxidant food-grade rigid plastic that would preserve fresh food. The percentage of cosolvent (1 and 2% ethanol), the impregnation time (1 and 3 h), the pressure (200 and 400 bar), and the temperature (35 and 55 °C) were evaluated as variables of this process. The impregnated plastic showed good antioxidant and antimicrobial activities.

This study investigates the contents of lead, zinc, and cadmium in 109 near-surface soil samples collected around the abandoned mine of Fedj Lahdoum, northern Tunisia, to assess the risk of pollution they generate. The study involved some analytical procedures such as pH measurements, X-ray diffraction techniques, sequential fractionation, and geostatistical mapping using the ordinary Kriging techniques. The sequential fractionation revealed that the bioavailability of Pb, Zn, and Cd follows the orders F5 > F3 » F4 > F2 » F1, F5 > F3 » F4 » F2 > F1 and F5 > F2 » F4 > F1, respectively; their associations with organic matter and residual sulfides (F4) are relatively low. However, their high cumulated contents are dominantly associated with the residual (F5) and reducible (F3) fractions. The geostatistical mapping was endeavored to predict the spatial distribution of the studied heavy metals at unsampled sites and to produce a cumulated risk map of soil pollution. The latter is discussed with emphasis of the main factors responsible for the scattering of the pollution as much as the landscape conditions, the chemical composition of the mine tailings, the surface drainage of meteoric water and the wind. This study provides insight into the delineation of the spatial spreading of Pb, Zn, and Cd around the abandoned mine Fedj Lahdoum and their surrounding urban areas. It reveals that the mine infrastructure areas encompassing both extraction and processing and tailing deposition areas are the main sources of contamination. And the landscape conditions together with the surface drainage of meteoric water and the wind are the main factors responsible for the scattering of the pollution. [ABSTRACT FROM AUTHOR]

Waste stabilization ponds (WSP) used to treat dairy shed effluent hold significant loads of recoverable nutrients in the sludge. Land application of this pond sludge over grazing paddocks is a potential alternative to chemical fertilizer. Desludging of WSPs can further enhance the nutrient removal efficiency of the WSP and thereby improve the water quality of the WSP effluent and limit accumulation of phosphorus (P) in WSPs. The aim of this study was to investigate the changes in the nutrient content of soil after land application of pond sludge (PS) collected from WSP over grazing paddocks. In particular, P fractions (e.g. labile P as H2O-P and NaHCO3-P, and stable P as NaOH-P and HCl-P) were analysed in pond sludge applied soil collected from grazed paddocks. It was found that the application of PS significantly changed the composition of phosphorus in the soil compared with a control paddock that was not treated with PS. The inorganic P in the paddocks treated with pond sludge was 605 mg/kg, which was significantly higher than 67 mg/kg observed in the control paddock. Similarly, the soil treated with pond sludge exhibited increased P fractions of 245%, 36%, 47% and 3000% in terms of H2O-P, NaHCO3-P, NaOH-P and HCl-P, respectively, compared with the control paddock. The results of labile and stable P fractions in the soil samples show that PS could be a viable alternative to other forms of commercial fertilizers and a sustainable source of P for the dairy grazing paddocks. [ABSTRACT FROM AUTHOR]

Purpose: Phosphorus (P) is a crucial element for living organisms at both land and sea, but simultaneously, it can cause environmental problems especially in marine ecosystems. The pathway of P from soils through riverine and coastal systems to sea sediments has not been clarified to date. Thus, the main aim of this study was to characterize P species in sediments along a gradient from the coast of Northern Germany to the Baltic Proper. Materials and methods: Six sediment samples along a transect from river outlets into the Baltic Sea in northeastern Germany to the deep basins at the Baltic Proper were analyzed. Four complementary methods were applied to explore the different sedimentary P compounds: (i) the sequential P fractionation to extract P from sediment pools of different solubility; (ii) P K-edge X-ray absorption near edge structure (XANES) spectroscopy as an element-specific method for speciation analyses of complex environmental samples; (iii) 31P nuclear magnetic resonance (31P NMR) spectroscopy as a capable technique distinguishing especially different organic P compounds based on their characteristic resonance frequencies and (iv) scanning electron microscopy (SEM) combined with energy-dispersive X-ray microanalyses (EDX) to identify certain solid particles and their elemental composition. Results and discussion: Sequential P fractionation revealed a decrease in labile P pools (resin-P; NaHCO3-P) along with an increase in more stable P fractions (H2SO4-P; residual-P) from near-coastal sediments towards the Baltic Proper with increasing water depths of sediment deposits. In comparison, XANES analysis indicated a decline of Fe-associated P compounds in favor of Ca-bound P with increasing distance of sediments from the coastline into the Baltic Sea. Results of 31P NMR spectroscopy showed that the variety of different mono- and diester P compounds decreased with increasing distance from the coast and that high proportions of orthophosphate (ortho-P) were present especially in greater water depths. The SEM-EDX analysis supported most of these results by retriving Fe phosphate particles especially in the sediments near the coast. Conclusions: The integration of several P-specific methods enabled improved insights into P speciation. A trend towards more stable Ca-P compounds towards the Gotland basin was found with sequential fractionation and P-XANES. In the future, different types of sediments will be analyzed with respect to their interactions with adjacent soils to find out a common principle of P-transformations and derive approaches for capturing P before entering susceptible marine systems. [ABSTRACT FROM AUTHOR]

The transport and fractionation of copper (Cu) were investigated in three soils which were under continuous citrus production for over 30 years. The above soils received 50 kg Cu ha−1, and were leached with eight pore volumes of water (equivalent to a total of 91 cm of rainfall). Following the completion of leaching, the leaching columns were sectioned into 5 cm depth increments for analyses of soil Cu. Concentrations of different forms of soil Cu were analyzed using a sequential fractionation procedure. The leaching column study indicated as much as 98% of the applied Cu remained in the upper 5 cm of the soil despite leaching eight pore volumes of water. Copper recovered in eight pore volumes of leachate accounted for 0.18–2.87% of Cu applied. The organically bound and precipitated forms of Cu accounted for 33–87% and 6–44% of total soil Cu, respectively. [ABSTRACT FROM AUTHOR]

Potato crops generally require high amounts of phosphorus (P) fertilizer to reach economically acceptable yields. However, high inputs of P not only increase production cost, but also may increase the environmental risk of P runoff. We evaluated soil test P and sequentially-extracted P in soil samples from 10 potato fields which had three-year crop rotations with or without irrigation. Whereas soil test (Olsen) P was not significantly influenced by crop rotation and irrigation, P levels in sequentially-extracted fractions were impacted by management. The impact of crop rotation was mainly expressed on water extractable P. Irrigation had greater influence on stable P extracted in NaOH and HCl fractions. Higher levels of NaOH extractable inorganic P were observed in soil from irrigated fields, while higher levels of HCl extractable P were observed insoils under rainfed management. Our data indicate that crop management practice may eventually affect P availability and runoff potential in these potato soils over the long term.However, more field data from longer experimental periods are needed to confirm this hypothesis.

Hexi Corridor is one of the most important base of vegetable producing areas in China. Livestock manure (LM) applied to agricultural field could lead to soil heavy metal (HM) pollution. Previous studies have focused on HM pollution following LM application in acidic polluted soils; however, fewer studies have been conducted in alkaline unpolluted soils. A 4–year field vegetable production experiment was conducted using pig manure (PM) and chicken manure (CM) at five application rates (0, 15, 30, 45, and 60 t ha−1) to elucidate potential risks of HMs in an alkaline unpolluted soil in the Hexi Corridor oasis agricultural area and HM uptake by Chinese cabbage. The results showed that LM application caused a significant build–up of Cu, Zn, Pb, Cd, and Ni content in topsoil by 30.6–99.7%, 11.4–51.7%, 1.4–31.3%, 5.6–44.9%, 14%–40.8%, respectively. The Cd, Cu, Zn could potentially exceed the soil threshold in next 8–65 years after 15–60 t ha−1 LM application. Under LM treatment, the soil DTPA–extractable Cu, Zn, Fe, the acid–extractable fraction of Cu, Zn, Fe, Cd, Ni, and the Oxidable fraction of Cu, Zn, Fe, Mn, Cd, Ni significantly increased, but the DTPA–extractable Pb, Cd, the acid–extractable fraction of Pb, and the reducible fraction of Cd significantly decreased. Cu and Zn could migrate to the deeper soil and relatively increase in DTPA–extracted Cu, Zn were found in 20–40 cm soil depth after LM application. The pH and SOM could influence the bioavailability of HMs in soil. The bioaccumulation factor and transfer factor (TF) values were <1 except Mn (TF > 1). HMs in leaf did not approach the threshold for HM toxicity due to the "dilution effect". Recommend the type of manure was the PM and the annual PM application rate was 30 t ha−1 to ensure a 20–year period of clean production in alkaline unpolluted Fluvo–aqiuc vegetable soils. [Display omitted] • The accumulation of Cu, Zn, Pb, Cd, Ni was observed in topsoil after LM application. • Potential risks of Cd, Cu and Zn in topsoil in next 8–65 years after 15–60 t ha−1 LM application were estimated. • LM application increased contents of acid-extractable fraction of Cu, Zn, Fe, Cd, Ni. • The bioaccumulation and transfer factor values were <1 except Mn. • Contents of HMs in edible part did not approach the threshold for HM toxicity. [ABSTRACT FROM AUTHOR]

Composting is a sustainable method for recovering nutrients from various organic wastes, including food waste. Every input waste has different nutrient contents, in turn, suggesting that every compost has different fertilizer and/or soil improvement values. The phosphorus (P) concentration and relative distribution of P forms is related to the original organic material. The relative distribution of P forms determines how readily plants can absorb P from the compost-amended soil. The aim of this study was to investigate the content and relative share of P forms in composts made from fish waste, sewage sludge, green waste, and horse manure. Six forms of P (labile; bound to reducible metals; bound to non-reducible metals; bound to easily degradable organic material; and bound to calcium) were determined using sequential extraction method. The results indicated that fish waste compost had relatively high proportion of labile P, suggesting good biological availability. In comparison, sewage sludge compost contained the highest overall P concentration per dry weight unit, while labile P constituted only 6% of summary of P forms. The results indicate that the evaluation of composts as alternative P sources in agriculture should rely on the relative distribution of P forms in the compost in addition to the typically recognized value of the total P.

Interaction of Cu (II) ions with the matrix of soil and mineral phases of layered silicates was assessed by the Miller method of selective sequential fractionation and a set of synchrotron X-ray methods, including X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XANES). It was shown that the input of Cu into Calcic Chernozem in the form of monoxide (CuO) and salt (Cu(NO3)2) affected the transformation of Cu compounds and their affinity for metal-bearing phases. It was found that the contamination of soil with a soluble Cu(II) salt increased the bioavailability of the metal and the role of organic matter and Fe oxides in the fixation and retention of Cu. During the incubation of soil with Cu monoxide, the content of the metal in the residual fractions increased, which was related to the possible entry of Cu in the form of isomorphic impurities into silicates, as well as to the incomplete dissolution of exogenic compounds at the high level of their input into the soil. A mechanism for the structural transformation of minerals was revealed, which showed that ion exchange processes result in the sorption of Cu (II) ions from the saturated solution by active sites on the internal surface of the lattice of dioctahedral aluminosilicates. Surface hydroxyls at the octahedral aluminum atom play the main role. X-ray diagnostics revealed that excess Cu(II) ions are removed from the system due to the formation and precipitation of coarsely crystalline Cu(NO3)(OH)3.

Knowledge on P release characteristics and availability of different forms of soil phosphorus can be useful for crop production. Kinetics of P release and distribution of inorganic P from in calcareous soils at summit, shoulder, back slope, foot slope and toe slope of three soil toposequences (Fars province southern Iran) were determined and the relationship between P release and soil properties with phosphorus form was investigated. The kinetics of P release in the soils was determined by successive extraction with 0.01 M CaCl2 over a period of 72 hours. The kinetics of P release followed Elovich, power function and first order kinetic models. The results demonstrated that the pattern of P desorption was similar in all topographic units of the three regions at all times. The highest amount of P release was observed in the lower part of the slope specially in Eghlid and Abadeh (xeric and aridic regimes). Generally, the average content of cumulative phosphorus release and most forms of phosphorous and physical and chemical characteristics in Eghlid soils were greater than other studied soils. Different P forms were determined by sequential extraction; the fractionated inorganic P forms namely apatite type and dicalcium phosphate possessed the highest and the lowest amounts of P reserve in the soils, respectively. As a result, P release and various P forms distribution within the soil profiles along toposequences varied in different topographic units and increased down the slope with an irregular trend. Due to such variability, P fertilizers are recommended by consideration of the physiographic units. [ABSTRACT FROM AUTHOR]

Four fractions separated sequentially from a coal tar pitch by two different methods are examined by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI TOF‐MS) and 50/24 matrix analysis, to evaluate both separation effectiveness and characteristics of large polycyclic aromatic hydrocarbons (PAHs) in variable fractions. Both Soxhlet extraction and anti‐solvent precipitation can sequentially produce four fractions that have narrower molecular mass distribution with specific structural features of PAHs. The results show that the overall molecular mass (MM) and ring size of large PAHs abundant in the fractions gradually shift to higher values as solvent strength increases, with some overlap between two adjacent fractions. A broad range of peaks in MS spectra has been resolved as 4‐ to about 25‐ ring PAHs by 50/24 matrix analysis, with some detailed molecular structure elucidated. For example, the PAHs in the light HS fraction include 4 to 11‐ring aromatics with more ortho‐condensed structure. On the other hand, heavier fractions contain more aromatic rings fused by bay‐condensations that result in quaternary aromatic carbons. Besides structural insights, SEM morphologically reveals differences in the extraction effectiveness between Soxhlet and anti‐solvent, due to mass transfer and diffusion limitations in bituminous material. [ABSTRACT FROM AUTHOR]

Alkali lignin pyrolysis oil (PO) was subjected to a sequential extraction method in which PO was separated into water soluble (WS), water insoluble (WI), methanol soluble (MS), methanol insoluble (MI), dichloromethane soluble (DS), and dichloromethane insoluble (DI) subfractions via combinations of water and organic solvents (water, methanol, and dichloromethane). Several analytical techniques were used to characterize PO and its subfractions. Elemental analysis showed that the higher heating value (HHV) of DS was highest, and there was higher aromaticity in the MI fraction, while the DI fraction had lower aromaticity. Interestingly, gas chromatography-mass spectrometry (GC-MS) and positive ion electrospray high resolution mass spectrometry (ESI+-HRMS) analyses showed that both the MI and DI subfractions were lignin-derived oligomers, which accounted for 25.0% of the total mass of the original PO. Additionally, the oligomers in the PO were mainly composed of dimers to pentamers. The secondary tandem MS/MS (MS2) experiments revealed that the m/z 360 is a dimer linked by coniferyl alcohol and a ferulate linkage, and no further fragmentation was observed in both the m/z 475 and 701 due to the rigidity of these structural motifs. [ABSTRACT FROM AUTHOR]

A four-year field trial was conducted in a rice paddy in southern China to determine the effects of continuous phosphate fertilizer, pig manure, chicken manure, and sewage sludge application on soil Cd accumulation in soil and Cd uptake by rice. The results showed that continuous application of fertilizers with higher Cd levels caused Cd to accumulate and redistribute in various soil fractions. In turn, these effects influenced Cd bioavailability in rice plants. After four years of phosphate fertilizer, pig manure, chicken manure, and sewage sludge application, the annual soil Cd accumulation rates were 0.007–0.032 mg kg −1 , 0.005–0.022 mg kg −1 , 0.002–0.013 mg kg −1 , and 0.032–0.087 mg kg −1 , respectively. Relative to the control, the pig- and chicken manure treatments significantly increased soil pH and reduced DTPA-extractable Cd (DTPA-Cd) and the exchangeable Cd fraction (Exc-Cd). In contrast, sewage sludge application significantly increased DTPA-Cd and Cd in all soil fractions. Phosphate fertilization had no significant effect on soil pH, DTPA-Cd, or Exc-Cd. Pearson's correlation coefficients showed that the rice grain Cd levels varied directly with DTPA-Cd, and Exc-Cd but inversely with soil pH. Pig- or chicken manure decreased rice grain Cd content, but sewage sludge increased both soil Cd availability and rice grain Cd uptake. Application of phosphate fertilizer had no significant effect on rice grain Cd content. The continuous use of organic- or phosphate fertilizer with elevated Cd content at high application rates may induce soil Cd accumulation and influence rice grain Cd accumulation. [ABSTRACT FROM AUTHOR]

Soil phosphorus (P) forms have been practically defined as chemically fractionated pools. A knowledge of the abundance and diversity of P forms in soil, and the factors affecting them, will lead to better soil management. However, little is known about the differences in P forms among soils with different geological properties in tropical Africa. The aim of this study was to investigate the P forms in soils with different physicochemical properties formed under different geological conditions in southern Tanzania and to identify the factors affecting the P forms in these soils. In total, 37 surface soil samples were collected from three geological groups; the plutonic (mainly granite) rock (PL) group, the sedimentary and metamorphic rock (SM) group, and the volcanic ash (V) group. Soil P was sequentially extracted by NH4Cl, NH4F, NaHCO3, NaOH + NaCl, and HCl, and inorganic (Pi) and organic P (Po) in each fraction were determined. The lowest total P was in the PL group (average, 360 mg P kg-1) because of the high sand content. Iron (Fe)-P (NaOH-Pi) was the major form in this group, accounting for 8.4% of total P. In the SM group (average total P, 860 mg P kg-1), Fe-P was the major form in most, accounting for 7.8% of total P. Soils in the SM group occasionally had high calcium (Ca)-P due to application of chemical fertilizer at the collection site. The V group had the highest total P (average, 1600 mg P kg-1) and its major P form was Ca-P, which was possibly derived from primary minerals (i.e., apatite), accounting for 14% of total P. In addition, the high oxalate-extractable Al possibly caused the accumulation of Al-P in the V group. Oxalate-extractable Fe generally increased with increasing Fe-Pi, while oxalate-extractable Al increased with increasing organic P and Al-Pi in soils in all three geological groups. These results demonstrate that the soil P forms differ greatly among sites in southern Tanzania with different geological conditions and associated soil properties. [ABSTRACT FROM AUTHOR]

Background and aims: The current paradigm for phosphorus (P) fertilizers applied to calcareous soil is that almost entirely water soluble P fertilizers are efficient and sparingly soluble P fertilizers are not efficient P sources for crops. We hypothesize that this paradigm does not apply to recycled P fertilizers and that other P pools can explain the plant use of recycled P fertilizers on calcareous soil.Methods: We applied 33P isotopic dilution method to evaluate recycled P fertilizers based on plant P uptake from fertilizer relative to plant uptake from a water soluble P reference fertilizer. The predictability of fertilizer effectiveness based on sequentially extracted P forms and X-ray diffraction pattern of recycled fertilizers derived from sewage sludge, human urine and organic waste was evaluated.Results: The plant experiments showed that tested recycled P fertilizers including compost were more effective than rock phosphate. The water insoluble P contained in urine based products was almost as effective as a fully water soluble P fertilizer. The tested recycled P fertilizers are characterized by complex P compounds differing in solubility which were so far not considered in the water and citric acid extraction methods. The fraction of resin- and NaHCO3 extractable fertilizer P explained effectiveness of P fertilizer applied to the calcareous and to an acidic soil.Conclusion: We concluded that water solubility is not required when P forms in recycled products are comparable to reactions products of rock phosphate based fertilizers in soil. Alternatives to fully water soluble P fertilizers are available to supply P to crops grown on calcareous soil efficiently. [ABSTRACT FROM AUTHOR]

Low availability of phosphorus (P) in Turkish soils is a significant problem of agricultural production depending on carbonates in slightly weathered and iron/aluminum oxides in highly weathered soils. Thus, crop-based P fertilization along with inherited nature of P partition can lead to changes in the amounts and geochemical fractions of phosphorus. For this reason, horizon-based surface samples were taken from 16 soil series that belong to four orders with different pedotransfer functions. The geochemical phosphorus fractions were sequentially extracted by sodium bicarbonate (NaHCO3), sodium hydroxide (NaOH), citrate-dithionite-bicarbonate buffer system (CBD), hydrochloric acid (HCl), and aqua-regia. Results indicated that weathering sequence was inversely related to plant available P fractions. The fertilizer P was possibly converted to HCl-extractable (Ca-Pi) fraction in calcareous soils through NaOH-Po and NaHCO3-Po fractions whereas it accumulated in the CBD-P fraction in relatively weathered soils. The carbonates and Al/Fe oxides were most significant constituents in P partitioning as consequences of parent material and weathering chronosequence. [ABSTRACT FROM PUBLISHER]

Interaction of Cu (II) ions with the matrix of soil and mineral phases of layered silicates was assessed by the Miller method of selective sequential fractionation and a set of synchrotron X-ray methods, including X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XANES). It was shown that the input of Cu into Calcic Chernozem in the form of monoxide (CuO) and salt (Cu(NO3)2) affected the transformation of Cu compounds and their affinity for metal-bearing phases. It was found that the contamination of soil with a soluble Cu(II) salt increased the bioavailability of the metal and the role of organic matter and Fe oxides in the fixation and retention of Cu. During the incubation of soil with Cu monoxide, the content of the metal in the residual fractions increased, which was related to the possible entry of Cu in the form of isomorphic impurities into silicates, as well as to the incomplete dissolution of exogenic compounds at the high level of their input into the soil. A mechanism for the structural transformation of minerals was revealed, which showed that ion exchange processes result in the sorption of Cu (II) ions from the saturated solution by active sites on the internal surface of the lattice of dioctahedral aluminosilicates. Surface hydroxyls at the octahedral aluminum atom play the main role. X-ray diagnostics revealed that excess Cu(II) ions are removed from the system due to the formation and precipitation of coarsely crystalline Cu(NO3)(OH)3. [ABSTRACT FROM AUTHOR]

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• 31P nuclear magnetic resonance spectroscopy was used on kettle hole sediments. • More calcium-bound phosphorus was determined in kettle hole sediments than in soils. • Kettle hole sediments contain more complex phosphomonoesters than arable soils. • Kettle hole sediments can lower the risk of leaching phosphorus to aquatic ecosystems. Phosphorus (P) is an essential element for all living organisms but can also be an important factor in the eutrophication of aquatic/marine ecosystems. Kettle holes are often situated in regions under intense agricultural land use where there is a high risk of nutrient transfer to larger waterbodies. The chemical speciation of soil P influences its rate of transfer from arable fields to aquatic environments. However, there is a paucity of information on the P speciation in kettle holes and their effect on the P cycle. Thus, we investigated the P composition of arable soils and kettle hole sediments in surface and subsurface layers along a transect of an agricultural field. Multiple P analyses were carried out including modified sequential Hedley P fractionation, P K -edge X-ray absorption near edge structure (XANES) spectroscopy, and 31P nuclear magnetic resonance (NMR) spectroscopy. The P t concentrations ranged from 680 to 1123 mg kg−1 in the soils and 797 to 2591 mg kg−1 in the sediments. A predominance of the residual-P fraction, characterized as not extractable P, occluded P or stable forms of organic P (P o) was determined by sequential fractionation, ranging from 37 to 67 % followed by 3 to 38 % H 2 SO 4 -P i and 3 to 16 % NaOH-P o of total P (P t) in the soils and sediments. Analyses with P K –edge XANES spectroscopy assigned 61 to 100 % Fe- and Al-P, 0 to 14 % Ca-P, and 0 to 39 % P o in the arable soils and 46 to 74 % Fe- and Al-P, 14 to 43 % Ca-P, and 0 – 38 % P o in the adjoining kettle hole sediments. Solution 31P NMR spectra on alkaline extracts revealed a broad signal in the phosphomonoester region, which was the most abundant form of organic P across all samples. Besides, the proportion of 'complex' phosphomonesters (broad signal) to that of total extractable P was about 2-fold greater in the kettle hole sediments than in soils. Complex forms of organic P are known to be strongly associated with organic matter (OM) and appear to accumulate on a decadel timeframe. Therefore, it is desirable that kettle hole sediments are conserving P (and carbon), which will help reduce the transfer of P from agricultural fields to other, more vulnerable aquatic/marine ecosystems. [ABSTRACT FROM AUTHOR]

Purpose: The study is aimed at the analysis of the spatial-structural organization of Pb(II) in Chernozem soils and the relationship between the metal ion and the soil components using X-ray absorption spectroscopy and chemical extractive fractionation. Materials and methods: In a model experiment, soil samples were artificially contaminated with elevated rates of Pb(NO) and PbO (2000 and 10,000 mg kg). The samples of mineral phases (bentonite, gibbsite, kaolinite, calcite, and hydromuscovite) were saturated with Pb ions. The sequential fractionation of Pb in the soil was conducted by the Tessier method. X-ray absorption near-edge fine structure (XANES) spectra at the Pb L-edge (13.040 keV) were obtained on a Rigaku R-XAS Looper spectrometer. Extended X-ray absorption fine structure (EXAFS) L-edge Pb was measured at the Structural Materials Science beamline of the Kurchatov Center for Synchrotron Radiation. Results and discussion: The results of successive extraction showed that Pb is associated with strongly bound organic substances, Fe and Mn (hydr)oxides, and carbonates. An increase in the portion of exchangeable fraction is observed under extreme loads. At the addition of Pb in the form of oxide and nitrate to the soil, the fractional compositions were similar, which indicates the good transformation of PbO in Chernozem. The features of XANES spectra indicate different orbital transitions in the electron shells of Pb ions for monoxide (PbO) and soluble salt (Pb(NO)), which affect the ion properties and determine the individual structure of the coordination sphere. The analysis of XANES revealed that sorption of Pb in the soil samples and in the samples of mineral phases does not change its bond valence. Conclusions: The increased degree of soil contamination with Pb is accompanied by decreasing the stable connection between metal and soil components. Lead ions in bentonite, kaolinite, hydromuscovite, gibbsite, and calcite are incorporated in the positions of the inner-sphere complex replacing some aluminum ions in the octahedral sites. This results in changes the Pb-O distances in Pb-bearing octahedrons. We may suggest that Pb is also sorbed by dimer (Pb-Pb) silicate and/or aluminum groups. The structure of adsorbent surface plays the key role in the sorption of Pb by mineral phases. [ABSTRACT FROM AUTHOR]

One of the bottlenecks to efficient phosphorus (P) recycling is limited understanding of the relationships between inorganic P species in waste products and their P fertilisation effects. In this study, we characterised inorganic P species in seven waste products (two biomass ashes, meat bone meal, fish sludge, catering waste and two food waste-based digestate products) and two manure products (dairy and chicken manure) by: (1) Sequential chemical fractionation, (2) X-ray powder diffraction and (3) solid-state P MAS-NMR spectroscopy. We then used the characterisation data to explain the results of a bioassay studying the fertilisation effects of waste and manure products after application to a nutrient-deficient model soil that was limed to two pH levels (approximately pH 5.5 and 6.9 at pH level 1 and 2), with ryegrass ( Lolium multiflorum) as the experimental crop. The P in waste products was mainly present as a complex mixture of inorganic P species, predominantly Ca phosphates with differing solubility. Fertilisation effects were largely explained by sequential fractionation data, with a positive relationship between apparent P use efficiency and the HO-soluble inorganic P fraction at pH level 1 (R = 0.52) and a negative relationship between apparent P use efficiency and the HCl-soluble inorganic P fraction at pH level 2 (R = 0.66). X-ray powder diffraction and solid-state P MAS-NMR spectroscopy confirmed the sequential fractionation data, but provided little additional information. [ABSTRACT FROM AUTHOR]

A caracterização dos diversos compartimentos de P, além de avaliar frações não monitoradas regularmente pelos métodos de diagnose da fertilidade do solo, pode favorecer o entendimento do ciclo desse nutriente. O objetivo deste trabalho foi avaliar as alterações nos compartimentos de P de um Cambissolo Háplico Ta eutrófico vértico, cultivado com cana-de-açúcar por longo tempo. Em uma das áreas de estudo, não foi realizada a despalha da cana utilizando fogo por ocasião da colheita durante 55 anos. Em outra área, realizou-se a queima do canavial, mas, durante 35 anos, foram aplicados, via irrigação por aspersão, 120 m³ ha-1 ano-1 de vinhaça. Em duas áreas adjacentes a ambos os locais, foram coletadas amostras para efeito de comparação. As amostras foram coletadas em duas camadas (0-0,20 e 0,20-0,40 m) e analisadas por meio de um procedimento de extração seqüencial de P. Foram determinados também os teores de P total, P disponível, P orgânico, P inorgânico e P nas substâncias húmicas. Os resultados deste trabalho indicam que o manejo da cana crua possibilitou maior conteúdo de P em todos os compartimentos analisados. A manutenção da palha e a adição de vinhaça alteraram a distribuição das frações de P no solo, com diminuição da participação das formas não-lábeis e conseqüente aumento das formas lábeis. Em todos os manejos observados, o teor de P no ácido húmico foi maior que no ácido fúlvico. O menor teor de P orgânico na cana crua evidenciou a participação desse componente na disponibilidade de P por meio de sua mineralização.The characterization of several soil phosphorus (P) pools allowed the evaluation of P components not usually monitored in fertilizer soil tests and can help to understand this nutrient's cycle. The aim of this study was to evaluate the changes in P pools of a Fluventic Eutrochrepts fine clay which had been under long-time sugarcane plantation. In one situation the sugarcane had been cropped for 55 years with and without trash burning prior to harvesting. The other sugarcane plantation, cultivated for 35 years, with crop residues and leaves burning, had received annual stillage inputs through aspersion irrigation at rates of 120 m³ ha-1 yr-1. Soil samples were taken from the 0-0.20 and 0.20-0.40 m layers and a sequential P fractionation method was performed. Total P, available P, organic P, inorganic P and P in humic substances were also evaluated. The results of this study indicated that the management with trash preservation on the soil surface promoted higher P content in all evaluated pools. The preservation of crop residues and leaves and stillage addition modified the P pool distribution, promoting a decrease of non-labile pools and consequently an increase of labile pools. At all studied sites the P content was higher in the humic than in the fulvic acid fraction. The smallest relative participation of organic pools at the site without burning suggests the contribution of this pool to the available P through its mineralization.