Organic Forms Of Phosphorus Research Articles

Organic Phosphorus Fractions in Relation to Soil Aggregate Fractions of Black Soil

Knowledge of long-term phosphorus behavior is essential to improve soil structure, nutrient supply potential, and the sustainability of cropping systems. A 45-year long-term experimental trial was used to observe organic phosphorus fractionation and its effects on soil aggregation and nutrient distribution at three depths (0–20, 20–40, and 40–60 cm) in Vojvodina Province, Serbia, under maize monoculture and maize/barley rotation. Five fertilizing systems were studied, including Control, NPK, NPK + maize remains, NPK + manure, and NPK + manure in rotation. Soil aggregates were fractionated into four size categories (>2000, 2000–250, 250–53, and <53 μm) using a wet sieving method. The samples were analyzed for main indicators, including different forms of phosphorus, total and available (PT and PA), as well as its organic forms (Labile Po, Biomass Po, Mod. Labile Po, Fulvic acid Po, Humic acid Po, and Resistant Po), and other fertility parameters. Significant differences in total and available phosphorus as well as all observed organic phosphorus fractions were evident between treatments with and without organic amendments, particularly in the 0–20 and 20–40 cm soil layers. Moderately labile P forms were dominant across all treatments, while labile forms constituted a smaller proportion. The most notable differences between treatments were observed in the labile and moderately labile forms, as well as in the resistant form of organic phosphorus. Manure application led to increased nutrient content in macroaggregates (>250 μm) compared to microaggregates. Microaggregates (<250 μm) were predominant across all depths, while stable structural aggregates did not show a significant increase after manure application. PCA highlighted significant correlations between soil characteristics, including total and available P, total organic carbon, clay content, and enzyme activity, across different aggregate sizes and organic P fractions. Overall, long-term mineral fertilization combined with organic amendment application induced variations in phosphorus fractions and the content of carbon, nitrogen, and phosphorus associated with aggregates in the first two soil layers, except for aggregate size classes.

Production of fungal phytases in solid state fermentation and potential biotechnological applications.

Phytases are important enzymes used for eliminating the anti-nutritional properties of phytic acid in food and feed ingredients. Phytic acid is major form of organic phosphorus stored during seed setting. Monogastric animals cannot utilize this phytate-phosphorus due to lack of necessary enzymes. Therefore, phytic acid excretion is responsible for mineral deficiency and phosphorus pollution. Phytases have been reported from diverse microorganisms, however, fungal phytases are preferred due to their unique properties. Aspergillus species are the predominant producers of phytases and have been explored widely as compared to other fungi. Solid-state fermentation has been studied as an economical process for the production of phytases to utilize various agro-industrial residues. Mixed substrate fermentation has also been reported for the production of phytases. Physical and chemical parameters including pH, temperature, and concentrations of media components have significantly affected the production of phytases in solid state fermentation. Fungi produced high levels of phytases in solid state fermentation utilizing economical substrates. Optimization of culture conditions using different approaches has significantly improved the production of phytases. Fungal phytases are histidine acid phosphatases exhibiting broad substrate specificity, are relatively thermostable and protease-resistant. These phytases have been found effective in dephytinization of food and feed samples with concomitant liberation of minerals, sugars and soluble proteins. Additionally, they have improved the growth of plants by increasing the availability of phosphorus and other minerals. Furthermore, phytases from fungi have played an important roles in bread making, semi-synthesis of peroxidase, biofuel production, production ofmyo-inositol phosphates and management of environmental pollution. This review article describes the production of fungal phytases in solid state fermentation and their biotechnological applications.

The effect of natural organic matter (NOM) on the distribution and resources of mobile phosphorus in the bottom sediments of small retention reservoirs

The purpose of the work detailed here was to determine the impact of the distribution of natural organic matter and grain size on the resources and distribution of mobile phosphorus in the bottom sediments of small reservoirs located in catchments subject to different levels of anthropopressure. The research objects were five small reservoirs located in southeast Poland. In small retention reservoirs, it is the anthropogenic impact of the catchment and its geological structure, and to a lesser extent sediment granulation, that determine the distribution of phosphorus fractions (especially in inorganic compounds) and the share of total P they account for. In general, a higher level of contamination of sediments with organic matter (OSION increase) is shown to be associated with a higher content of the organic fraction of phosphorus and easily decomposable organic matter. Within small retention reservoirs under significant anthropogenic influence from the catchment, sandy sediments compared with silty sediments were significantly less loaded with potentially mobile phosphorus as well as with organic forms of phosphorus and (sometimes) nitrogen. The occurrence of humic-metal-phosphate complexes is determined by there being sufficient organic matter, especially humic fractions. Fractions of inorganic phosphorus compounds and organic matter have the terrigenous source of these pollutants in common. The organic sediment index can serve as an adjunctive indicator with which to assess the potential ability of the sediments in small retention reservoirs to internal supply of the water column in nutrients.

Effect of tree species and substrate properties on organic phosphorus forms in afforested Technosols

AbstractPlanted vegetation is considered one of the most important soil‐forming factors in the reclamation of degraded post‐mining lands for forestry. The objective of this study was to compare the effect of N‐fixing tree species and non‐N‐fixing tree species on the organic phosphorus (Porg) forms in technosols developing from various substrates. Samples were taken from the uppermost layer (depth 0–5 cm) of technosols afforested with black locust (Robinia pseudoacacia), black alder (Alnus glutinosa), silver birch (Betula pendula), and scots pine (Pinus sylvestris). Samples of the tree foliage and the O‐horizons were taken as well. The studied technosols developed from Quaternary sands (sands), fly ashes after lignite combustion (ashes), and Miocene clays (clays). The soil samples were measured for the contents of labile (POlab) and moderately labile organic phosphorus (POmod), phosphorus contained in fulvic and humic acids (Pfulv and Phum, respectively), and residual organic phosphorus (POres). The foliage and O‐horizon samples were measured for the concentrations of C, N, and P. The N‐fixing tree species had higher P concentration in their foliage than non‐N‐fixing tree species. However, in the O‐horizon, the highest P concentration was determined under birch and not under N‐fixers. The effect of tree species on the organic P (Porg) concentrations in the mineral soil was limited with significantly lower Porg concentrations under pine. The soil under this species contained less Pfulv, Phum, and POres. However, the percentages of POlab, POmod, Pfulv, Phum, and POres in soil Porg were nearly the same under all tree species. The largest effect on the Porg concentration and the contents of particular Porg fractions was from the substrate type. Sands contained much less Porg than the clays and ashes, but their percentage of POlab in Porg was much higher than in the two other substrates. We conclude that N‐fixing trees do not affect the concentration of labile organic P, and the major factor controlling this Porg fraction is the soil substrate quality.

Phosphorus Species, Influencing and Release Risks Assessment in Mangrove Wetland Sediments of Dongzhai Harbor on Hainan Island, China

Mangrove wetlands are superior sites for the deposition of various pollutants, but they are also more susceptible to environmental contamination. To investigate the health threats of phosphorus to mangrove ecosystems, this study presents the distribution, chemical speciation and factors influencing phosphorus (P) forms in 38 surface sediments from the mangrove wetlands of Dongzhai Harbor on Hainan Island, China. P forms were measured using the sequential extraction (SEDEX) procedures. The results showed that the total phosphorus content in the sediment was at a high level, and there was a significant spatial variability of phosphorus in each form. Among them, inorganic phosphorus accounted for 74.64% of the total phosphorus, and organic phosphorus accounted for 25.35% of the total phosphorus. Among the inorganic phosphorus, detrital limestone phosphorus and Ca-bound phosphorus were dominant, while the content of exchangeable phosphorus and Fe-bound phosphorus had a smaller percentage. The concentration of biologically available phosphorus, ranged from 1.76 umol/g to 18.57 umol/g, and the Fe-bound and organic forms of phosphorus had a controlling effect on it. Based on Corg/OP, N/P and land use surveys, it was concluded that phosphorus was mainly an exogenous input. The correlation analysis concluded that the main sources of phosphorus in the study area are agriculture and aquaculture. The development of agriculture and aquaculture led to moderate levels of phosphorus pollution in the study area as a whole, with more serious a phosphorus pollution at the wetland park in the southeast corner of Dongzhai Harbor and in the western areas, with lush vegetation and developed river systems, mainly influenced by human activities, topography, vegetation and water system conditions.

Distribution Characteristics of Soil Phosphorus Forms and Phosphatase Activity at Different Altitudes in the Soil of Water-Level-Fluctuation Zone in Pengxi River, Three Gorges Reservoir

Phosphatases play important roles in converting organic phosphorus into inorganic phosphorus in soil. However, studies from this perspective on the water-level-fluctuation zone (WLFZ) of the Three Gorges Reservoir are limited. In this study, phosphatase activity and the forms of phosphorus were analyzed. Soil samples were collected in the river basin of the Penxi River in the WLFZ during a drying period. The correlation between phosphatase activity and phosphorus forms and the impacts of phosphatase activity on the phosphorus forms were analyzed. The results showed that the contents of H2O-Pi, NaHCO3-Pi, and NaOH-Pi in the soils of the WLFZ were higher than those in the soils by the river. In addition, a higher altitude resulted in higher contents of bio-enzymatically hydrolysable phosphorus and NaOH-Po. Furthermore, redundancy analysis (RDA) showed that the contents of organic matter and amorphous Fe and Mn were the main factors affecting soil organic phosphorus forms. The average activities of acid phosphomonoesterase (ACP), alkaline phosphomonoesterase (ALP), phosphodiesterase (PDE) (all in p-NP), and phytase (PAE) (in P) in the soils of the WLFZ were 1.40, 2.60, 0.44, and 11.43 μmol·(g·h)-1, respectively. Moreover, the activities of different phosphatases increased with altitude. Soil plant biomass and microbial biomass were important reasons for the difference in spatial distribution of phosphatase activity in the soil of the WLFZ. Phosphatase activities were significantly positively correlated with the contents of organic phosphorus forms but negatively correlated with the content of bioavailable phosphorus. A higher soil phosphatase activity and a lower content of bioavailable phosphorus were usually detected in soil samples taken at a higher altitude. In the early stage of flooding, phosphatase converted organic phosphorus into inorganic phosphorus at a relatively high rate, and the risk of phosphorus release to the overlying water body was also high. This study contributed to a comprehensive understanding of the geochemical cycle of soil phosphorus in the soil of the WLFZ.

Utilization of phosphonic acid compounds by marine bacteria of the genera Phaeobacter, Ruegeria, and Thalassospira (α-Proteobacteria).

Phosphonic acid (phosphonate) that possesses a carbon-phosphours bond is a chemically stable form of organic phosphorus. Various phosphonic acids are widely distributed in oceanic waters; in particular, methylphosphonic acid (namely methylphosphonate) is believed to be responsible for global methane production. To discuss the microbial degradation of phosphonic acids, we investigated the utilization of phosphonic acid compounds by cultures of marine bacteria, Phaeobacter sp., Ruegeria sp. (Rhodobacterales), and Thalassospira sp. (Rhodospirillales). These bacterial cultures were able to grow on methylphosphonic acid as well as on the tested alkyl-, carboxy-, aminoalkyl-, and hydroxyalkyl-phosphonic acid compounds. Cell yields and growth rates of Ruegeria and Thalassospira cultures grown on methyl-, ethyl-, propyl-, and butyl-phosphonic acid compounds tended to decrease with increasing alkyl chain length. In contrast, Phaeobacter sp. grew well on such alkyl-phosphonic acids. Our results suggest that these marine bacteria, which exhibit varied utilization, are involved in microbial degradation of various phosphonic acid compounds.

Selective utilization of phosphorus compounds by Chaetoceros tenuissimus (Bacillariophyceae): Approach using 31P nuclear magnetic resonance analysis

SUMMARYSeveral diatom species can utilize various forms of organic phosphorus via enzymatic hydrolysis. The present study identified which phosphorus compounds are preferentially utilized by planktonic diatom Chaetoceros tenuissimus cultures using a 31P nuclear magnetic resonance (NMR)‐based method. Our 31P NMR analysis, which involves a sample extraction procedure using DIAION™ CR11, detected and quantified phosphorus compounds present at concentrations of at least 7.5 μM in the seawater‐based media, including orthophosphate, phosphate monoester, phosphate diester, phosphonate, and other compounds. Based on this analysis, we examined the temporal variations of phosphorus compounds in C. tenuissimus cultures in which orthophosphate, phosphate monoester, phosphate diester, and phosphonate compounds were present simultaneously. Cells pre‐grown under phosphorus‐replete conditions utilized orthophosphate as the preferential phosphorus source and switched to phosphate monoester after exhausting orthophosphate. Enzymatic activity for phosphate monoester hydrolysis, namely phosphomonoesterase (synonym to alkaline phosphatase) activity, appeared when C. tenuissimus began to utilize phosphate monoester. In contrast, C. tenuissimus pre‐grown on phosphorus‐depleted media simultaneously hydrolyzed phosphate monoester and phosphate diester compounds, released orthophosphate from these compounds, and utilized the released orthophosphate and original orthophosphate without discrimination. Overall, we demonstrated that 31P NMR‐based method can comprehensively analyze the variations of dissolved phosphorus compounds in diatom cultures. Our results showed selective utilization of phosphorus compounds by C. tenuissimus and suggested that phosphate monoester and phosphate diester compounds were important phosphorus sources for this diatom in orthophosphate‐depleted coastal waters.

Tomato plant responses induced by sparingly available inorganic and organic phosphorus forms are modulated by strigolactones

Background and aimsPhosphorus (P) is an essential nutrient for plant growth, but is also one of the least accessible in soil. Plants have evolved several strategies to cope with P deficiency and recently the role of the phytohormones strigolactones (SLs) in modulating tomato plants acclimation to P shortage has been described. How SLs regulate the use of P from sparingly accessible P sources, such as organic P or precipitated metal-P systems, is however still unknown in tomato.MethodsIn this study, we compared P acquisition strategies of wild-type (WT) and SL-depleted tomato plants grown hydroponically in the presence of dissolved inorganic phosphate (Pi), dissolved myo-inositol hexaphosphate (myoInsP6), or their coprecipitated form following Fe(II) oxidative precipitation.ResultsIrrespective of the P treatment, SL-depleted plants accumulated more P in their tissues than the WT, possibly due to the constitutively higher expression of high-affinity P transporters and activity of P-hydrolyzing enzymes. Wild-type plants were conversely more effective at acidifying their growth medium and exuding more organic compounds in the presence of dissolved myoInsP6 or coprecipitated forms of P, but this behaviour did not translate into a higher P acquisition.ConclusionsThe two genotypes activated different subsets of responses to bypass low P bioavailability, although the P acquisition efficiency (PAE) was not effectively increased. Strigolactone-depleted plants achieved higher PAE values than WT plants regardless of the applied P form, highlighting a central role of SLs in controlling P uptake and optimizing the cost/benefit ratio of P acquisition.

Soluble organic nutrients induce ClaPhys expression to enhance phytase activity of watermelon roots

AbstractApplication of organic fertilisers is beneficial to the quality and yield of crops. Myo‐inositol phosphate is an abundant form of organic phosphorus (Po) in organic manure and soil, which could release phosphate (Pi) and likely be absorbed by plant after it was hydrolysed by phytase. However, whether plant roots respond to organic fertiliser to adapt myo‐inositol phosphates utilisation is not clear. Experiments were carried out to investigate the responses of phytase gene expression and enzyme activity, as well as root architecture to organic fertiliser application. The results showed that Cow‐dung‐based organic fertiliser contains 2.30 g/kg soluble P, including 0.08 g/kg myo‐inositol phosphates P. Organic acid addition promotes myo‐inositol phosphates solubility in organic fertiliser. Partial substitution of Pi with P from organic fertiliser upregulated the expression of ClaPhy1, ClaPhy2 and ClaPhy3 in roots, while it did not change ClaPHT1 family expression. Root phytase activity increased markedly at 25–30% organic fertiliser substitution rates. P concentration in watermelon leaves increased when 25% Pi was substituted with P from organic fertiliser. Organic fertiliser supply also promoted lateral root density and root hair length. In conclusion, organic fertiliser contains soluble myo‐inositol phosphates, more of which was dissolved by organic acids secreted from plant roots. Substitution of Pi with P from organic fertiliser upregulated ClaPhy genes expression and enhanced root phytase activity, as well as increased lateral root number and root hair density. Myo‐inositol phosphates hydrolysis and root morphology adaptation facilitate watermelon utilisation of myo‐inositol phosphates P in organic fertiliser. This study provides evidence to advance utilisation of myo‐inositol phosphates P from organic fertiliser by plant roots via up‐regulation of ClaPhy expression which increased phytase secretion, and optimised root morphology.

Phosphonates as Unique Components of Plant Seeds-A Promising Approach to Use Phosphorus Profiles in Plant Chemotaxonomy.

Phosphorus is one of the most important elements essential for all living beings. Plants accumulate and store phosphorous in various forms that have diverse physiological and biochemical functions. In this study, we determine and then examine the phosphorus profiles of seeds of plants belonging to different taxa based on extractable inorganic phosphates and organic forms of phosphorus. We paid particular attention to the presence of natural phosphonates in the tested materials. The inorganic phosphates were determined colorimetrically, whereas phosphorus profiles were created by using 31P NMR spectroscopy. Our study on phosphorus profiles revealed that the obtainedsets of data vary significantly among the representatives of different taxa and were somehow specific for families of plants. It should be emphasised that the measurements obtained using 31P NMR spectroscopy undoubtedly confirmed—for the first time—the presence of phosphonates among the natural components of plant seeds. Hence, the classification of plants considering the phosphorus profiles, including the presence of phosphonates, may be a new additional chemotaxonomic feature.

Role of metal complexation on the solubility and enzymatic hydrolysis of phytate.

Phytate is a dominant form of organic phosphorus (P) in the environment. Complexation and precipitation with polyvalent metal ions can stabilize phytate, thereby significantly hinder the hydrolysis by enzymes. Here, we studied the stability and hydrolyzability of environmentally relevant metal phytate complexes (Na, Ca, Mg, Cu, Zn, Al, Fe, Al/Fe, Mn, and Cd) under different pHs, presence of metal chelators, and thermal conditions. Our results show that the order of solubility of metal phytate complexes is as follows: i) for metal species: Na, Ca, Mg > Cu, Zn, Mn, Cd > Al, Fe, ii) under different pHs: pH 5.0 > pH 7.5), and iii) in the presence of chelators: EDTA> citric acid. Phytate-metal complexes are mostly resistant towards acid hydrolysis (except Al-phytate), and dry complexes are generally stable at high pressure and temperature under autoclave conditions (except Ca phytate). Inhibition of metal complex towards enzymatic hydrolysis by Aspergillus niger phytase was variable but found to be highest in Fe phytate complex. Strong chelating agents such as EDTA are insufficient for releasing metals from the complexes unless the reduction of metals (such as Fe) occurs first. The insights gained from this research are expected to contribute to the current understanding of the fate of phytate in the presence of various metals that are commonly present in agricultural soils.

The oxidative immobilization of phosphonate by simulated solar light mediated peroxi-coagulation process sustained by the iron-air fuel cell

Phosphonates are an important type of phosphorus-containing compounds and is of primary concern due to its eutrophication potential. Herein, we achieved simultaneously oxidative immobilization of phosphorus from ethylene diamine tetra (methylene phosphonic acid) (EDTMP) in the simulated solar light mediated peroxi-coagulation process sustained by the iron-air fuel cell (IAFC). The integration of simulated solar light irradiation with IAFC could enhance the oxidation capacity, yield of iron ions and power density output. The highest total phosphorus (TP) removal efficiency (approximately 100%) could be obtained at pH 4.0 owing to the synergistic action of coprecipitation and oxidation of EDTMP to orthophosphate (o-PO4), accompanying the optimum power density of 2459 mW m−2 at 2086 mA m−2. The OH mediated oxidation and photodegradation of Fe(III)-EDTMP complex via ligand-to-metal charge transfer reaction worked together to transform EDTMP into o-PO4. In the precipitate, the immobilized phosphorus existed mainly in the forms of organic phosphorus and o-PO4. The presence of oxalic and citric acid enhanced the yield of OH, but the formation of soluble Fe(III)-carboxylate complexes negatively affected the TP removal due to the decreased precipitation capacity. Contrastly, the observed decrease in TP removal caused by humic acid was ascribed to its scavenging effect toward OH. In general, this study proposed an energy efficient and environmental friendly approach for mitigating the potential risk of phosphonates to environmental safety.

Expression of Bacillus ginsengihumi M2.11 bacterial phytase by recombinant Pichia pastoris strains

Phytic acid is the main storage form of organic phosphorus. Due to its structural features, phosphorus in phytate is inaccessible for assimilation by animals. Moreover, remaining inaccessible reservoir of phosphorus for animal nutrition, phytic acid is capable of forming insoluble complex salts, which lead to soil and water pollution. Мicrobial enzymes - phytases, capable of decomposing phytic acid to organic phosphorus are being used as feed additives in animal nutrition to solve this problem. Thus, search and development of technologies for the production of enzymes on an industrial scale are the most urgent. Methylotrophic yeast P. pastoris are widely used in biotechnology, as an efficient system for the recombinant proteins expression. They have many advantages, including rapid growth on inexpensive media, a wide range of molecular tools for genetic manipulation in optimizing production processes, they are safe for humans and animals, carry-out many post-translational modifications and produce recombinant proteins intracellularly or extracellularly within a short period of time. It was found that the recombinant P. pastoris strains pPINK-LC-α-MF -phyC, pPINK-HC-α-amyl -phyC, pPINK-LC-α-amyl -phyC, pPINK-HC-α-MF -phyC are able to produce and to secrete B. ginsengihumi bacterial phytase M 2.11 phyC. The maximum activity was observed in the pPINK-LC-α-MF strain – 2.6 (U / mg). Recombinant B. ginsengihumi M 2.11 phytases exhibited high activity in a wide pH range from 2.5 to 9.0. The MF-phyC-HC construction is pH stable. The temperature optimum of all recombinant phytases corresponds to 37 ° C; recombinant phytases retain their activity in the range from -80 to 90C.

A 2000-year record of phosphorus forms and accumulation in peatland of the Greater Khingan Mountains in Northeast China: Paleoenvironmental implications

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-Po, 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-Po, 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 Po, and reduced inactive Po/Pi at the same time. Fire events could also leave geochemical evidence on peat. It is necessary to consider the both changes of inactive Po/Pi and organic phosphorus accumulation rate when reflected the fire history by phosphorus in core.

Comparative characteristics of the properties of Halpic Chernozem of the Kursk Region of different land use

Analytical data show that prolonged extensive agricultural use of typical Chernozem of Kursk region (Haplic Chernozem) results in adverse changes in some soil properties. This primarily concerns the humus content and the structural state of the Chernozem. Under the influence of continuous winter wheat growing (for 54 years) the losses of humus made up 24% of its content in virgin soil. The permanent corn growing (for 54 years) led to humus 32% losses, and under the influence of the bare fallow (for 54 years) – 48%. As a result of mineralization of humus, which is one of the main aggregative agents, water resistance of Chernozem structure has deteriorated. The number of water-resistant aggregates in variants with continuous winter wheat and continuous corn decreased in comparison with virgin soil (by 30% and 39% respectively). In terms of water resistance, the structure of Chernozem was transformed in agrocenoses from “extremely high” to “good”. Under the influence of the bare fallow the content of water-resistant units decreased by 75%, and the structure became “non-water resistant”. At the same time, the average diameter of waterproof aggregates decreased 2.8, 3.6 and 4.8 times in variants with continuous winter wheat, corn and permanent bare fallow, respectively, whereas the content of the water peptized clay increased 2.8–4.7-fold, and pH of medium increased by 0.16–0.57. At the same time, the content of soil exchangeable calcium reduced (more than 1.1-fold), as well as hydrolytic acidity (1.1–1.7-fold), the content of organic forms of phosphorus (1.1–1.4-fold) and the ratio of organic forms of phosphorus to mineral ones also decreased 2.1–4.1-fold. When the bare fallow is transferred to the abandoned land, the properties of Chernozem vary with different intensity. The most significant changes occurred with water-resistant aggregates. Their content has increased by 53% over 20 years, and the structure has transformed from “non-water resistant” to “good”, while the content water peptized clay has decreased 2.1 times. During the 20-year period, the content of exchangeable calcium and hydrolytic acidity increased by 1.9 and 1.03 mg-eq/100 g of soil. The content of humus has increased by 0.78%, i. e. humus content restoration occurred with a speed of only 0.04% per year. It is necessary to consider this factor when regulating the humus status of the plowed and eroded soils. In general, the impact of continuous bare fallow on the properties of Chernozem was so profound that 20 years after its transfer to the category of abandoned lands, the properties of Chernozem, in most cases, have been restored only to the level typical of variants with crop cultivation.

Effect of long-term plant biomass management on phosphatase-producing bacterial populations in soils under temperate grassland

Organic forms of phosphorus (P) account for over half of the total P present in most soils and make a significant contribution to P cycling and plant nutrition through the actions of various plant and microbial phosphatase enzymes. However, not much is known about the bacterial communities harbouring phosphatase genes, either in composition, abundance, or transcriptional activity. Thus a grassland trial was selected that was undergoing long-term management of plant biomass removal/retention. Treatment plots were sampled after 22 years to examine the impact of prolonged nutrient depletion on bacterial communities helping to mediate organic P turnover. Total bacteria, total fungi, alkaline phosphatase (phoD) and the three classes (A, B, C) of non-specific acid phosphatases (NSAPs) were quantified and amplicons of the phoD and NSAP genes were sequenced. Of the genes quantified, class B (CBAP) genes were positively impacted by biomass removal (p < 0.01). Phosphatase gene transcripts generally appeared to increase in the biomass removed plots, but perhaps only weakly differentiated at this one time point. In the removed plots, we identified the class A (CAAP) community as the most significantly differentiated (p < 0.05). This difference was found strongly at the level of the operational taxonomic unit, indicating that changes in composition are reflective of the biomass management. Several key differentiating bacteria were found, many of which shared a closest known identity to Stenotrophomonas spp. Further, Mantel tests also revealed strong associations of NSAP communities CAAP and CCAP to measures of soil biogeochemistry. The findings of this study further support the importance of microbial mediated P cycling and in the contribution of under-studied P cycling enzymes such as bacterial acid phosphatases.

Addition of fructose to the maize hyphosphere increases phosphatase activity by changing bacterial community structure

Organic forms of phosphorus (P) tend to accumulate in soils with long-term fertilization, however they are generally not easily available to crops. Many crop plants are obligately arbuscular mycorrhizal (AM) and AM fungi are known for not being able to produce phosphatases, the enzyme involved in the mineralization of organic P. AM fungi are able to recruit bacteria in the hyphosphere which can produce phosphatases and access organic P. It is thought that fructose produced by AM fungi acts as a signal to select these bacteria. We designed a system to test whether fructose could stimulate phosphatase activity in the maize hyphosphere. The concentration of fructose produced by AM fungi and the large concentration of fructose equivalent to the entire concentration of hyphal exudate carbon, were added. Small concentrations of fructose did not stimulate phosphatase activity in soil, cause shifts in bacterial community structure or select phosphatase producing species. However, at large concentrations of fructose, phosphatase activity was increased and this was associated with a larger bacterial population and a shift in bacterial community structure towards species which specialized in using fructose and glucose for energy metabolism, such as Saccharibacteria. Nevertheless, there was no specific shift towards species which harbored alkaline phosphatase genes and it is suggested that the change in phosphatase activity was due to subtle shifts in the properties of the phosphatases being produced. These results suggest that fructose was unable to act as a signal to select phosphatase producing bacteria in soil, but could act as an energy source to stimulate phosphatase activity by shifting soil bacterial community structure.

Spatial Distribution of Organic Phosphorus in Sediment and Its Environmental Implication in the Upper Stream of Minjiang River

In order to explore the effect of land use pattern on phosphorus distribution and the potential release capacity of stream sediment in the upper Minjiang River, this paper presented organic phosphorus forms and their spatial distribution characteristics of sediments in the upper Minjiang River by using the IVANOFF method and discussing the effects of physicochemical properties of sediments on the distribution of organic phosphorus forms. The results show that:①nitrogen and phosphorus contents of sediments in Jianxi and Shaxi catchments are higher than those in the Futunxi catchment, probably related to the large number of farmland runoff and municipal sewage near the Jianxi and Shaxi catchments and the large forest area around the Futunxi catchment;②contents in the sediments from three catchments and TP contents in the sediments from Jianxi and Futunxi catchments showed the order of upper reaches < middle reaches < lower reaches, which may be caused by the mountainous and forested areas in the upper reaches and the intensive human activities in the middle and lower reaches;③nitrogen phosphorus in sediments of the three catchments were mainly non-active organic phosphorus, which indicated that upper reaches of the Minjiang river were generally less affected by external pollution, and the relative proportion of organic phosphorus in the sediments of different catchments was relatively large, while the change in different sections of the same river was relatively small;④physicochemical properties of sediments had a significant impact on the morphology and distribution of organic phosphorus, among which the effects of organic matter, TP, and TN were the most obvious, but the effects on sediments in different river basins were different. Therefore, to protect the water quality of the upper Minjiang River, it is necessary to strengthen the control of the living and agricultural pollution sources near the catchments.

The efficiency of controlling the phosphorus release from the sediment using calcined modified water purification plant sludge (C-WTPS)

以自主研发的煅烧改性净水厂污泥（C-WTPS）作为污染底泥活性覆盖材料，室内静态模拟实验研究C-WTPS覆盖强度对控制底泥磷释放效果的影响，分析C-WTPS和底泥中不同形态磷含量变化，探讨C-WTPS薄层覆盖对上覆水体中pH、DO和ORP的影响.结果表明，实验历时40天，在底泥TP释放强度为6.25~10.87 mg/（m²·d）时，覆盖强度为0.25、0.50、1.00、1.50和2.00 kg/m²的C-WTPS对TP平均削减率分别为59.68%、75.71%、88.75%、92.42%和96.28%，可见覆盖强度为1.00 kg/m²以上的C-WTPS能控制底泥中90%以上TP释放.C-WTPS吸附的磷主要以无机磷（IP）中的铁铝结合态磷（NAIP）形式存在，有机磷（OP）和钙磷（AP）形式较少.C-WTPS促进了底泥中易释放形态磷迁移到C-WTPS中，并转化较为稳定的形态磷，可见C-WTP覆盖不仅控制了底泥磷释放，而且也削减了底泥磷释放风险.C-WTPS覆盖后，上覆水体中pH开始呈现下降趋势，最终维持在pH=7范围波动；C-WTPS覆盖强度越大，上覆水体pH下降也明显；C-WTPS覆盖改善上覆水体中DO和ORP环境的效果不明显.;In this paper, the self-developed calcined water treatment plant sludge (C-WTPS) was used as an active sediment capping material for contaminated sediments. The static simulation experiment was conducted to study the effect of C-WTPS capping intensity on controlling phosphorus release from the sediment. Changes of phosphorus contents with different forms in the C-WTPS and sediment were analyzed, and the effect of thin-layer capping of C-WTPS on the pH, dissolved oxygen (DO) and oxidation-reduction potential (ORP) in overlying water was also discussed. The results showed that during a 40-day experiment, when the total phosphorus (TP) release intensity of the sediment was 6.25-10.87 mg/(m²·d), the TP average reduction rate of C-WTPS with the capping intensity of 0.25, 0.50, 1.00, 1.50 and 2.00 kg/m² were 59.68%, 75.71%, 88.75%, 92.42% and 96.28%, respectively. It means that C-WTPS with a capping intensity over 1.00 kg/m² could restrain over 90% TP from releasing. The phosphorus adsorbed by C-WTPS mainly exist in the form of iron-aluminum bounded phosphorus (NAIP)which were included in the inorganic phosphorus (IP), but the forms of organic phosphorus (OP) and calcium phosphate (AP) were less. C-WTPS promoted the migration of phosphorus which were easily released into the C-WTPS and turn it into the relatively stable phosphorus. It showed that the using capping material C-WTPS could not only control the release of phosphorus from the sediment but also reduce the potential risk of phosphorus release. During the process of C-WTPS capping, the pH of the overlying water began to decline at first, and maintained to be around 7 in the end. The higher intensity of capping was used, the lower pH in the overlying water was discovered. Although, the effect of improving the overlying water by using covering material C-WTPS in the DO and ORP were not obvious.