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Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phosphorus (P) forms in sediments can be affected by various environmental factors, and P transformation in the water-sediment interface contributes to the eutrophication of water bodies. Therefore, a series of methods have been proposed to extract P forms in sediments. In order to explore the progress and research hotspots of P form analysis of sediments using different extraction methods, the core collection of Web of Science is taking as data source, and the CiteSpace knowledge map analysis tool is used to carry out visual analysis from the aspects of publication output, country analysis, publishing institution analysis, keyword analysis, literature co-citation analysis, burst terms analysis, and cluster analysis. The literature on the extraction methods for P form analysis of sediments was found to have boomed from 2013 to 2022, with higher contributions from China, France and United States. The cluster analysis of keywords and co-citation clarified the main research frontiers and hotspots. The bioavailability, migration and transformation mechanisms of P forms will become a new hotspot in this field in the future. [ABSTRACT FROM AUTHOR]

Understanding soil phosphorus (P) distribution and its key drivers is fundamental for sustainable P management. In this study, a 21-year fertilization experiment on black soil was carried out, setting up five fertilization treatments: unfertilized control (CK), nitrogen and potassium (NK), nitrogen, P and potassium (NPK), NPK plus straw (NPKS), and NPK plus manure (NPKM). The distribution and effecting factors of P pools within soil aggregates were investigated. Compared to CK, the NK and NPK treatments decreased calcium-associated P concentration in all aggregate fractions. Meanwhile, the NPK treatment significantly increased the organic P extracted from NaOH in unaggregated particles (<0.053 mm). This was mainly due to the reduction in soil pH. The NPKS and NPKM treatments increased almost all P forms in aggregates, especially Ca-P. For the NPKM treatment, inorganic P extracted from resin, NaHCO3, and NaOH increased as aggregate size increased. This was mainly because straw or manure addition promoted soil organic carbon (SOC) storage in aggregates, creating more sorption sites via association with amorphous metallic minerals, and, thus, facilitating P accumulation. In conclusion, decreasing soil pH by chemical fertilizers is an effective strategy for mobilizing soil P, whereas increasing SOC by straw or manure facilitates P accumulation. [ABSTRACT FROM AUTHOR]

The study of the fractions and distribution characteristics of organic phosphorus in the sediment of the water level fluctuating zone of Nansi Lake is conducive to revealing the transformation of phosphorus in the lake, and has important scientific significance for controlling the eutrophication of Nansi Lake. Based on the sediment of the water level fluctuation zone of Nansi Lake. The improved Hedley continuous grading extraction, ultraviolet-visible spectroscopy and three-dimensional fluorescence spectroscope were used to characterize the structural characteristics and stability of organic molecules in the sediment, and to reflect the differences in the structure and stability of organophosphate in the water level fluctuating zone. Principal component analysis (PCA), Redundancy analysis (RDA) and correlation heat map analysis were used to analyze the correlation between phosphorus and physicochemical index. The results showed that the alternation between wet-dry conditions was more favorable for the release of phosphorus from sediment, compared to continuous inundation conditions. Moreover, the higher the frequency of wet-dry alternations, the greater the release of phosphorus in different forms from the sediment. Wet-dry alternation resulted in a reduction of substituent on the aromatic rings of sediment DOM (dissolved organic matter), and the continuous drying would increase the molecular weight and humidification degree of DOM in the sediment. Correlation analysis showed that NaOH-Po content in sediment was significantly negatively correlated with TP, IP, OP and various organophosphorus forms, indicating a close transformation relationship between phosphorus forms in sediment. The results can provide a scientific basis for controlling the release of endogenous phosphorus and the risk of eutrophication in Nansi Lake.

This study aims to understand the characteristics and distribution patterns of soil phosphorus (P) forms in the tropical high‐P orchards under cover cropping and to explore the biotic and abiotic factors driving the changes in P forms. The study collected three kinds of soil (clean tillage [CK, control], Stylosanthes guianensis cover [SC, legume], and Cynodon dactylon (L.) Pers. cover [CC, grass]) from a mango orchard and determined P forms in the water‐stable aggregates and bulk soil, analyzed the environmental factors and the structure of the bacterial‐fungal community. Compared to CK, SC and CC have a significant positive influence on the forms and distribution of soil P, increase the content of organic P (Org‐P) and certain inorganic P forms (Al‐P and Fe‐P), and enhance the content of P within macroaggregates (>0.25 mm), thereby maintaining total P (TP) and Olsen‐P in the top 30 cm of soil, particularly for the SC treatment. SC and CC also improved acid phosphatase (ACP), and water‐stable aggregates while decreasing bulk density (BD) and exchangeable aluminium (Ale) in the topsoil (0–15 cm). Redundant and Pearson analysis revealed these factors significantly affected soil P availability. Moreover, SC and CC increased the relative abundance of Nitrospira, Candidatus‐Udaeobacter, Pseudolabrys, and ADurb.Bin063–1 in the topsoil (0–15 cm), and decreased the relative abundance of Occallatibacter. Redundant and Pearson analysis indicated that these bacterial communities are likely associated with the availability of P. Overall, cover cropping promoted the transformation and distribution of P forms by altering the physical, chemical, and biological environment of the soil, which was beneficial for the sustainable P management in tropical high‐P soils. This research offers practical insights into the use of cover crops as a tool for enhancing soil health and sustainable P management in tropical high‐P orchards. [ABSTRACT FROM AUTHOR]

With the continuous improvement of surface water environmental quality in China, sediment has gradually become the focus of research on internal pollution in reservoirs. To investigate the forms, distribution, and migration patterns of phosphorus in karst canyon reservoir sediments, we employed an improved sequential graded extraction method to determine phosphorus content in the sediments of the Wanfeng Reservoir. We studied the spatial distribution characteristics and release risk of phosphorus form in the sediments. The results showed that the total phosphorus (TP) content ranged from 79.37 to 438.04 mg·kg−1, while inorganic phosphorus (IP) content ranged from 77.32 to 424.64 mg·kg−1. Iron–aluminum-bound inorganic phosphorus (Fe/Al-Pi) accounted for 36.41% and was found to be the dominant form of IP. Organic phosphorus (OP) content ranged from 1.84 to 13.59 mg·kg−1, with weakly adsorbed organic phosphorus (H2O-Po) being the dominant form of OP. Potentially active inorganic phosphorus (NaHCO3-Pi) showed a highly significant positive correlation (p < 0.01) with Fe/Al-Pi, residual phosphorus (Res-P), and TP. This indicates that potentially active phosphorus (NaHCO3-P) is a significant potential source of phosphorus (P) in the reservoir. Biologically active phosphorus (BAP) content ranged from 66.97 to 201.46 mg·kg−1, with BAP/TP ratios ranging from 55.6% to 59.6%. The risk of phosphorus release from Wanfeng Reservoir sediments is high. The release of various forms of phosphorus from sediments is one of the important factors leading to the deterioration of water quality in the reservoir area in the future. To effectively manage water ecology in karst canyon reservoirs, it is essential to reduce the risk of endogenous phosphorus release. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil phosphorus (P) is a vital nutrient that controls wetland productivity and ecological functions. However, the effects of soil P forms on P availability during wetland degradation are relatively unknown. We selected differently degraded marshes, including non‐degraded marsh (NDM), lightly degraded marsh (LDM), moderately degraded marsh (MDM), and heavily degraded marsh (HDM), to research the changes in soil P forms by sequential chemical extraction and its regulation on P availability in the Zoige Plateau, China. The results showed that compared with the 0–30 cm soil layers of NDM, the main changes in total P concentration were a significant increase of 31.6%–44.2% in LDM and MDM, and the available P concentration increased by 28.7%–76.2% in LDM and MDM but decreased by 4.0%–47.5% in HDM with a lower P activation coefficient. Marsh degradation increased the concentration of soil dicalcium phosphates, P occluded in iron hydroxides, and organic P from the entire profile by 46.7%–137.7%, 31.7%–49.3%, and 78.1%–82.1%, respectively, while it decreased that of iron oxide surface adsorbed P and apatite P by 17.2%–32.2% and 15.3%–27.8%, respectively. Soil available P was mainly related to organic P and P non‐occluded in iron oxide minerals, which might also be a non‐negligible direct source of available P. The transformation from apatite P to organic P was an important regulatory mechanism of P availability in soils during marsh degradation. This study revealed the transformation trajectory of soil P forms owing to soil desiccation accompanied by plant community changes and overgrazing during alpine marsh degradation, and the risk of P limitation in HDMs with low soil available P. For degraded marsh restoration, some measures for improving P availability should be implemented in the future, such as grazing exclusion and the application of organic fertilizer. [ABSTRACT FROM AUTHOR]

To investigate the influence of nitrogen (N) and phosphorus (P) availability on the periphytic algal biomass and assemblage composition (by pigment analysis) in the eutrophic lake, natural littoral intact sediment cores in a subtropical eutrophic lake (Lake Taihu) were collected, and subjected to three levels of water N and P loading (N-P [mg. L−1]: 1.5, 0.075; 2.5, 0.125; 3.5, 0.175) in the tanks, eighteen artificial substances (glass slides) were fixed at three water depths (1, 17, and 33 cm above the surface sediment) for development of periphytic algae in each tank, respectively. The results showed that the biomass of periphytic algae on artificial substance was significantly enhanced with increasing N and P levels in water column and water depth (p < 0.05), while sediment-associated periphytic algae did not significantly increase with increasing N and P levels in water column. The development of sediment-associated periphytic algae changed the phosphorus form, calcium-bound phosphorus and inorganic phosphorus in the sediments decreased slightly, and the total phosphorus and organic phosphorus in the sediments increased. Our results suggest that N and P availability is conducive to the development of periphytic algae in subtropical eutrophic shallow lakes in spring. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phosphorus (P) is an essential nutrient for phytoplankton growth in water bodies and an important element in biochemical processes. Also, excessive P in river causes eutrophication which endangers aquatic organisms while sediment acts as sink for inorganic and organic pollutants and nutrients. To assess the availability of P and heavy metals (HMs) in Ogun River, surface sediment samples were collected at twelve anthropogenic sites for three months. The surface sediment samples were sequentially extracted to determine five phosphorus fractions [loosely-sorbed P (LS-P), iron-bound P (Fe-P), authigenic apatite, biogenic apatite and CaCO3-bound P (CFA-P), detrital apatite (Det-P) and other inorganic P (IP) as well as organic P (OP)] and levels of selected HMs (Pb, Cr and Zn). Phosphorus fractions were determined spectrophotometrically and HMs were determined using atomic absorption spectrophotometer (AAS) after wet digestion. The average percentages of fractions of P in surface sediments were Det-P (34.66±1.00%) > Fe-P (27.67± 0.02%) > OP (18.11±2.00%) > authigenic apatite, biogenic apatite and CaCO3-bound P (14.38±4.56%) > LS-P (5.18±0.78%). It was observed that IP was dominant (86.38%) of the total phosphorus (TP) compared to OP (13.62%). One of the sites, Garri processing, had highest TP (710 µg P g-1) which was above the standard values for Chinese Environmental Dredging (500 µg P g-1) and Canadian Province of Ontario (600 µg P g-1) Sediment Quality Guidelines (SQG). The mean concentrations of HMs determined in sediments were below the SQG values except Zn in some sites. The results revealed moderate pollution of P and Zn and also, accumulation of these pollutants overtime might pose threat to aquatic organisms. The results obtained would serve as baseline values for P speciation in Ogun River.

The easy fixation of phosphorus fertilizer in soil is a main reason for the low utilization rate of phosphorus fertilizer. In order to study the effects of fertilization frequency on availability of phosphorus fertilizer, three cinnamon soils with different Olsen-P levels (19.4, 24.2, 49.7 mg·kg-1) were collected in the long-term fertilization test based on Shouyang County, Jinzhong City Shanxi Province, and the same amount of phosphorus fertilizer (potassium dihydrogen phosphate) was added to the soil with different Olsen-P levels by once and 3 times, respectively. The soil with Olsen-P was incubated under constant temperature condition for 90 d, soil Olsen-P content was measured by 11 sampling intervals, and the phosphorus forms in soil were measured at the end of incubation. The effects of fertilization frequency on soil Olsen-P content, phosphorus fixation rate and phosphorus forms were analyzed, and characteristics on availability of phosphorus fertilizer under different fertilization times were clarified. The results showed that after 90 d of fertilization, the soil Olsen-P contents under 3 times of application increased significantly compared with that of once of application, and the increase rates at 3 Olsen-P levels were 21.0%, 13.5% and 9.4%, respectively. However, the phosphorus fixation rate decreased significantly, which were 8.0%, 6.8% and 10.5% at 3 Olsen-P levels, respectively. The Michaelis-Menten equation betterly fitted the process of soil phosphorus fixation. The maximum phosphorus fixation rate of once application was greater than that of 3 times application, but the time to reach 50% of the maximum phosphorus fixation rate was shorter than that of 3 times application. The phosphorus fixation rate decreased with the increase of Olsen-P levers under once application. Phosphorus fixation rate in high Olsen-P (49.7 mg·kg-1) soil was significantly reduced by 10.8%~ 12.4% compared with low Olsen-P (19.4~24.2 mg·kg-1) soil under 3 times application.When compared with once application, the content of labile P in soil increased by 6.8%~12.1%, and the content of non labile P decreased by 8.4% under 3 times application. This study showed that the 3 times application of phosphorus fertilizer could significantly improve the availability of soil phosphorus and reduce the fixation rate of phosphorus fertilizer; the higher soil Olsen-P content was, the smaller the proportion of phosphorus fertilizer was invalidated in soil; the 3 times application of phosphorus fertilizer could increase soil Olsen-P content, decrease phosphorus fixation rate and increase the content of labile P. These results had important directive significance to improve the utilization rate of phosphorus fertilizer, and provided theoretical basis for efficient and scientific application of phosphorus fertilizer. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 32-year fertilizer experiment was conducted to investigate mineral and organic fertilization impacts on soil P forms by P K-edge X-ray absorption near edge structure and solution 31P nuclear magnetic resonance spectroscopy. The experiment included six treatments: control without fertilization, mineral fertilizers (NPK), pig manure at 30,000 (M1) and 60,000 kg ha–1 (M2), M1 plus NPK, and M2 plus NPK. The predominant P compounds were hydroxyapatite (up to 51.3% of soil total P) and orthophosphate and orthophosphate monoesters (up to 85.7% and 57.0% of soil NaOH-EDTA extractable total P, respectively). Compared with the control, the concentrations and proportions of monocalcium phosphate and orthophosphate increased following mineral fertilizers alone. Manure application, especially high rate manure combined with mineral fertilizers, further increased the concentrations and proportions of monocalcium phosphate and orthophosphate relative to mineral fertilizers alone. Moreover, manure amendment also generally increased the concentrations of other inorganic and organic P compounds. Manure application improve soil P availability by adding high concentrations of bioavailable inorganic P compounds to soil, similar to the addition of mineral fertilizers. This study contributes to the understanding of applied fertilizers and residual soil P dynamics and provides insights for sustainable P management in agricultural ecosystems. [ABSTRACT FROM AUTHOR]

The horizontal distributions of total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) in the surface sediments where complex aquaculture is conducted in Shido Bay, Seto Inland Sea, Japan, were determined to investigate the impact of fish and oyster farming. We also determined five fractions of phosphorus in the surface sediments. Relatively high phosphorus contents (P/C ratios) were observed in fish farming areas, likely due to the waste feed and fecal matter. Moreover, relatively high abundances of the Ca-bound P (Ca-P) and detrital P (Ref-P) fractions were observed in fish farming areas, likely due to bones of small fish used as feed. Our results strongly suggest that the P/C ratio and the Ca-P and Ref-P fractions in the surface sediments are good indicators of the effects of fish farming and allow its characterization, and are particularly valuable in the area of complex aquaculture. [ABSTRACT FROM AUTHOR]

Understanding soil phosphorus (P) distribution and its key drivers is fundamental for sustainable P management. In this study, a 21-year fertilization experiment on black soil was carried out, setting up five fertilization treatments: unfertilized control (CK), nitrogen and potassium (NK), nitrogen, P and potassium (NPK), NPK plus straw (NPKS), and NPK plus manure (NPKM). The distribution and effecting factors of P pools within soil aggregates were investigated. Compared to CK, the NK and NPK treatments decreased calcium-associated P concentration in all aggregate fractions. Meanwhile, the NPK treatment significantly increased the organic P extracted from NaOH in unaggregated particles (3, and NaOH increased as aggregate size increased. This was mainly because straw or manure addition promoted soil organic carbon (SOC) storage in aggregates, creating more sorption sites via association with amorphous metallic minerals, and, thus, facilitating P accumulation. In conclusion, decreasing soil pH by chemical fertilizers is an effective strategy for mobilizing soil P, whereas increasing SOC by straw or manure facilitates P accumulation.

With the continuous improvement of surface water environmental quality in China, sediment has gradually become the focus of research on internal pollution in reservoirs. To investigate the forms, distribution, and migration patterns of phosphorus in karst canyon reservoir sediments, we employed an improved sequential graded extraction method to determine phosphorus content in the sediments of the Wanfeng Reservoir. We studied the spatial distribution characteristics and release risk of phosphorus form in the sediments. The results showed that the total phosphorus (TP) content ranged from 79.37 to 438.04 mg·kg−1, while inorganic phosphorus (IP) content ranged from 77.32 to 424.64 mg·kg−1. Iron–aluminum-bound inorganic phosphorus (Fe/Al-Pi) accounted for 36.41% and was found to be the dominant form of IP. Organic phosphorus (OP) content ranged from 1.84 to 13.59 mg·kg−1, with weakly adsorbed organic phosphorus (H2O-Po) being the dominant form of OP. Potentially active inorganic phosphorus (NaHCO3-Pi) showed a highly significant positive correlation (p < 0.01) with Fe/Al-Pi, residual phosphorus (Res-P), and TP. This indicates that potentially active phosphorus (NaHCO3-P) is a significant potential source of phosphorus (P) in the reservoir. Biologically active phosphorus (BAP) content ranged from 66.97 to 201.46 mg·kg−1, with BAP/TP ratios ranging from 55.6% to 59.6%. The risk of phosphorus release from Wanfeng Reservoir sediments is high. The release of various forms of phosphorus from sediments is one of the important factors leading to the deterioration of water quality in the reservoir area in the future. To effectively manage water ecology in karst canyon reservoirs, it is essential to reduce the risk of endogenous phosphorus release.

Straw returning is an effective practice for improving soil quality and increasing soil nutrients. However, the effect of straw returning on soil phosphate fractions and phosphate-solubilizing microorganisms (PSM) needs to be clarified. Here, we studied the variation of soil properties, soil phosphate fractions, and microbial communities at 0–40 cm soil layer under four treatments (S0 (0 kg/ha straw), S1 (3000 kg/ha straw), S2 (6000 kg/ha straw), and S3 (9000 kg/ha straw)). Soil properties were measured by conventional methods; soil phosphate fractions were measured by the Bowman-Cole method, and soil microbial communities were determined by high-throughput sequencing. The results showed that total phosphorus (TP), total organic phosphorus (TOP), and total inorganic phosphorus (TIP) increased by 16.16–59.52, 53–73.4, and 18.7–45.54% in S1, S2, and S3 compared to S0. The Chao1 (community richness) and Shannon (community diversity) index of bacteria and fungi were significantly higher in S1, S2, and S3 treatments than in S0. Redundancy analysis (RDA) results showed that the contribution of TOP, TIP, and soil organic matter (SOM) to the relative abundance of microbes were 84.20–94.80, 83.20–94.40, and 89.20–94.10%, respectively, which was significantly higher than that of other soil variables (field moisture capacity (FMC), soil porosity (SP), soil bulk density (SBD), pH, electrical conductivity (EC), cation exchange capacity (CEC), residual phosphorus (RP), TP, available phosphorus (AP)). Overall, long-term straw returning can alter the soil phosphate fractions by improving TOP, TIP, and SOM contents, thus effectively enhancing the abundance of soil microorganisms in 0–40 cm soil, especially the abundance of PSM in the surface soil. [ABSTRACT FROM AUTHOR]

Soil phosphorus (P) can be divided into inorganic P (Pi) and organic P (Po). Microorganisms play essential roles in soil P transformation. However, there are many ways to detect P transformation, and the relationship between P forms and microorganisms under long-term fertilization is largely unclear. In this study, soil P forms were analyzed by a chemical sequential fractionation method and solution 31P nuclear magnetic resonance (31P-NMR) technique. Phospholipid fatty acid (PLFA) contents were measured by gas chromatography as the characterization of soil microbial community structures. The objective was to determine the changes of soil P forms and associated microbial community composition in mollisol with long-term fertilization. We sampled soil from a field experiment with 26-year-old continuous maize (Zea mays L.) cropping in Northeastern China. Three fertilization treatments were selected as chemical fertilization (NPK), NPK with crop straw (NPKS), and NPK with manure (NPKM). As shown in 31P-NMR spectra, orthophosphate accounted for 62.8–85.8% of total extract P. Comparison to NPK and NPKS treatments, NPKM application notably increased the concentrations of Po, Olsen-P, orthophosphate, orthophosphate monoester, and total P. Soil P fractions including resin-Pi, NaHCO3-P, NaOH-P, and HCl-P, especially Pi fractions, were enhanced by NPKM. The amounts of total PLFAs and PLFAs in bacteria, Gram-positive (G+) and Gram-negative (G−) bacteria, actinomycetes, and fungi were high in NPKM-treated soil. The percentages of PLFAs in bacteria and fungi in total soil PLFAs were 56.8% and 9.7%, respectively, which did not show any significant difference among the treatments. NPKM increased the proportions (%) of PLFAs in G+ bacteria, and NPKS increased the proportions (%) of G− bacteria in total PLFAs. The composition of soil microbial community was found to be significantly affected by soil total carbon and pH. There was a close relationship between HCl-Pi, NaHCO3-Po, orthophosphate, and pyrophosphate with anaerobe, aerobes, and G+. Manure addition directly increased soil available P concentrations, and indirectly acted through the alterations of anaerobe, aerobes, and G+. It is concluded that long-term NPKM application would lead to the accumulation of labile P and moderately labile P in mollisol through the activity of soil microbes. [ABSTRACT FROM AUTHOR]

Phosphorus (P) in sediments plays an important role in shallow lake ecosystems and has a major effect on the lake environment. The mobility and bioavailability of P primarily depend on the contents of different P forms, which in turn depend on the sedimentary environment. Here, sediment samples from Baiyangdian (BYD) lake were collected and measured by the Standards, Measurements, and Testing procedure and Phosphorus-31 nuclear magnetic resonance spectroscopy (31P NMR) to characterize different P forms and their relationships with sediment physicochemical properties. The P content in the sediments varied in different areas and had characteristics indicative of exogenous river input. Inorganic P (334–916 mg/kg) was the dominant form of P. The 31P NMR results demonstrated that orthophosphate monoesters (16–110 mg/kg), which may be a source of P when redox conditions change, was the dominant form of organic P (20–305 mg/kg). The distribution of P forms in each region varied greatly because of the effects of anthropogenic activities, and the regions affected by exogenous river input had a higher content of P and a higher risk of P release. Principal component analysis indicated that P bound to Fe, Al, and Mn oxides and hydroxides (NaOH-P) and organic P were mainly derived from industrial and agricultural pollution, respectively. Redundancy analysis indicated that increases in pH lead to the release of NaOH-P. Organic matter plays an important role in the organic P biogeochemical cycle, as it acts as a sink and source of organic P. [Display omitted]. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: The dynamics of phosphorus in lake sediment have received much attention due to their potential to trigger eutrophication. This study was aimed to reveal the distribution pattern of phosphorus forms, total nitrogen (TN), and total organic carbon (TOC), estimate the contributions of different phosphorus forms to total phosphorus, and evaluate the ecological risks of nitrogen and phosphorus pollution in the sediments from Daye Lake, Central China. Method: Thirty-nine surface sediment samples were collected in the dry season. TOC and TN were analyzed by an elemental analyzer. Phosphorus forms were determined based on the European standard SMT (Standard Measurements and Testing) method. The integrated pollution index method was used to assess the TN and TP pollution levels of sediment. The relationships between different phosphorus forms and TOC and TN in sediments were also discussed. Result and discussion: TOC, TN, and TP contents in the sediments of Daye Lake were 0.96–6.15%, 859.8–5562.533 mg kg−1, and 973.06–7982.86 mg kg−1, respectively. The average contents of phosphorus in various forms were IP (1605.24 mg kg−1) > Ca-P (1093.39 mg kg−1) > OP (897.49 mg kg−1) > Fe/Al-P (523.79 mg kg−1). The contents of different phosphorus forms showed certain spatial differences due to the impact of human activities, agricultural, and industrial production. IP was the most important form of phosphorus in sediments, accounting for 49 ~ 63% of TP. TOC/TN ratio in the sediments ranged from 7.23 to 11.35, indicating that endogenous pollution was the main source. The results of TN and TP pollution in the surface sediments of Daye Lake evaluated by single pollution standard index method showed that the standard index of the TN (STN) ranged from 0.86 to 5.56 and the standard index of the TP (STP) ranged from 1.62 to 13.30. It indicated that N and P in sediments of Daye Lake were seriously polluted, and there was a potential risk of endogenous pollutant release which may further aggravate the eutrophication of water body. Conclusion: The distribution of TN, TP, and TOC in the sediments showed a gradual decreasing trend from the downstream to the upstream in Daye Lake. TP in the sediments mainly existed in the form of IP. IP content was mainly influenced by Fe/Al-P and Ca-P. The ecological risk of nitrogen and phosphorous in the sediments was serious, and the water body was threatened by eutrophication. [ABSTRACT FROM AUTHOR]

The pH value of lake water varies with the lake environment, which has an effect on the form of phosphorus in sediment, and then the release of sediment phosphorus. The form of phosphorus in sediments was analyzed using field sampling. The environmental conditions with pH values of 4.0, 7.0 and 10.0 were simulated indoors to estimate the effects of pH on phosphorus release from sediments and the content change of various forms of phosphorus was studied. The results showed that in Wuliangsuhai Lake, Ca-P accounted for 54.3%, which was the largest portion of the TP. Phosphorus release was favored under acidic and alkaline conditions, and the alkaline condition was more favorable. The proportion of Fe/Mn-P and Fe/Al-P in the TP decreased with an increase in the pH, while the proportion of Ca-P in the TP increased with an increase in the pH. Under the alkaline condition (pH = 10), Ca-P in the sediment increased significantly, with an increase of 22.5%. However, Fe/Mn-P and Fe/Al-P decreased significantly, with drops of 37.3% and 44.9%, respectively. Under the acidic condition (pH = 4), Fe/Mn-P and Fe/Al-P in the sediment increased significantly, and the increases were 63.1% and 37.1%, respectively. However, Ca-P decreased significantly, with a drop of 39.2%. In general, low pH promoted the release of Ca-P, and a high pH promoted the release of Fe/Mn-P and Fe/Al-P. Wuliangsuhai Lake water is characterized by weak alkaline characteristics throughout the year, and biological available phosphorus accounts for 13.3%–20.9% of the TP, with Fe/Mn-P being the dominant form. This study revealed that the risk of phosphorus release from sediments to the overlying water was greater under alkaline conditions. HIGHLIGHTS Evaluate the effect of pH change on different phosphorus forms content in sediments of lake.; Determine phosphorus forms and the effects of pH on their fraction transformation based on indoor simulation experiments.; To explore which part of phosphorus form was affected by pH change, and which resulted in the change of phosphorus content in sediments, which is the focus of this study.;

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The phosphorus (P) leaching from continuous fertilization is generally neglected in mollisol. The in situ leaching loss of phosphorus (P), especially dissolved organic P, is poorly quantified under organic amendments given its potential environmental risks. In this study, we conducted an in situ soil column experiment, instead of the traditional measuring of the soil layer, in the mollisol area of northeast China to investigate the seasonal variations in different P forms under three typical fertilization practices, including chemical fertilizer (CF), CF supplemented with straw (CFS), and CF co-applied with straw and manure (CFSM). Compared with the CF treatment, CFS treatment generally reduced the leaching loss of dissolved organic P by 57.3% to reduce the total P loss, while the CFSM treatment increased the leaching loss of dissolved inorganic P by 20.9% to increase the total P loss. Other than the effects of management practices, precipitation and temperature-oriented environmental factors significantly affected the seasonal variation in leaching loss of both the dissolved and particulate P forms. We conclude that straw incorporation into the mollisol of northeast China is recommended, considering its low leaching risk of P, while a co-amendment of straw and manure resulted in the opposite. Despite the slight environmental risk of P leaching loss (0.75–1.95% of external P input per year) practically quantified by in situ experiments, a proper reduction in chemical P input with organic amendments may be an effective P fertilizer management strategy in mollisol areas. [ABSTRACT FROM AUTHOR]

The study of the fractions and distribution characteristics of organic phosphorus in the sediment of the water level fluctuating zone of Nansi Lake is conducive to revealing the transformation of phosphorus in the lake, and has important scientific significance for controlling the eutrophication of Nansi Lake. Based on the sediment of the water level fluctuation zone of Nansi Lake. The improved Hedley continuous grading extraction, ultraviolet-visible spectroscopy and three-dimensional fluorescence spectroscope were used to characterize the structural characteristics and stability of organic molecules in the sediment, and to reflect the differences in the structure and stability of organophosphate in the water level fluctuating zone. Principal component analysis (PCA), Redundancy analysis (RDA) and correlation heat map analysis were used to analyze the correlation between phosphorus and physicochemical index. The results showed that the alternation between wet-dry conditions was more favorable for the release of phosphorus from sediment, compared to continuous inundation conditions. Moreover, the higher the frequency of wet-dry alternations, the greater the release of phosphorus in different forms from the sediment. Wet-dry alternation resulted in a reduction of substituent on the aromatic rings of sediment DOM (dissolved organic matter), and the continuous drying would increase the molecular weight and humidification degree of DOM in the sediment. Correlation analysis showed that NaOH-P o content in sediment was significantly negatively correlated with TP, IP, OP and various organophosphorus forms, indicating a close transformation relationship between phosphorus forms in sediment. The results can provide a scientific basis for controlling the release of endogenous phosphorus and the risk of eutrophication in Nansi Lake. • Fractions and distribution characteristics of organic phosphorus was investigated for phosphorus transformation dynamics. • Three-dimensional fluorescence spectroscopy were applied for the structural characteristics and organic molecules. • PCA and RDA analysis were used to discern correlations between phosphorus and physicochemical index. • Wet-dry alternation conditions favor the release of phosphorus from sediment compared to continuous inundation. [ABSTRACT FROM AUTHOR]

In the process of rice cultivation, fertilizer reduction can effectively reduce the concentration of phosphorus (P) in overlying water and leaching water. In this study, the variation characteristics of P in overlying and leaching water under the conditions of fertilizer reduction and straw application and its impact on the environment were studied through a two-season rice field experiment. Four treatments were set, including no fertilizer without straw (CK), conventional fertilization (CF), 20% reduction in nitrogen (N) and P fertilization (RF), and 20% reduction in N and P fertilization with the wheat straw (RFWS). The results showed that RF could effectively reduce the risk of P loss due to its ability to decrease the concentration of P in overlying and leaching water. RFWS increased P concentrations in overlying and leaching water of rice fields. Total dissolved phosphorus (TDP) was the main form of total phosphorus (TP), and soluble reactive phosphorus (SRP) was the main form of TDP. The concentration of TP, TDP, and SRP in the overlying and leaching water peaked on the first day after fertilization, and then gradually decreased. The high-risk period of P loss was 0 to 10 days after fertilization. This study could provide appropriate strategies to reduce the risk of P loss during local rice cultivation and protect local water resources from eutrophication. [ABSTRACT FROM AUTHOR]

Soil phosphorus (P) can be divided into inorganic P (Pi) and organic P (Po). Microorganisms play essential roles in soil P transformation. However, there are many ways to detect P transformation, and the relationship between P forms and microorganisms under long-term fertilization is largely unclear. In this study, soil P forms were analyzed by a chemical sequential fractionation method and solution 31P nuclear magnetic resonance (31P-NMR) technique. Phospholipid fatty acid (PLFA) contents were measured by gas chromatography as the characterization of soil microbial community structures. The objective was to determine the changes of soil P forms and associated microbial community composition in mollisol with long-term fertilization. We sampled soil from a field experiment with 26-year-old continuous maize (Zea mays L.) cropping in Northeastern China. Three fertilization treatments were selected as chemical fertilization (NPK), NPK with crop straw (NPKS), and NPK with manure (NPKM). As shown in 31P-NMR spectra, orthophosphate accounted for 62.8–85.8% of total extract P. Comparison to NPK and NPKS treatments, NPKM application notably increased the concentrations of Po, Olsen-P, orthophosphate, orthophosphate monoester, and total P. Soil P fractions including resin-Pi, NaHCO3-P, NaOH-P, and HCl-P, especially Pi fractions, were enhanced by NPKM. The amounts of total PLFAs and PLFAs in bacteria, Gram-positive (G+) and Gram-negative (G−) bacteria, actinomycetes, and fungi were high in NPKM-treated soil. The percentages of PLFAs in bacteria and fungi in total soil PLFAs were 56.8% and 9.7%, respectively, which did not show any significant difference among the treatments. NPKM increased the proportions (%) of PLFAs in G+ bacteria, and NPKS increased the proportions (%) of G− bacteria in total PLFAs. The composition of soil microbial community was found to be significantly affected by soil total carbon and pH. There was a close relationship between HCl-Pi, NaHCO3-Po, orthophosphate, and pyrophosphate with anaerobe, aerobes, and G+. Manure addition directly increased soil available P concentrations, and indirectly acted through the alterations of anaerobe, aerobes, and G+. It is concluded that long-term NPKM application would lead to the accumulation of labile P and moderately labile P in mollisol through the activity of soil microbes.

Recently, calcium nitrate (CN) has been widely used in contaminated sediments remediation. However, the release of NO3−–N, NO2−–N, and Pb into the overlying water accompanying with the addition of CN may cause a toxic threat to the water ecosystem. Herein, this study investigated the effect of CN addition dosages on the sediment remediation, including oxidation-reduction potential (ORP), acid-volatile sulfide (AVS), phosphorus, nitrogen, and Pb. Results showed that, with the increase of CN addition ratio from 0.5× to 2.0× (from 0.5 to 2.0 times the theoretical CN dosage, based on autotrophic sulfide-driven denitrification), the ORP, AVS, and Fe (II) removal rates had a significant improvement. Moreover, due to the abundant Ca2+ and the oxidization of Fe (II), it would make O–P transformed to Ca–P and Fe/Al–P, which lead to the locking of phosphorus in sediments. However, this study indicated that the more CN added, the more NO3−–N, NO2−–N, and Pb2+ released in the overlying water. In addition, the increase of exchangeable Pb and oxidizable fraction Pb in sediments were characterized, which had a positive correlation with CN dosages (p < 0.01). Thus, secondary pollution needs to be considered for sediment remediation, and adding nitrate directly into sediments may not be suitable for natural water bodies. [ABSTRACT FROM AUTHOR]

Yield increases by use of phosphorus (P) fertiliser has been a defining aspect of last century's agriculture, but in many countries P inputs are now being regulated to avoid ecological damage and improve agricultural sustainability. We tested the hypothesis that P forms and functions in agricultural soils have changed over a period of 50–70 years of agricultural change using topsoils from 35 agricultural sites in North East Scotland compared at 'original' and 'resampled' timepoints. The original dried and archived samples were collected between 1951 and 1981, and resampling took place in the autumn of 2017 with all samples reanalysed at the same time and by same methods. A range of soil extractants, from labile (water soluble) P, carbon (C) and nitrogen (N) forms, to surface exchangeable P (acid ammonium oxalate extraction), to complexed P (NaOH‐EDTA extraction), were compared with agronomic soil test P (modified Morgan; MM‐P), soil pH, and, on a subset of five time pairs (n = 10), specific P compounds using 31P NMR spectroscopy. Whilst MM‐P had declined significantly in time, all soils were originally and remained at high soil P status. In contrast, no change in labile P pools, nor in the more refractory P pools that replenish labile P, were observed. In the subset analysed by NMR, orthophosphate P consistently increased in concentration. This suggests that soil P shows a slow (multidecadal) response to the documented reductions in fertiliser P for the study region. Significantly greater soil pH (by 0.4 units) over time and reduced water‐soluble C and N forms suggests that labile P in contemporary soils exists in a biogeochemical environment of enhanced solubility and in excess to other available macronutrients that control its microbial cycling. This study represents a long and important period of changing drivers acting on soil P change with potential to improve understanding future soil P trajectories. The value of archived historical soils samples is shown, if care in interpretation of storage implications is made. Highlights: Phosphorus fractions in agricultural soil were compared at two timepoints 50–70 years apart.Whilst soil test P declined with time, other labile and refractory P pools did not change.The readjustment of P pools is slow even to substantial change in fertiliser inputs.The investigation of long‐term land use to inform future policy is enabled by soil archives. [ABSTRACT FROM AUTHOR]

Phosphorus is an essential element for life, an innate constituent of soil organic matter, and a major anthropogenic input to terrestrial ecosystems. This paper employed the sequential extraction method for phosphorus fraction to study the distribution of phosphorus in different region in Wuyishan. Hierarchical cluster and correlation were used for investigating the relationship between the phosphorus form and tea quality-related constituents in Zhengyan Rock Tea (ZYRT), Banyan Rock Tea (BYRT) and Zhou Rock Tea (ZRT). The result showed that the concentration of phosphorus in different regions followed this order: ZYRT>BYRT>ZRT. The relative contribution of phosphorus fraction in different regions show the similar trend: Metal Oxide Bound Phosphorus (NaOH-P)>Calcium Bound Phosphorus (HCl-P)> Reduced Phosphorus (BD-P)>Adsorbed Phosphorus (NH4Cl-P). The maximum content of water extract (WE), caffeine (CF), tea polyphenols (TPP) and total amount of amino acids (TAA) in tea leaves is in ZYRT, followed BYRT, and least in the ZRT. The phosphorus forms seem to have no obvious effects on the tea quality in the ZYRT and BYRT area, while TPP and NaOH-P, TPP and HCl-P are significantly positively correlated (r = 0.912, r = 0.956, r = 0.938; p<0.01) in ZRT. [ABSTRACT FROM AUTHOR]

[Display omitted] • Increased the specific surface area of char and facilitate H 2 production. • The non-apatite inorganic phosphorus content in char increased. • Pyrophosphate is generated at the low-temperature reaction stage. • Compositions with alkali metals and phosphorus are stable. • Low-temperature catalytic reaction and high-temperature gasification are noted. This study aims to apply the Absorbing oxygen carriers (AOCs) to induce the migration and transformation of phosphorus compounds during the microwave thermal conversion of sludge so the hard-to-extract organic phosphorus (OP) can be converted to easy-to-extract inorganic phosphorus (IP) and be enriched onto the sludge char. The AOCs were recycled by screen separation from the IP-rich sludge char, with the latter being a renewable phosphorus source from sludge. The AOCs in this novel process enhanced the conversion efficiency of OP into non-apatite inorganic phosphorus (NAlP), which was further converted to apatite inorganic phosphorus (AP). Most phosphorus in the sludge char is presented in the form of orthophosphate. [ABSTRACT FROM AUTHOR]

[Display omitted] • PSB significantly improved algal growth in both OP and IIP by dissolving P. • Organic or even mixture P was more favorable for the algal growth. • Maximum algal lipid productivity increase of 2.77 and 4.39-fold by OP and PSB. • OP and PSB improved algal lipid quality by adjusting the proportion of SFA. • PSB upregulated algal genes relating to the growth and lipid synthesis. Effects of a phosphorus-solubilizing bacteria (PSB) Bacillus megatherium on growth and lipid production of Chlorella sorokiniana were investigated in synthesized swine wastewater with dissolved inorganic phosphorus (DIP), insoluble inorganic phosphorus (IIP), and organic phosphorus (OP). The results showed that the PSB significantly promoted the algal growth in OP and IIP, by 1.10 and 1.78-fold, respectively. The algal lipid accumulation was also greatly triggered, respectively by 4.39, 1.68, and 1.38-fold in DIP, IIP, and OP. Moreover, compared with DIP, OP improved the oxidation stability of algal lipid by increasing the proportion of saturated fatty acids (43.8 % vs 27.9 %), while the PSB tended to adjust it to moderate ranges (30.2–41.6 %). Further, the transcriptome analysis verified the OP and/or PSB-induced up-regulated genes involving photosynthesis, lipid metabolism, signal transduction, etc. This study provided novel insights to enhance microalgae-based nutrient removal combined with biofuel production in practical wastewater, especially with complex forms of phosphorus. [ABSTRACT FROM AUTHOR]

The phosphorus (P) leaching from continuous fertilization is generally neglected in mollisol. The in situ leaching loss of phosphorus (P), especially dissolved organic P, is poorly quantified under organic amendments given its potential environmental risks. In this study, we conducted an in situ soil column experiment, instead of the traditional measuring of the soil layer, in the mollisol area of northeast China to investigate the seasonal variations in different P forms under three typical fertilization practices, including chemical fertilizer (CF), CF supplemented with straw (CFS), and CF co-applied with straw and manure (CFSM). Compared with the CF treatment, CFS treatment generally reduced the leaching loss of dissolved organic P by 57.3% to reduce the total P loss, while the CFSM treatment increased the leaching loss of dissolved inorganic P by 20.9% to increase the total P loss. Other than the effects of management practices, precipitation and temperature-oriented environmental factors significantly affected the seasonal variation in leaching loss of both the dissolved and particulate P forms. We conclude that straw incorporation into the mollisol of northeast China is recommended, considering its low leaching risk of P, while a co-amendment of straw and manure resulted in the opposite. Despite the slight environmental risk of P leaching loss (0.75–1.95% of external P input per year) practically quantified by in situ experiments, a proper reduction in chemical P input with organic amendments may be an effective P fertilizer management strategy in mollisol areas.

Lanthanum-modified bentonite (LMB) is widely used for eutrophication control and has demonstrated good efficiency in some eutrophic lakes. However, the efficiency of LMB on eutrophication control in some eutrophic lakes, where the structure of food webs is mainly dominated by omni-benthivorous fish, remains ambiguous. Omni-benthivorous fish usually disturbs sediment and promotes the release of internal nutrients, the effect of which on the efficacy of LMB remains to be studied. Thus, a 30-day mesocosm experiment was conducted to determine whether omni-benthivorous fish disturbance and LMB would cause antagonistic responses. LMB significantly reduced dissolved P concentration in overlying water, converting mobile P to bound P in the surface layer of sediment in the absence of crucian carp (Carassius carassius). However, there were significantly negative interaction effects between LMB and crucian carp. Although LMB still effectively reduced the total dissolved phosphorus (TDP) and soluble reactive phosphorus (SRP) concentrations of overlying water in the presence of crucian carp, it had limited efficacy on inhibiting the increased concentrations of suspended solids, particulate nutrients, and chlorophyll a (Chl a) due to crucian carp disturbance. Furthermore, the crucian carp disturbance also increased the risk of mobile P releasing from surface sediment, whether with or without LMB application. The results indicated that the efficacy of LMB was insufficient to offset the negative effect of omni-benthivorous fish disturbance on eutrophication control. Hence, the omni-benthivorous fish also need to be considered for eutrophication control in shallow eutrophic lakes. Some measures need to be taken to control the biomass of omni-benthivorous fish. [ABSTRACT FROM AUTHOR]

Microbes associated with phosphorus (P) cycling are intrinsic to soil P transformation and availability for plant use but are also influenced by the application of P fertilizer. Nevertheless, the variability in soil P in the field means that integrative analyses of soil P cycling, microbial composition, and microbial functional genes related to P cycling remain very challenging. In the present study in the North China Plain, we subjected the bacterial and fungal communities to amplicon sequencing analysis and characterized the alkaline phosphatase gene (phoD) encoding bacterial alkaline phosphatase in a long-term field experiment (10 years) with six mineral P fertilization rates up to 200 kg P ha–1. Long-term P fertilization increased soil available P, inorganic P, and total P, while soil organic P increased until the applied P rate reached 25 kg ha–1 and then decreased. The fungal alpha-diversity decreased as P rate increased, while there were no significant effects on bacterial alpha-diversity. Community compositions of bacteria and fungi were significantly affected by P rates at order and family levels. The number of keystone taxa decreased from 10 to 3 OTUs under increasing P rates from 0 to 200 kg ha–1. The gene copy numbers of the biomarker of the alkaline phosphatase phoD was higher at moderate P rates (25 and 50 kg ha–1) than at low (0 and 12.5 kg ha–1) and high (100 and 200 kg ha–1) rates of P fertilization, and was positively correlated with soil organic P concentration. One of the keystone taxa named BacOTU3771 belonging to Xanthomonadales was positively correlated with potential functional genes encoding enzymes such as glycerophosphoryl diester phosphodiesterase, acid phosphatase and negatively correlated with guinoprotein glucose dehydrogenase. Altogether, the results show the systematic effect of P gradient fertilization on P forms, the microbial community structure, keystone taxa, and functional genes associated with P cycling and highlight the potential of moderate rates of P fertilization to maintain microbial community composition, specific taxa, and levels of functional genes to achieve and sustain soil health.

A laboratory experiment was conducted to determine the extent and the importance of phosphorus (P) fractions of some agriculturally important Sudanese soils on P availability. The soils were gathered from different locations in Sudan, to represent three different orders: Aridisols (Um Dum soil, North Kordofan state), Alfisols (Hagu soil, Senar state), and Vertisols (Hosh soil, Gezira state). The soil P was fractionated using an authenticated procedure. The results showed that the soils had low total, organic and available P contents. Most of the inorganic soil P was present in the Fe-Al fraction in Um Dum soil (> 50%), and about 40% of this fraction in Hagu soil, but, only 20% in alkaline Hosh soil. The Ca-P fraction constituted > 60% in Hosh soil, about 40% in Hagu soil and 20 % in Um Dum soil. The available P in the top soils studied was positively related to the percent sum of Al+Fe -P of the total P, and was negatively related to the percent Ca-P fraction content of the total P. It has been proposed that the P sorption starts by exchange with singly coordinate Fe or Al- OH clay (OH− edge group) and quickly reorganizes into more stable and less soluble ring forms especially at pH more than 7.0, Alkaline pH more than 8.0 in soil like Hosh, will in presence of Ca, favour with time, the formation of inactive less soluble form like octacalcium phosphates and apatites at expense of the initial Al and Fe-P forms which are less stable at alkaline pH.

Microbes associated with phosphorus (P) cycling are intrinsic to soil P transformation and availability for plant use but are also influenced by the application of P fertilizer. Nevertheless, the variability in soil P in the field means that integrative analyses of soil P cycling, microbial composition, and microbial functional genes related to P cycling remain very challenging. In the present study in the North China Plain, we subjected the bacterial and fungal communities to amplicon sequencing analysis and characterized the alkaline phosphatase gene (phoD) encoding bacterial alkaline phosphatase in a long-term field experiment (10 years) with six mineral P fertilization rates up to 200 kg P ha–1. Long-term P fertilization increased soil available P, inorganic P, and total P, while soil organic P increased until the applied P rate reached 25 kg ha–1 and then decreased. The fungal alpha-diversity decreased as P rate increased, while there were no significant effects on bacterial alpha-diversity. Community compositions of bacteria and fungi were significantly affected by P rates at order and family levels. The number of keystone taxa decreased from 10 to 3 OTUs under increasing P rates from 0 to 200 kg ha–1. The gene copy numbers of the biomarker of the alkaline phosphatase phoD was higher at moderate P rates (25 and 50 kg ha–1) than at low (0 and 12.5 kg ha–1) and high (100 and 200 kg ha–1) rates of P fertilization, and was positively correlated with soil organic P concentration. One of the keystone taxa named BacOTU3771 belonging to Xanthomonadales was positively correlated with potential functional genes encoding enzymes such as glycerophosphoryl diester phosphodiesterase, acid phosphatase and negatively correlated with guinoprotein glucose dehydrogenase. Altogether, the results show the systematic effect of P gradient fertilization on P forms, the microbial community structure, keystone taxa, and functional genes associated with P cycling and highlight the potential of moderate rates of P fertilization to maintain microbial community composition, specific taxa, and levels of functional genes to achieve and sustain soil health. [ABSTRACT FROM AUTHOR]

Sediment samples and concentrated green algae from Taihu Lake were used as experimental materials for indoor column culture. Under the influence of algae decomposition, the dynamic variations of pH, dissolved oxygen ( DO), total phosphorus ( TP), total dissolved phosphorus (TDP) and active phosphate (PO3-4) in overlying water were studied. The results showed that the death rate of green algae in anaerobic culture was faster than that in aerobic culture. The process of algal death gradually consumed oxygen, produced carbon dioxide and even released small molecular organic acids, which made the DO and pH in overlying water of "algal anaerobic" group decrease obviously. During the column culture period ( 1 - 20 d), the concentrations of PO!- and TDP in overlying water of "blank aerobic" group increased significantly, indicating that parts of sediment phosphorus were released into the overlying water under aerobic culture environment. Whereas PO3-4- concentrations in overlying water of "algae aerobic" group only increased within 10 - 20 d, which was mainly caused by phosphorus release from algae decomposition in the later stage of column culture. Relatively, PO3-4- and TDP concentrations in overlying water of "algal anaerobic" group in the 10 - 20 d changed little. These may be related to the adsmption of PO3-4- by algae residue and suspended matter in overlying water during the later stage of column culture, which needed further study. The study indicated that green decomposition could obviously reduce DO, pH in water and release phosphorus into water, but there were some differences in the period of phosphorus release under different culture conditions. [ABSTRACT FROM AUTHOR]

Microorganisms play an important role in the circulation of phosphorus (P) in the sediment of coastal wetland ecosystems. In this study, solution 31P nuclear magnetic resonance (NMR) was used to determine different forms of P in the sediments of four different seagrass meadows and a bare tidal flat, while high-throughput 16S and ITS rRNA gene sequencing was used to determine the microbial community composition. The solution 31P-NMR spectra revealed six forms of the P compounds detected by the NaOH-EDTA extraction of sediments, where Ortho-P was the most dominant P compound, followed by Mono-P. The Po compounds were more varied in the seagrass meadow sediments and more abundant compared to the bare tidal flat. Bacterial communities in the sediments collected from E. acoroides and fungal communities in the bare tidal flat were relatively different from those at the other sites. The relative abundance of P-cycling-related fungi belonging to the phylum Ascomycota was 26.20% and was much higher than that of bacteria (only 0.29%) belonging to the class Bacilli. Mono-P was the major factor determining the distribution of P-cycling-related fungi and negatively correlated with the relative abundance of Aspergillus and Trichoderma. We believe that fungi can affect P forms in the sediment of seagrass meadows more than bacteria. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the connection of phosphorus (P) forms with peatland succession and history of fire in Tuqiang peatland, a 57 cm peat core was sampled with high-resolution (1-cm intervals) in the north of the Great Khingan mountain (Northeast China). AMS 14C dating techniques combined with sequential chemical extraction was used to determine and calculate the accumulation rates of phosphorus fractions. Phosphorus forms were mainly composed with NaOH-P o , hot concentrated HCl–P (conc. HCl–P) and residual-P. Active phosphorus pools were enriched in the top 8–10 cm of the peat surface. The concentrations of organic phosphorus forms and residual-P were generally high during 1200 to 500 cal yr BP, and the accumulation rate of that gradually decreased since 1600 cal yr BP. Both of concentration and accumulation of organic phosphorus decreased after 600 cal yr BP. The accumulation rate of organic phosphorus forms significantly corresponded with peat development frequency, pollen records and other paleo evidence. The concentration and accumulation of organic phosphorus, especially NaOH-P o, was positively connected with concentration of pollen and Cyperaceae , and decreased when relative abundance of moss or shrubs occurred. Fire changed the vegetation community, decreased the concentration and accumulation of P o , and reduced inactive P o /P i at the same time. Fire events could also leave geochemical evidence on peat. It is necessary to consider the both changes of inactive P o /P i and organic phosphorus accumulation rate when reflected the fire history by phosphorus in core. [ABSTRACT FROM AUTHOR]

Understanding the spatial characteristics of soil properties would be helpful in recognizing their relationship and the development of site-specific management techniques. The paper aims to identify any spatial heterogeneity of the P-related properties in a plot scale and to explain the main mechanisms influencing this variability in the upper layer of arable Luvisols. Samples were collected from the upper soil horizon in April and August 2008. The content of the total (PTOT), available (PAVAIL), inorganic (PINORG) and organic (PORG) form of P and the acid (ACP) and alkaline (ALP) phosphatase activity were assessed. The ALP was significantly higher in April than in August, while the ACP did not differ between the sampling dates. The PINORG was significantly higher in August than in April, while the other P forms did not differ seasonally. The PORG content, PAVAIL concentration and ALP activity in April revealed a moderate spatial variability, while the PAVAIL content and ACP in August showed a strong variability. No significant relationship was found between any P form and the phosphatase activity. The results are essential to predict the contribution of internal factors in the total variability of soil properties that can interfere with the influence of soil management practices. [ABSTRACT FROM AUTHOR]

Humin plays a key role in various environmental processes like nutrient retention, carbon sequestration together with contaminant migration. Due to the resistance of humin to microbial degradation, exploring the mineralization process of phosphorus associated with humin is relevant to evaluate the lability of organic phosphorus and to develop a sustainable nutrient management strategy in ecosystems. Herein, humin was obtained from three climatically contrasting forest soils, including brown coniferous forest soil (Humic Cambisol), dark brown soil (Haplic Luvisol), as well as yellow brown soil (Haplic Luvisol), by treatment via a mixture of HF-HCl after soluble humic components were removed. The lability of phosphorus bound to humin and humic acid was examined by hydrolysis reaction with phytase from wheat, acid phosphatase from potato, and nuclease P1 from Penicilliumcitrinum alone or in combination. The results demonstrated that humin contained labile inorganic phosphorus as well as organic phosphorus. In the labile organic phosphorus, phytate-like phosphorus displayed the greatest proportion followed by simple monoester phosphorus and polynucleotide-like phosphorus. The labile total phosphorus was lower in humin than in humic acid. Among the three soils, labile total phosphorus was greater in brown coniferous forest soil than in yellow brown soil for humin and in dark brown soil than in yellow brown soil for humic acid. The labile total phosphorus was positively correlated well with Mn and Zn contents in humin and humic acid. Moreover, the lower proportion of labile total phosphorus in yellow brown soil could also be attributed to its higher pH value and silt and clay-size fractions compared to brown coniferous forest soil and dark brown soil. Our results can provide new information on the potential role of humin in P cycling and nutrition and are of significance for sustainable nutrient management in ecosystems. [ABSTRACT FROM AUTHOR]

The aim of the research was to complement the knowledge on profile distribution and accumulation of phosphorus forms in the soils changed under the influence of secondary organic matter transformation process in dehydrated peatlands. The soil research was carried out in the upper Liwiec river valley in the middle-east of Poland. In the soil material taken from the moorsh (M1, M2, M3) and peat (O) horizons of the Murshic Histosols, the physical and chemical properties were determined and the soil phosphorus fractions with different activity in the environment by sequential extraction method were separated. The profile distribution of the total phosphorus content (TP) and values of carbon/phosphorus (TC/TP) ratio were characteristic for dehydrated peat soils included in the secondary transformation process (M1>M2>M3>O). This process also increased the contribution of the available phosphorus forms (NH4Cl-P), forms bound on the surface of iron (III) and manganese (IV) oxides and hydroxides (redox-P), as well as mineral (mHCl-P) and organic (oHCl-P) forms separated by 0.5 M HCl. Significant accumulation of the phosphorus compounds in the moorsh horizons of the investigated soils can be considered as a potential threat to the natural environment of the studied area due to the risk of decomposition of the phosphorus compounds when the area will be rehydrated. [ABSTRACT FROM AUTHOR]

Phosphorus deficiency is one of the soil factors affecting crop production in Southern part of Nigeria and understanding its distributions in rhizosphere soils will help in its management. This investigation examined some variations in soil properties and inorganic phosphorus forms within the rhizosphere of three annual crops, viz groundnut (Arachis hypogea), bean (Phaseolus vulgaris) and okra (Abelmoschus esculentus) on a loamy sand, typic haplustult soil. The work was sited at the research farm of the University during 2016 planting season and the region lies within the latitude of 5° 38¹N and longitude 6° 97¹ E. At 10 weeks after planting, both the rhizosphere soil (soils within 2 mm region of the test crops) and bulk soil or control (soils away from the root zone) from the experimental plots that were planted with bean, groundnut and okra were sampled, air dried and analyzed in the laboratory. Results showed significant effect (p = 5%) on soil moisture content, soil pH, organic carbon and exchangeable bases between the bulk soil and the rhizosphere. The highest value of saloid bound P (7.77 mg/kg) was found within the bean root zone while the highest value of phosphorus bound to Al (Al - P) (13.27 mg/kg) was found in okra root zone. Highest value of occluded -- phosphorus (46.07 mg/kg), Fe -Al--P (40.62 mg/kg) and Ca-P (6.77 mg/kg) were recorded in groundnut root zones. Significant relation occurred between occluded--P with bulk density, exchangeable Ca and ECEC (effective cation exchange capacity), saloid bound P with BS (base saturation), moisture content as well as organic carbon, Al--P with available phosphorus and moisture content while Ca--P and Fe-Al--P had significant relation with available phosphorus and effective cation exchange capacity. As a result of different concentrations of inorganic phosphorus forms within these roots zones, appropriate agronomic management practices such as crop rotation, mixed cropping and shifting cultivation is recommended for sustainable phosphorus management in the studied soil. [ABSTRACT FROM AUTHOR]