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• In-situ formation of MgFe 2 O 4 enhancing the dehydration and decarboxylation of SM. • Stabilization of HMs was obviously increased after MgFe 2 O 4 modified HTC. • P retention rate reached 88% due to the decrease of soluble and exchangeable P. • MFHCs exhibited high Pb(II) and Cu(II) adsorption capacity without any HMs leaching. Hydrothermal carbonization is an efficient technique for the disposal of livestock manure, enabling its harmless treatment, quantity reduction, and resourceful utilization. Co-hydrothermal of modified materials facilitates the production of more valuable carbonaceous materials. However, further exploration is needed to understand their potential impact on the environmental risks associated with livestock manure disposal and the application of products derived from it. Therefore, the carbonization degree, heavy metals stabilization, and phosphorus retention during the hydrothermal treatment of swine manure were systematically investigated in this study under the influence of in-situ formed MgFe 2 O 4. The results revealed that the in-situ formation of MgFe 2 O 4 improved the dehydration and decarboxylation of organic components in swine manure, thereby improving its carbonization degree. Furthermore, both hydrothermal carbonization and MgFe 2 O 4 modified hydrothermal carbonization resulted in an enhanced stabilization of heavy metals, leading to a significant reduction in their soluble/exchangeable fraction and reducible fraction. Phosphorus was predominantly retained in the hydrochars, with the highest retention rate reaching 88%, attributed to the significant decrease in soluble and exchangeable phosphorus fractions facilitated by the in-situ formation of MgFe 2 O 4. Moreover, MgFe 2 O 4 modified hydrochars exhibited remarkable adsorption capacity for Pb(II) and Cu(II) without any leaching of heavy metals. Overall, the findings indicated that the in-situ formation of MgFe 2 O 4 positively influenced the hydrothermal of swine manure, improving certain economic benefits in its practical application. [ABSTRACT FROM AUTHOR]

A 90-day feeding trial was conducted to investigate the effects of phytase supplemented Distiller’s Dried Grains with Soluble (DDGS) based diet on the production performance, tissue composition, nutrient digestibility and activity of anti-oxidant enzymes in the gills of mrigal (Cirrhinus mrigala) juveniles. Six experimental diets were formulated to contain increasing levels of supplemental phytase, 0 (D1), 250 (D2), 500 (D3), 750 (D4), 1000 (D5), and 1250 (D6) phytase (FTU/kg). Each experimental diet was randomly assigned and fed three times daily to triplicate groups of 180 fish. Significant increase in body weight gain and specific growth rate, feed conversion and protein efficiency ratios of groups fed up to 750 FTU/kg were observed. Broken line analysis of Specific Growth Rate showed that the optimal dietary phytase level of mrigal juveniles is 750 FTU /kg or higher than this dose. Results among protein, lipid, moisture, ash and P contents of whole body, muscle, liver and viscera were not significantly different as phytase level increased from 250 FTU/kg to 1250 FTU/kg (D2 to D6). It was concluded that phytase at the rate of 750 FTU /kg is the optimum dose for the enhanced growth in juvenile mrigal.

Phosphorus (P) is a macro-essential element extensively used in agricultural production. Andisols, commonly found in Indonesia, serve as agricultural areas with high, excessive, and continuous organic matter input. However, the propensity of the soil for P leaching poses a potential risk of water pollution and eutrophication in the watershed area. This study aimed to evaluate the impact of the application rate of organic matter, specifically chicken manure, often employed in agricultural activities related to Andisols. The experiment involved observing P sorption, P desorption, P sorption kinetics, and P uptake by wheat (Triticum aestivum) in soil incubated with chicken manure added at various rates of 0, 10, 20, 30, and 40 t ha-1. The incubation stages were conducted for 14 days at room temperature (27°C) and soil moisture was maintained within field capacity. The data collected were analyzed using Langmuir isotherm for P sorption and desorption, and first-order kinetics for P sorption kinetics. The results showed that the chicken manure addition at 10-40 t ha-1 significantly reduced P bonding energy in Andisols, but failed to decrease the sorption maxima value due to accumulated P from previous applications performed. The application of 20 t ha-1 (CM20) of chicken manure was found to be the optimal rate, displaying high P uptake and reduced bonding energy, while rates above 20 t ha-1 showed no significant difference in P uptake and bonding energy levels. Therefore, CM20 was recommended to increase P availability and prevent P movement into water bodies, promoting sustainable agricultural practices.

Volcanic soils are well-known to have a high agronomical value, and in Sumatra, Mt. Kerinci volcanic soils produce one of the highest quality tea and rice. Declining soil organic carbon (C) and high phosphorus (P) retention are two main issues in volcanic soils in the area. Thus, this study aimed to study the dynamic of C) and P content in volcanic soils and to find the main controls of their variation from geochemical signatures. The soils of Mt Kerinci present a unique environment as one part of the area was converted from forest to tea plantation for about 100 years, and a nearby field had been used for paddy rice cultivation for about 200 years. The study was conducted in the Mt Kerinci area covering 5,922 ha in the north comprise of paddy soils (ps) and north tea soils (nts) and the south slope (south tea soils= sts). Soil samples were collected on a grid of 500 × 500 m under tea and paddy (n = 206 samples) at 0–20 and 20–40 cm depth. All soils have similar pH in H2O, but pH in KCl paddy soils (ps) > north tea soils (nts) > south tea soils (sts). The average content of soil organic Carbon (SOC) in paddy soils was 50% less than in the soils of tea plantations. The labile organic carbon content in paddy soils were lower than in soils of tea plantations. Most C was chemically bound to the metal complex. Higher P retention occurred in all soils. The CaO/TiO2 index indicated a weathering sequence of ps > nts > sts. Soil weathering controlled P retention with an increasing P retention as the soils weathered. Overall, the study suggests that cultivation in volcanic soils influenced the geochemical properties of the soils and subsequently their C and P contents. [ABSTRACT FROM AUTHOR]

A 90-day feeding trial was conducted to investigate the effects of phytase supplemented Distiller's Dried Grains with Soluble (DDGS) based diet on the production performance, tissue composition, nutrient digestibility and activity of anti-oxidant enzymes in the gills of mrigal (Cirrhinus mrigala) juveniles. Six experimental diets were formulated to contain increasing levels of supplemental phytase, 0 (D1), 250 (D2), 500 (D3), 750 (D4), 1000 (D5), and 1250 (D6) phytase (FTU/kg). Each experimental diet was randomly assigned and fed three times daily to triplicate groups of 180 fish. Significant increase in body weight gain and specific growth rate, feed conversion and protein efficiency ratios of groups fed up to 750 FTU/kg were observed. Broken line analysis of Specific Growth Rate showed that the optimal dietary phytase level of mrigal juveniles is 750 FTU /kg or higher than this dose. Results among protein, lipid, moisture, ash and P contents of whole body, muscle, liver and viscera were not significantly different as phytase level increased from 250 FTU/kg to 1250 FTU/kg (D2 to D6). It was concluded that phytase at the rate of 750 FTU /kg is the optimum dose for the enhanced growth in juvenile mrigal. [ABSTRACT FROM AUTHOR]

The effect of organic matter (OM) on soil phosphorus (P) sorption is controversial, as there is still no clear answer whether organic matter inhibits or increases P sorption. Despite the great need for renewable sources of available P and OM in agricultural soils, little is known about the interaction between P and dissolved organic matter (DOM) in natural soil systems. The aim of this research was to uncover if and how soil saturation with DOM derived from different types of abundant agricultural wastes (cattle manure, horse manure, biogas digestate, compost) affects the phosphate sorption. We examined the P sorption process in control and DOM-saturated sandy soils. The results indicated that OM introduced with agricultural waste did not always reduce P sorption, but certainly had an effect on impairing P fixation, and thus, may result in potentially greater P mobility in the soil, including P availability. Among these waste materials, DOM from horse manure had the most positive effect on P mobilization; thus, horse manure—if available—is recommended for spreading on soils with low P mobility. [ABSTRACT FROM AUTHOR]

Phosphorus is a crucial nutrient in terrestrial ecosystems, influencing primary productivity and ecosystem health. However, its retention and cycling vary significantly between eutrophic and dystrophic systems. This paper examines the role of natural composition-specifically soil properties, vegetation types, and microbial communities-in phosphorus retention within these contrasting ecosystems. Eutrophic ecosystems, characterized by high nutrient levels, often experience phosphorus accumulation and potential eutrophication, while dystrophic ecosystems, with low nutrient availability, exhibit limited phosphorus retention and often struggle with nutrient deficiencies. Understanding the natural mechanisms governing phosphorus retention can inform management practices aimed at maintaining ecosystem health and preventing nutrient-related issues. Key factors influencing phosphorus retention include soil texture, organic matter content, pH levels, and the diversity and function of soil microbiota. The study synthesizes current research on these factors and proposes management strategies tailored to the specific needs of eutrophic and dystrophic ecosystems. [ABSTRACT FROM AUTHOR]

The effect of organic matter (OM) on soil phosphorus (P) sorption is controversial, as there is still no clear answer whether organic matter inhibits or increases P sorption. Despite the great need for renewable sources of available P and OM in agricultural soils, little is known about the interaction between P and dissolved organic matter (DOM) in natural soil systems. The aim of this research was to uncover if and how soil saturation with DOM derived from different types of abundant agricultural wastes (cattle manure, horse manure, biogas digestate, compost) affects the phosphate sorption. We examined the P sorption process in control and DOM-saturated sandy soils. The results indicated that OM introduced with agricultural waste did not always reduce P sorption, but certainly had an effect on impairing P fixation, and thus, may result in potentially greater P mobility in the soil, including P availability. Among these waste materials, DOM from horse manure had the most positive effect on P mobilization; thus, horse manure—if available—is recommended for spreading on soils with low P mobility.

Costadone L, Sytsma MD. 2022. Effect of alternative regional urban growth scenarios on a major urban lake. Lake Reserv Manage. 38:228–239. Land use management decisions developed at the regional scale that are intended to optimize environmental quality could have negative results at a local scale. We downscaled 3 regional urban growth scenarios (low, medium, and high land conversion) to a watershed scale and assessed how different regional land-use scenarios can impact important ecosystem services provided by a major urban lake. The scenario that depicted a low land conversion and concentrated future urban growth within an urban growth boundary at the regional scale resulted in a high-density development in the area surrounding the lake at the watershed scale. This type of development resulted in an increase of more than 30% in external phosphorus input to the lake compared to current conditions. Higher external phosphorus input will likely lead to water quality deterioration, with detrimental consequences for the ecosystem services provided by the lake. Our model forecasted a reduction of 3 to 4 m in lake water transparency, which will diminish recreational benefits provided by the lake and degrade wildlife habitat. In the next decades, population growth and land conversion will likely cause the resurgence of serious eutrophication symptoms. The reinforcement of nutrient management practices in the lake watershed will be necessary to offset the negative impact of urbanization from regional scale planning. Land-use policies developed at regional scales should consider trade-offs that impact highly valued local sources of ecosystem services. [ABSTRACT FROM AUTHOR]

Simple Summary: Phosphorus (P) is an essential mineral in the diets of pigs. The degree to which P is utilized has both economic and environmental consequences to the swine industry. Mathematical models can be used to describe the relationship between P intake and P retention. These models provide information regarding P utilization that can be used to formulate diets aimed at reducing P overfeeding, and therefore decrease P wastage. The objective of this study was to assess the ability of four non-linear models (monomolecular, Michaelis-Menten, Richards, and Morgan) and one simple linear model to describe the relationship between P intake and P retention in growing and finishing pigs. Through fitting these models to data from P balance studies, non-linear models which describe diminishing returns type behaviour, the monomolecular and the Michaelis-Menten models, were found to best describe the relationship between P intake and P retention in these categories of pig. The parameter of these models allows estimates of endogenous P losses, P requirement for maintenance and theoretical maximum P retention enabling the more efficient use of P in the swine industry. The ability of four non-linear mixed models and one linear mixed model to describe phosphorus (P) retention as a function of dietary P intake, expressed on an available P (avP) basis, was assessed in growing and finishing pigs. Of the four non-linear models, the monomolecular and Michaelis-Menten describe diminishing returns behaviour, while the Richards and Morgan describe sigmoidal behaviour with the ability to also describe diminishing returns. Using a meta-analysis approach, models were fitted to avP intake vs. P retention data from P balance studies. Pig bodyweights (BW) ranged from 43.5 to 133 kg, P intake ranged from 0.055 to 0.468 g kg−1 BW0.75 d−1 for avP, and 0.151 to 0.806 g kg−1 BW0.75 d−1 for total P, with P retention ranging from 0.026 to 0.329 g kg−1 BW0.75 d−1. Models were evaluated using statistical measures of goodness-of-fit and inspection of residuals. The monomolecular and Michaelis-Menten best described the relationship between P retention and P intake. Endogenous P losses and P requirement for maintenance were found to be higher in finishing pigs compared to growing pigs as BW increased. [ABSTRACT FROM AUTHOR]

Nearly all of the wetlands in the coastal zone of Lake Erie have been degraded or destroyed since the 1860s, and most of those that remain are separated from their watersheds by earthen dikes. Hydrologic isolation of these wetlands disrupts ecosystem benefits typical to Great Lakes coastal wetlands, particularly the ability to trap sediments and retain nutrients when inundated by runoff and lake water. High-frequency measurements of turbidity and discharge were taken in 2013 and 2014 to observe turbidity and water flow dynamics to estimate total phosphorus flux of a hydrologically reconnected diked wetland pool in the Crane Creek-Lake Erie wetland complex. Modeled estimates suggest the reconnected pool retained 8% of the total phosphorus loading in 2013 and 10% in 2014, which included short periods of phosphorus export to Lake Erie. Water flowing out of the wetland generally had lower turbidity than inflowing water, but flux in and out of the pool varied seasonally and was linked to changes in lake-levels, seiche dynamics, and weather conditions. More frequent storms, higher winds, and stronger seiches in the spring and fall created turbidity patterns that suggest more phosphorus retention than in summer or winter. Estimates suggest that phosphorus was released during the summer when higher lake levels and the absence of frequent storms, larger short-term seiche oscillations, and potentially soil oxygen availability were driving flux dynamics. This study demonstrated that reestablishing lake hydrology through reconnection of wetland pools can reduce loading and alter timing of delivery of total phosphorus to Lake Erie. [ABSTRACT FROM AUTHOR]

Natural apatites have previously shown a great capacity for phosphate retention from wastewater. However, its fine particle size distribution may lead to a premature clogging of the filter. Accordingly, a granulated apatite product was developed and manufactured in order to control the particle size distribution of the media. Experiments were conducted on laboratory columns to assess their phosphorus retention capacity, to identify the processes involved in phosphorus retention and to evaluate their kinetic rates. The results showed phosphorus retention capacities of 10.5 and 12.4 g PO4-P·kg−1 and kinetic rate coefficients in the range of 0.63 and 0.23 h−1 involving lower values than those found for natural apatites in previous studies. Scanning Electron Microscopy images showed that apatite particles in the granules were embedded in the binder and were not readily accessible to act as seeds for calcium phosphate precipitation. The retention processes differ depending on the supersaturation of the solution with respect to calcium phosphate phases: at low calcium concentrations (69.8 ± 3.9 mg·L−1), hydroxyapatite precipitates fill up the porosity of the binder up to a depth of 100–300 μm from the granule surface; at higher calcium concentrations (112.7 ± 7.4 mg·L−1) precipitation occurs at the granule surface, forming successive layers of hydroxyapatite and carbonated calcium phosphates.

ABSTRACT: The study aimed to determine the ileal phosphorus (P) digestibility (iPD) and the excreta P retention (ePR) of 5 monodicalcium phosphate (MCP) samples and 3 dicalcium phosphate (DCP) samples in broiler chickens and in Pekin ducks using the substitution method. A total of 720, 21-d-old Arbor Acres broiler chickens in experiment 1 and 720, 15-d-old Pekin ducks in experiment 2 were randomly allocated to 9 dietary treatments with 8 replicate cages (10 birds/cage) based on the similar mean body weight, respectively. The collection of excreta (for 72 h after a 3-d acclimation) and ileal digesta (after 6 d of feeding experimental diets) was done. The results showed the average iPD/ePR of MCP and DCP for broilers were 83.11%/74.52% and 75.34%/69.46% and for ducks were 79.37%/80.02% and 75.74%/76.44%, respectively. The iPD/ePR of MCP in broilers and the ePR of MCP in ducks were markedly higher (P < 0.05) than those of DCP. Our data suggest that using the substitution method to evaluate the bioavailability of feed phosphates has its own advantages; MCP has higher biological availability than DCP for broilers and ducks.

Iron (Fe) cycling exerts strong control on the mobility and bioavailability of the key nutrient phosphate (PO 4) in soils and sediments. Coprecipitation of PO 4 is known to alter the structure of Fe (oxyhydr)oxides (FeOx), however the environmental fate of PO 4 -bearing FeOx is not well-understood. Here, PO 4 -bearing FeOx with 9 mol% coprecipitated PO 4 were prepared by Fe(III) hydrolysis and Fe(II) oxidation in the presence of dissolved PO 4 , in addition to pure FeOx synthesized in PO 4 -free solutions. The pure and PO 4 -bearing FeOx were subsequently exposed to different concentrations of dissolved Fe(II) and sulfide (2 and 10 mmol L−1). Mineral transformations and the fate of PO 4 were tracked over 7–14 days with wet chemical techniques (including sequential Fe and S extraction) and synchrotron-based Fe K-edge X-ray absorption spectroscopy. Coprecipitation of PO 4 affected the rate and extent of FeOx transformation differently for Fe(II) and sulfide. Poorly-ordered PO 4 -bearing FeOx was preserved in the presence of dissolved Fe(II) while pure ferrihydrite was nearly completely transformed into goethite over 7 days. By contrast, coprecipitation of PO 4 rendered FeOx more reactive towards sulfide compared to pure FeOx. Reaction with dissolved sulfide resulted in the formation of non-sulfidized Fe(II) or Fe(II) sulfide under high and low Fe/sulfide ratio, respectively. Under low Fe/sulfide ratio, Fh and PO 4 -bearing, poorly-ordered FeOx were nearly completely sulfidized after 14 days. Sulfidation of FeOx led to efficient release of PO 4 into solution, and at low Fe/sulfide ratio more PO 4 was released than expected based on the extent of Fe sulfidation. The results suggest feedback mechanisms of environmental relevance: coprecipitation of strongly-sorbing species such as PO 4 disrupts FeOx structure, which affects FeOx reactivity and the overall nutrient or contaminant retention capacity of soils or sediments differently depending on the ambient redox conditions. Specifically, the switch from reducing to sulfidic conditions may be associated with the disproportionate release of nutrients and contaminants. [ABSTRACT FROM AUTHOR]

Biochar application can reduce losses of runoff from rainfall and increase phosphorus retention on sloping farmland. However, high application rates and high mobility of biochar present a challenge to the ecological environment, emphasizing the need for innovative solutions. This study investigated the potential benefits of applying nano-biochar (NBC) in combination with different crops on sloping farmland. Sloping plots were amended with varying mass contents of NBC (0.1, 0.5, 0.7, 1.0, and 0.0% as the control) by band application and planted with various crops (caragana, alfalfa, soybean, and maize). Simulated rainfall was applied 40–100 min to each plot and the runoff, sediment, and available phosphorus were collected. The results indicated that NBC application could improve rainfall interception on sloping soil by 18.08–31.14% and reduce cumulative runoff and sediment by 10.88–31.75%. With increasing applications of NBC, most of available phosphorus was retained in the soil, and available phosphorus losses were reduced by 22.90–43.01% compared with the control. The 1.0% NBC application and alfalfa combination showed the greatest combined effect in reducing rainwater runoff and phosphorus loss. The combination of crops and NBC application was an effective solution for preventing sediment and phosphorus loss caused by rainfall on sloping farmland. [ABSTRACT FROM AUTHOR]

This special issue of Ecological Engineering provides an overview of research within the Everglades Stormwater Treatment Areas (STAs) over the past decade to understand the ecology and the biogeochemical processes that affect phosphorus (P) retention in these constructed wetlands. This research was established within the South Florida Water Management District's Restoration Strategies Science Plan (RSSP). The RSSP was developed in 2012, updated in 2018, and produced a total of 21 studies. The goal of RSSP research is improve understanding of the factors contributing to P retention, to support management of the STAs to attain and sustain a stringent outflow total P concentration goal (i.e., the Water Quality Based Effluent Limit or WQBEL) and to maintain the wetland plant communities used to achieve this goal. Compliance with the WQBEL will reduce P loads to the Everglades to support restore and maintain this special ecosystem. This synthesis paper presents an overview of the STAs and their purpose and then summarizes the findings from the publications included in this special issue as well as previous STA related research. From this synthesis, a list of potential management options to enhance P retention in the STAs is presented. • Stormwater Treatment Areas (STAs) built to reduce P in runoff entering the Everglades. • STA discharge must meet strict low P concentration limits. • P biogeochemistry research conducted to support management of the STAs. • P removed by particle settling, biogeochemical processes and plant uptake. • Fauna excretion, bioturbation, and internal loads substantially affect P retention. [ABSTRACT FROM AUTHOR]

Phytase, a widely used feed additive in poultry diets, increases P availability and subsequently reduces inorganic-P supplementation and P-excretion. Phytase supplementation effect on P-retention in poultry has been investigated, but the effect sizes were highly variable. The present study's objective was to conduct several meta-analyses to quantitatively summarize the phytase effect on P-retention in broilers and layers. Data from 103 and 26 controlled experiments testing the phytase effect on P-retention were included in 2 separate meta-analyses for broilers and layers, respectively. The mean difference calculated by subtracting the means of P-retention for the control group from the phytase-supplemented group was chosen as an effect size estimate. Between-study variability (heterogeneity) of mean difference was estimated using random-effect models and had a significant effect (P < 0.01) in both broilers and layers. Therefore, random-effect models were extended to mixed-effect models to explain heterogeneity and obtain final phytase effect size estimates. Available dietary and bird variables were included as fixed effects in the mixed-effect models. The final broiler mixed-effect model included phytase dose and Ca-to-total-P ratio (Ca:tP), explaining 15.6% of the heterogeneity. Other variables such as breed might further explain between-study variance. Broilers consuming control diets were associated with 48.4% P-retention. Exogenous phytase supplementation at 1,039 FTU/kg of diet increased P-retention by 8.6 percentage units on average. A unit increase of phytase dose and Ca:tP from their means further increased P-retention. For layers, the final mixed-effect models included dietary Ca, age, and experimental period length. The variables explained 65.9% of the heterogeneity. Layers receiving exogenous phytase at 371 FTU/kg were associated with a 5.02 percentage unit increase in P-retention. A unit increase in dietary Ca from its mean increased P-retention, whereas an increase in the experiment length and layer's age decreased P-retention. Phytase supplementation had a significant positive effect on P-retention in both broilers and layers, but effect sizes across studies were significantly heterogeneous due to differences in Ca contents, experiment length, bird age, and phytase dose.

An 8-weeks feeding trial was conducted to evaluate the effects of different dietary phosphorus (P) levels on growth performance, P concentrations in tissue, haemolymph biochemistry and hepatopancreatic metabolic enzyme activities for juvenile swimming crab (Portunus trituberculatus). Five semi-purified diets (46 % protein, 7.5 % lipid) were formulated to contain different P levels of 6.4, 10.8, 16.2, 21.0 and 25.7 g kg−1, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile swimming crab (initial weight was 12.82 ± 0.15 g) that were reared in single crab unit. The results indicated that percent weight gain (PWG) were significantly influenced dietary P levels, the highest PWG were observed in crabs fed the diet containing 16.2 and 21.0 g kg−1 P. Moreover, P contents in muscle, hepatopancreas and carapace significantly increased with dietary P levels increasing from 6.4–21.0 g kg−1. P retention rate (PRR) in hepatopancreas and muscle significantly decreased with dietary P levels increasing from 6.4 to 25.7 g kg-1. Furthermore, dietary deficient P (such as 6.4 and 10.8 g kg−1 P) levels reduced ATP content, activities of PK and SDH in hepatopancreas. Crabs fed the diet with 6.4 g kg−1 P also showed significantly lower expression of genes involved in electron transport chain complex, such as nd1, sdhc and coxIII in hepatopancreas than those fed the other diets. The expression of genes related to mitochondrial energy metabolisms, such as Atpase6, sirt1, and nrf1 in hepatopancreas were significantly up-regulated in crabs fed 16.2 and 21.0 g kg−1 P diets. Overall, based on the two slope broken-line and quadratic regression analysis of PWG against the dietary total P levels, the optimum dietary P requirement was estimated to be 15.91 and 16.83 g kg−1, respectively.

Context: Reducing the environmental impact of animal production is becoming a really hot topic, especially with raised concerns over excessive flows of nitrogen and phosphorus (P) to the environment. Aims: The present study was conducted to determine the effects of phytase supplementation on growth, plasma biochemistry, bone mineralisation and P utilisation of pre-lay pullets fed varying levels of non-phytate P. Methods: A total of 240 Lohmann pullet chicks were randomly allocated to one of six dietary treatments with eight replicate cages (5 birds per cage) per treatment. Six treatments included three phytase-free diets and three diets supplemented with 1000 U/kg phytase; the non-phytate P levels were 2.75-2.50-2.25, 3.75-3.50-3.25 and 4.75-4.50-4.25 g/kg in the former, and 1.75-1.50-1.25, 2.75-2.50-2.25 and 3.75-3.50-3.25 g/kg in the latter, for the age of 0-4, 4-8 and 8-16 weeks respectively. Key results: No significant differences were found for growth performance, plasma biochemistry (calcium, P, alkaline phosphatase and albumin) and bone mineralisation among dietary treatments, but P retention (%) was different (P < 0.001). Analysis of planned contrasts showed that phytase supplementation increased phytate P retention (P < 0.001), and improving the utilisation of phytate P tended most efficiently under low P conditions. Total P retention rate was reduced slightly by phytase supplementation (P < 0.05). Conclusions: The results indicated that dietary non-phytate P level could possibly be reduced to 1.75, 1.50 and 1.25 g/kg for 0-4, 4-8 and 8-16 weeks of age respectively after phytase supplementation, without compromising pullet growth and performance during the pre-laying period. Implications: The results of this study will contribute to decreasing P excretion by poultry and reducing the potential environmental impact with land application of manure. [ABSTRACT FROM AUTHOR]

To determine whether buckwheat phytase can be used as an alternative phytase source, growth performance, bone quality and P retention were measured in broilers given non-phytate P-deficient diets. Non-germinated (BU) and germinated (GBU) buckwheat were used: they were ground and sieved to remove hulls before use. A total of 120 male broiler chicks (8 d of age) were divided into 8 groups (15 birds each) and given one of the following 8 diets until 42 d of age: positive control (PC) diet satisfying recommended level of all nutrients, negative control (NC) diet formulated to contain 0.16% lower non-phytate P than PC diet, and six other diets, formulated by replacing maize in NC diet with BU or GBU at 10%, 15% and 20% concentrations. Starter diets contained 23.5% crude protein (CP) and 3,200 kcal of ME/kg, and were used for 8–21 d of age. Then, grower diets with 20.5% CP and 3,250 kcal of ME/kg, and were provided for 22–42 d of age. Compared with the PC group, NC group showed impaired growth performance (BW gain, FI, and FCR), and bone quality (dry weight, breaking strength and contents of ash and P in tibia). However, in most cases, these impairments were ameliorated dose-dependently by the addition of BU and GBU in diets, and the restoration magnitude was greater in GBU than in BU treatment. Total P excretion decreased in NC group and further decreased dose-dependently with increasing levels of BU and GBU. Except for the values in PC group, total P retention increased as the total P excretion decreased. In conclusion, dietary BU and GBU restored the growth performance and bone quality impaired by the P deficiency, and improved P retention in broilers, which suggested that buckwheat, especially when germinated, can be used as an alternative phytase source in broiler diets.

Constructed wetlands (CWs) are one of the main countermeasures to reduce diffuse phosphorus (P) losses, but there is still a lack of systematic guidance accounting for spatially variable effects of hydraulic and P load on P retention. We present a three-step modelling approach for determining suitable placement of CWs in four different size groups (0.1–1.0 ha), based on incoming hydraulic and P load. The modelled hypothetical CW area was only 17% of that previously estimated and area of efficient CWs is even lower. The mean area-specific P retention increased with CW size. However, the spatial variation in retention was large for all size groups and largest (6–155 kg ha−1 year−1) for the smallest CWs due to highly variable incoming P loads, showing the possible benefits of targeted placement of CWs. The presented modelling approach has also flexibility to include and account for possible future changes in land cover and management. [ABSTRACT FROM AUTHOR]

Drainage ditches are effective agricultural facilities because they can drain excess water from the field, and an eco-friendly drainage ditch can also eliminate agricultural nonpoint source pollution effectively. Field work has been conducted in four types of drainage ditches with different revetment techniques, i.e., a two-stage ditch with a woodpile bank, a single trapezoidal ditch with a geotextile bag, a hollow hexagonal brick, and a reinforced vegetative bank revetment. The corresponding retention capacity of phosphorus in these ditches has been investigated. Results show that two-stage ditches can retain dissolved phosphorus (DP) more effectively compared to the other three single trapezoidal drainage ditches, and the retention efficiency is as high as 60%. The concentration of total suspended sediment (TSS) is positively correlated with that of total phosphorus (TP), and the retention capacity of drainage ditches on phosphorus will decrease as discharge increases. Current work proves that a well-designed two-stage section ditch can effectively eliminate the nonpoint source pollution during practical agriculture drainage application. [ABSTRACT FROM AUTHOR]

Contemporary land use can affect sediment nutrient processes in rivers draining heavily modified watersheds; however, studies linking land use to sediment nutrient processes in large river networks are limited. In this study, we developed and evaluated structural equation models for denitrification and phosphorus retention capacity to determine direct and indirect linkages between current land use and sediment nutrient processes during base flow in the Fox River watershed, WI, USA. A large spatial‐scale dataset used for this study included sediment nitrogen and phosphorus retention measurements and land use information for 106 sites. The structural equation models for the Fox River watershed identified direct links between current land use and in‐stream sediment nutrient processes. Subwatersheds with agricultural land consisting of more natural land cover had lower surface water nitrate concentrations and higher denitrification enzyme activity than subwatersheds with less alternative cover. This indicates that best management practices implemented in the Fox River watershed that restore natural land cover can improve water quality through nitrogen removal on the agricultural landscape and in the river network. Best management practices are not having the same measurable effects on phosphorus in the river network, most likely due to legacy phosphorus stored in the sediment. Key Points: Structural equation modeling of the Fox River Basin illustrates direct land use effects on river channel sediment nutrient dynamicsAgricultural best management practices that restore natural land cover have a small differential effect on sediment nutrient dynamicsFuture scenarios modeling suggests current land management actions have a minimal effect on sediment nutrient dynamics [ABSTRACT FROM AUTHOR]

Taurine is a component that tends to be deficient in fish diets that contain higher plant‐derivative proteins. Acanthopagrus schlegelii juveniles (IBW − 11.28 g) were fed nine diets containing SPC levels (SPC40, SPC60, SPC80 and SPC100), or supplemented with 5 g/kg of taurine at each replacement level. Our results showed higher WGR and SGR in SPC60 + TAU (WGR; 224.67, SGR; 2.10) followed by SPC40 + TAU (WGR; 221.75, SGR; 2.09). Phosphorus retention efficiency was significantly raised as the SPC increased when compared with the control diet. Taurine addition showed an incline in the nitrogen retention efficiency. An effect was observed within FR between fish and the SPC content. ADCs of dry matter, crude lipid and phosphorous were affected by SPC, while taurine addition affected only crude lipid. A significant effect was seen in ash and phosphorus by the SPC and taurine. TAU supplementation showed an increased T‐AOC activity in the SPC80 + TAU (1.90), while malondialdehyde and catalase activity were reduced except in completely replaced fish meal groups. It could be concluded that black sea bream can accept the substitution of FM with 60% of SPC while at the inclusion of dietary TAU (5 g/kg) growth could be improved. [ABSTRACT FROM AUTHOR]

Surface runoff from agricultural fields is the largest non-point source of phosphorus (P) that pollutes surface water in humid temperate regions. Best management practices have attempted to reduce P loading and improve P retention in agricultural soils, but significant losses continue to occur, emphasizing the need for novel solutions. The objective of this study was to determine whether wood-based biochars applied to an agricultural field, 3 years earlier, could reduce P loss in surface runoff by increasing water infiltration or by improving soil stability. Field plots amended with Dynamotive, Basques and Pyrovac biochars (5 and 10 t ha−1) or without biochar were subjected to 30-min of simulated rainfall to determine runoff volume, time-until-ponding, infiltration rate, and water holding capacity, as well as the P concentration and P load in runoff. The distribution of soil macro- and micro-aggregates and their total organic C and total P content was measured. Soil water dynamics were not affected by biochar amendments, however, runoff contained significantly less ortho-P in field soil amended with Dynamotive and Basques biochar at 5 t ha−1 and significantly less particulate P when amended with biochar at 10 t ha−1. Biochar-amended soil had significantly greater microaggregate stability, organic C and total P content than the control soil without biochar. The reduction in particulate P concentration in runoff may be the result of biochar integration within the microaggregate structure, which indirectly promotes P retention in macroaggregates. • Biochar amendment reduces the P loss in surface runoff from field soil. • Soils amended with biochar had greater microaggregate stability. • Macroaggregates from biochar-amended soils contained higher total P content. • Biochar may increase P integration into the soil microaggregate structure. [ABSTRACT FROM AUTHOR]

Rivers affected by anthropogenic nutrient inputs can retain some of the phosphorus (P) load through sediment retention and burial. Determining the influence of land use and management on sediment P concentrations and P retention in fluvial ecosystems is challenging because of different stressors operating at multiple spatial and temporal scales. In this study, we sought to determine how land use and management influenced sediment P concentrations and P retention within a river network draining a watershed modified by mixed land use activities, the Fox River, Wisconsin, USA. Results show that current land use had no detectable effect on sediment P concentrations and only a small potential effect on P retention capacity. However, sites draining predominantly forested areas were associated with riverbed sediments less saturated in P, whereas sites draining mainly agricultural areas were more likely to release sediment‐bound P. Current management actions, including the implementation of best management practices, had a small positive effect on P retention capacity but had no observed effect on sediment P concentrations. Our results suggest that fine riverbed sediment throughout the Fox River network is saturated with P and has the capability to release P when water column P concentrations are low. These P‐saturated riverbed sediments represent a potential legacy effect of past land use disturbances on P dynamics in the Fox River network. Plain Language Summary: Agriculture and urbanization unintentionally cause phosphorus, a key plant nutrient, to be lost to streams and rivers. Higher concentrations of phosphorus can lead to harmful algal blooms in rivers and lakes. River sediment is potentially able to temporarily remove some of this phosphorus by long‐term burial. In this study, our objective was to determine how land use affects the ability of the sediment to remove the phosphorus. We studied the Fox River watershed in eastern Wisconsin, USA, which contains agriculture, urban, forest, and wetland areas. We expected more phosphorus to be stored in urban and agricultural areas. Instead, land use had little effect on the capacity of the sediment to remove phosphorus from the river water. The sediment throughout the watershed already seemed to be storing a lot of phosphorus, even in areas that were forested. The buried phosphorus potentially can be released to the water column if conditions in the river change. Thus, the river sediment in this watershed may contribute to water quality problems in the future. Key Points: Fine sediments were saturated with phosphorus throughout the Fox River Basin and have potential to release phosphorus when water column concentrations are lowCurrent land use had no detectable effect on sediment phosphorus concentration and small potential effect on sediment phosphorus retentionBest agricultural land management practices had a small positive effect on sediment phosphorus retention capacity [ABSTRACT FROM AUTHOR]

The objective of this study was to analyze the influence of periphyton biofilm on nutrient releases from sediments in ponds and lakes. The physico-chemical parameters in the overlying water, the TP content, and the P forms in the sediments and periphyton biofilm were measured. The results showed that (1) periphyton biofilm could change the physico-chemical indexes in the overlying water; furthermore, the periphyton biofilm influenced the release of N and P from sediments, and its extent of influence was closely related to the nutrient levels of the sediments. (2) The periphyton biofilms effectively reduced the concentrations of N and P in sediments with different nutritional levels (P < 0.05). The average daily TN removal rates were 52% and 25% in the pond and lake microcosms, respectively, and the average daily TP removal rates were 1.06% and 20.9% in the pond and lake microcosms, respectively. This result suggested that periphyton biofilms acted as biological buffers for nutrient cycling between sediments and overlying water; these buffering effects were mainly through the absorption, filtration, and precipitation of nutrients. (3) The TP content and P forms of the periphyton biofilm were different between the pond and lake microcosms, which indicated that the P forms of the periphyton biofilm were potentially influenced by the nutritional levels of the sediments. Article Highlights: There are different in the influence of periphyton biofilm on nutrient releases from sediments in ponds and lakes. Periphyton biofilm could change the physico-chemical indexes in the overlying water; furthermore, the periphyton biofilm influenced the release of N and P from sediments, and its extent of influence was closely related to the nutrient levels of the sediments. The TP content and P forms of the periphyton biofilm were different between the pond and lake microcosms. [ABSTRACT FROM AUTHOR]

H 2 SO 4 -modified biochar has been recognized as a means to achieve the advantages of carbon sequestration, and nitrogen loss reduction. However, little information is available on its effect on phosphorus (P) uptake, soil available P, and P leaching under alternate wetting and drying irrigation (I AWD). A split-plot experimental layout was carried out with two irrigation regimes (conventional continuous flooding, I CF , and alternate wetting and drying, I AWD) as main plots and three biochar additions (biochar-free control, B 0 , non-acidified biochar, B 20 , and acid-modified biochar, B 20A) as subplots. Results indicated that I AWD decreased water percolation by 9.26%–14.74% and P leaching by 50.14%–106.64% and increased surface soil available P by 10.88–29.08%, resulting in 14.21–35.03% apparent phosphorus balance (APB) over the three years as compared with I CF. B 20 produced a 6.23% lower grain yield in the 1st year and 5.06% and 11.02% higher yields in the 2nd and 3rd years, while B 20A increased or tended to increase it throughout the three years. Both B 20 and B 20A significantly decreased total water percolation (9.68–28.37%), P leaching (18.26–152.00%), and increased soil available P (9.90–46.24%), dissolved P in surface soil (10.00–62.50%), and P uptake (4.31–49.71%), and thereafter enhanced apparent phosphorus balance (11.06–40.78%). Compared with B 20 , B 20A achieved a better APB due to a 113% lower P leaching and 52.9% lower dissolved P at 60 cm soil profiles. I AWD B 20A-M produced the highest APB, surface soil available and dissolved P, and the lowest P leaching, which increased grain yield, APB, surface soil available P, and dissolved P by 9.54%, 129.61%, and 53.19%, and decreased P leaching by 257% over I CF B 0 , respectively. Therefore, the use of H 2 SO 4 -modified biochar could produce higher grain yield with lower P leaching and higher APB for I AWD paddy systems, which is beneficial to enhancing plant P uptake, mitigating P leaching, and ensuring sustainable agricultural production. [Display omitted] • Alternate wetting and drying irrigation (I AWD) reduce water use and P leaching. • One-year field-aged biochar reduced P leaching, improve P retention and plant uptake. • Acid-modified biochar (B 20A) enhanced soil available P and rice grain yield. • I AWD B 20A give positive apparent P balance and prevent soil P depletion. [ABSTRACT FROM AUTHOR]

The study was conducted to compare two plant ingredients as dietary protein sources for rainbow trout on the basis of feed acceptability, survival, growth, feed conversion, nitrogen and phosphorus utilization efficiency and loading. Two extruded diets were formulated with the inclusion of a soybean meal (DS) and a lupin meal (DL). The control diet was a fish meal (FM) based diet. All diets were isonitrogenous and isolipidic. Triplicate groups of 65 fish (5.10 ± 0.10 g) were assigned to each diet. At the end of the experiment (66 days), all groups of fish fed diets had a similar final growth and feed utilization efficiency (P > 0.05). Nitrogen retention rate was higher for the group fed the control diet and in consequence the calculated loading amount of this nutrient resulted lower when compared with the test diets. However, phosphorus retention was higher in the groups of fish fed the experimental diets (DL 26.58 ± 0.22 and DS 27.67 ± 3.05) when compared to the control diet (22.08 ± 1.12) (P < 0.05). This represents a phosphorus loading of 8.33 ± 0.23, 8.96 ± 1.02, and 11.55 ± 0.67 kg/t production for the diets DL, DS, and control, respectively. Therefore, the results indicate that lupin meal can be used as a possible plant protein source for the formulation of low-phosphorus loading diets for rainbow trout without affecting feed acceptability and growth performance. This legume represents a clear opportunity to supply the high demand for plant protein sources for aquaculture. Further studies are needed to evaluate and compare different lupin species and varieties.

Coastal wetlands around the Laurentian Great Lakes in North America have the potential to intercept surface water coming off of the landscape and reduce the amount of nutrients and sediment entering the lakes. However, extensive coastal wetland areas have been isolated behind dikes and thus have limited interaction with nutrient-rich waters that contribute to harmful algal blooms and other water-quality issues. In this study, we developed a method to use high-frequency measurements of discharge and turbidity to estimate sediment and total phosphorus retention in a hydrologically reconnected coastal wetland. We found sediment and total phosphorus retention to be episodic and highly related to fluctuations in water level. Low water levels in Lake Erie in late 2012 resulted in low retention in the wetland, but sediment and total phosphorus retention increased as water levels rose in the first half of 2013. Overall, the reconnected wetland was a sink for both total phosphorus and suspended sediment and locally reduced phosphorus loading rates to Lake Erie. Additional wetland reconnection projects have the potential to further reduce phosphorus and sediment loading rates, which could improve local water quality and ecosystem health. [ABSTRACT FROM AUTHOR]

To determine whether buckwheat phytase can be used as an alternative phytase source, growth performance, bone quality and P retention were measured in broilers given non-phytate P-deficient diets. Non-germinated (BU) and germinated (GBU) buckwheat were used: they were ground and sieved to remove hulls before use. A total of 120 male broiler chicks (8 d of age) were divided into 8 groups (15 birds each) and given one of the following 8 diets until 42 d of age: positive control (PC) diet satisfying recommended level of all nutrients, negative control (NC) diet formulated to contain 0.16% lower non-phytate P than PC diet, and six other diets, formulated by replacing maize in NC diet with BU or GBU at 10%, 15% and 20% concentrations. Starter diets contained 23.5% crude protein (CP) and 3,200 kcal of ME/kg, and were used for 8-21 d of age. Then, grower diets with 20.5% CP and 3,250 kcal of ME/kg, and were provided for 22-42 d of age. Compared with the PC group, NC group showed impaired growth performance (BW gain, FI, and FCR), and bone quality (dry weight, breaking strength and contents of ash and P in tibia). However, in most cases, these impairments were ameliorated dose-dependently by the addition of BU and GBU in diets, and the restoration magnitude was greater in GBU than in BU treatment. Total P excretion decreased in NC group and further decreased dose-dependently with increasing levels of BU and GBU. Except for the values in PC group, total P retention increased as the total P excretion decreased. In conclusion, dietary BU and GBU restored the growth performance and bone quality impaired by the P deficiency, and improved P retention in broilers, which suggested that buckwheat, especially when germinated, can be used as an alternative phytase source in broiler diets. [ABSTRACT FROM AUTHOR]

Numerous studies have been conducted worldwide and more specifically in Brazil assessing the consequences of biochar amendments on the soil properties and on the agronomical production. The present study aimed to evaluate the effects of biochar of coffee residues on the physicochemical characteristics of an Entisol and water use efficiency of maize ( Zea mays ). Two types of biochar were produced with both coffee ground (CG) and coffee husk (CH) and their physicochemical properties were characterized. A greenhouse pot experiment, quantifying the growth of maize, with different rates of biochar amendments and fertilizing procedures was conducted in a completely randomized design. Treatments consisted in four replications of (i) control (native soil), (ii) synthetic fertilization and (iii) organic fertilization with cow manure, and (iv) the two types of biochar in four doses (4, 8, 12 and 16 Mg ha − 1 ). Specific surface area (SSA) of CH was significantly higher than CG biochar but both types of biochar had higher SSA than soil. Nutrient and water retention properties of soil and maize growth were significantly improved with increasing biochar doses. The water use efficiency was 50% higher for the treatment with the highest dose of biochar. This is a significant found considering the potential of growing maize on a sandy soil in a dry regions of Brazil. Nutrient use efficiency as well as the C content in Entisol were largely improved by the use of biochar. Determination of SSA was a quick and robust method to anticipate the benefits of biochar on water retention of soil. [ABSTRACT FROM AUTHOR]

Purpose: Phosphorus retention (TPacc) is one of the major water quality regulators in lakes. The current study aimed at ascertaining the specific lake characteristics regulating TPacc. Moreover, we were interested whether NAO (North Atlantic Oscillation), a proxy of climatic forcing, can explain variability in TPacc, additionally to that ascribed to lake characteristics.Materials and methods: Sediment cores were obtained from 21 Finnish lakes, subject to radiometric dating and measurements of TP concentrations. Principal components (PCs) were generated using lake characteristics that are usually included into the modelling of TPacc (e.g. lake area, lake depth, catchment area, P inflow) but also the parameters that the classical models usually missed (e.g. anoxic factor). We used significant principal components (PCs), specific combinations of lake characteristics and monthly NAO values as predictors of TPacc.Results and discussion: Lake characteristics explained the bulk of TPacc variability. The most influential factors (positive drivers) behind TPacc included PC1 (representing mainly deep lakes), PC2 (small lakes with high levels of anoxia and water column stability), PC3 (productive lakes with large catchment area and short water residence time), PC4 (lakes with high water column stability, low anoxic factor and relatively high sediment focusing) and PC5 (lakes with high levels of P inflow, anoxia and long water residence time). Additionally, we found a potential negative effect of NAO in October on the annual TPacc. This NAO was significantly positively related to temperatures in surface and near-bottom water layer (also their difference) in autumn, suggesting the possible implications for the internal P dynamics. Increased mineralization of organic matter is the most likely explanation for the reduced TPacc associated with NAO-driven water temperature increase.Conclusions: The analysis presented here contributes to the knowledge of the factors controlling P retention. Moreover, this spatially and temporally comprehensive sediment data can potentially be a valuable source for modelling climate change implications. [ABSTRACT FROM AUTHOR]

The main horse phosphorus excretion pathway is through the dung. Phosphorus originating from animal dung and manure has harmful environmental effects on waters. The number of horses has increased in many countries, and several studies have pointed that leaching of P from horse paddocks and pastures are hotspots for high P leaching losses. The hypothesis was that feeding regimes might influence phosphorus digestibility and excretion in feces, and therefore the environmental impact of horse husbandry. A digestibility experiment was conducted with six horses fed six forage-based diets to study phosphorus utilization and excretion in feces. The study method was a total collection of feces. The experimental design was arranged as an unbalanced 6 × 4 Latin Squares. Phosphorus intake increased with an increasing concentrate intake. All studied diets resulted in a positive P balance and, the P retention differed from zero in all except the only-hay diet, in which the intake was lower compared to the other diets. The digestibility of P varied from 2.7 to 11.1%, and supplementing forage-diets with concentrates slightly improved P digestibility (p = 0.024), as it also improved the digestibilities of crude protein (p = 0.002) and organic matter (p = 0.077). The horses excreted an average of 20.9 ± 1.4 g/d P in feces. Excretion was smallest (20.0 g) in horses on a hay-only diet (p = 0.021). The average daily phosphorus excretion resulted in 7.6 kg P per year. The soluble P part of the total P in feces accounted for about 88% of the P excreted in feces, and is vulnerable to runoff losses and may leach into waters. Thus, horse dung may pose a potential risk of P leaching into the environment if not properly managed, and is not less harmful to the environment than that from other farm animals. Supplementation with inorganic P should be controlled in the diets of mature horses in light work to decrease the excretion of P in feces.

A feeding trial was conducted for 60 days to study the effects of the combination of microbial phytase and citric acidon phosphorus utilization in Cyprinus carpio fingerlings. Four diets designated as diet without phytase or inorganic phosphorussupplementation (T1), with 1.1% MSP (T2), with 0.55% MSP and phytase (T3) and with 0.55% MSP, phytase andcitric acid (T4). Four replicate groups of 20 fish were fed two times daily until satiation. Phosphorus digestibility and retentionwere measured as well as the fish growth performance. It is concluded from the results that the addition of microbial phytaseand citric acid enhances the availability of phosphorus from plant sources, improves bone mineralization, growth and feedefficiency. Combining a low dose of citric acid to the phytase significantly increased the positive effects of the enzyme.

The effect of phytase supplementation to a low fish meal based diet on growth performance and phosphorus utilisation was investigated in sex-reversed red tilapia. Diets were prepared without phytase or inorganic phosphorus supplementation, with phytase, with supplemented inorganic phosphorus and with both phytase and supplemental inorganic phosphorus. Available phosphorus was set below requirement and the total phosphorus set to meet requirement for tilapia. After 8 weeks, there were significant differences in weight gain and protein utilisation between diets. There was an effect of phytase addition and inorganic phosphorus supplementation on bone phosphorus and whole-body phosphorus (p