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Wijesundara, Sunetra M. "Relationships of soil test phosphorus with soil properties and phosphorus forms." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151136/.
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roberts, john christopher. "Impact of Manure and Soil Test Phosphorus on Phosphorus Runoff from Soils Subjected to Simulated Rainfall." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-06162005-123000/.
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Runoff from agricultural fields amended with animal manure or fertilizer is a source of phosphorus (P) pollution to surface waters, which can have harmful effects such as eutrophication. The objectives of this study were to evaluate the impact of soil P status and the P composition of manure sources on P in runoff, characterize the effects of manure sources on mass loss of dissolved reactive P (DRP), total dissolved P (TDP), algal available P (AAP) and total P (TP) in runoff, and enhance the PLAT database with respect to soluble P attenuating factor (SPAF) and non-soluble P attenuating factor (NSPAF) values. Soil boxes set at 5% slopes received 7.5 cm hr-1 of simulated rainfall. Study soils included a Kenansville loamy sand (loamy siliceous subactive thermic Arenic Hapludults, a Coastal Plain soil) and a Davidson silt loam (kaolinitic thermic Rhodic Kandiudults, a Piedmont soil). Soil test P concentrations ranged from 16 to 283 mg P kg-1. Sources of P included broiler litter (BRL), breeder manure (BRD), breeder manure treated with three rates of alum (Al2(SO4)3) BRD0-0 kg m-2, BRDL-3.9 kg m-2, and BRDH-7.8 kg m-2 and DAP along with an unamended control. All manure sources were applied at 66 kg P ha-1. Water extractable P (WEP) represented an average of 10 ?b 6% total P in manure. Runoff samples were taken over a 30-min period. Piedmont soil contained greater amounts of clay, Al and Fe concentrations, and higher P sorption capacities that produced significantly lower DRP, TDP, AAP, and TP losses than the Coastal Plain soil. Runoff P loss did not differ for low and high STP soils of same taxonomy with the exception of AAP mass losses for Coastal Plain soil samples. Water extractable P in manures accounted for all DRP lost in runoff with DRP correlating strongly with WEP concentration (0.9961). A weak relationship between DRP in runoff and WEP applied to soil boxes was observed (R2=0.6547) and increased when a possible outlying manure treatment, BRL, was omitted from regression data (0.9927). Overall, manures containing the highest WEP concentrations supplied the largest losses of DRP in runoff. Manure treated with 3.9 and 7.8 kg m-2 of Al2(SO4)3 (alum) decreased DRP in runoff by 29%. Values calculated for PLAT SPAF and NSPAF coefficients were higher for Coastal Plain soil than Piedmont soil and overall higher than default values in PLAT. Management based on these results should help minimize harmful effects of P in runoff.
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Sekhon, Bharpoor Singh. "Modeling of soil phosphorus sorption and control of phosphorus pollution with acid mine drainage floc." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2530.
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Thesis (Ph. D.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains xiv, 210 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Ebuele, Victor Pghogho. "Phosphorus speciation in soil and plants." Thesis, Bangor University, 2016. https://research.bangor.ac.uk/portal/en/theses/phosphorus-speciation-in-soil-and-plants(c9a2b08e-cca7-48ad-ac49-79b772d17602).html.
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To better understand the dynamics of P in soil and plants, chemical characterization and solution 31P nuclear magnetic resonance spectroscopy (NMR) were applied to a natural vegetation system dominated by bracken (Pteridium aquilinum (L.) Kuhn) and British bluebells (Hyacinthoides non-scripta (L.) Chouard ex Rothm.) and to different types of organically amended agricultural soils. Organic P (Po) was dominant in the natural system while the agricultural soil of the total P more than 80% was inorganic P (Pi) mainly in the form of orthophosphate. A detailed quantitative analysis of the P forms in three fields assigned codes (FWa, FWo and FWp) with contrasting coverage of bracken and bluebell, their original native vegetation was undertaken in 2013. Soils were collected in areas dominated by both plants, from April to September 2013 weeks (W1 – W20) in order to cover the main above-ground lifecycle stages. Chemical characterization of the soils showed differences in total P, total Po and plant available P (Mehlich-3 extraction). The total P content of the soils from the three fields showed a slight non-significant increase after bluebell flowering. Quantitative assessment using 31P NMR showed differences in the nature of P forms in the soil and this was reflected in the nature of the vegetation cover, and extent of plant litter deposition. The most dominant P form found in the NaOH-EDTA soil extracts of FWa and FWo were the organic P forms (68.1 – 84.3 %), (61.3 – 79.1 %) respectively, most especially orthophosphate monoesters (53.1 – 83.8 %), (50.3 – 79.4 %), mainly as myo-inositol hexakisphosphate (myo-IP6) or phytate, while the inorganic P form (32.8 – 58 %) was the most dominant on FWp mainly as orthophosphate (ortho-P) (30.7- 56.8 %). The increased myo-IP6 concentration in the soil was linked to the shedded old bluebell bulb below ground containing up to 40 % myo-IP6. Bluebell seeds, another potential route of P transfer into soil, also contained 60 % myo-IP6 of total P. 31P nuclear magnetic resonance (NMR) spectroscopy was also used in elucidating the speciation and distribution of P species in diverse plant seeds (cumin, fennel, flax, mustard, poppy and sesame seeds). Phosphorus speciation by 31P NMR showed that P was mainly present in organic forms such as phytate and α- and β-glycerophosphate in poppy, sesame, mustard, fennel and cumin seeds. The inorganic P forms detected included orthophosphate and pyrophosphate. In particular, the highest amount of orthophosphate was found in NaOH-EDTA extracts of fennel seeds (41.7 %) and the lowest in mustard seeds (9.3 %) and sesame seeds (6.9 %). For the organic P forms, the highest concentration of phytate was found in mustard xiv seeds (85.2 %) and the lowest in fennel seeds (43.3 %). This result implied that in most seed producing plants P, transferred from the plants vegetative parts to the developing seeds during seed maturation, is converted to phytate (organic P) in addition to being stored as orthophosphate (inorganic P). Phenologically either bracken or bluebells grow actively throughout the year. In a semi-natural ecosystem, competition between bluebell and bracken is highest on bracken crozier emergence, which dense bluebell coverage seem to delay. P speciation was identified as an underpinning driver: For bracken, P was present mainly in form of soluble inorganic orthophosphate (41- 96.1 %), while glycerophosphates were the main Po (2.4 – 58.9 %) detected in rhizome, pinnae or stipe. Contrarily bluebell bulbs contained mostly myo-IP6 (6.7 – 52.3 %) possibly aiding survival at low temperatures, because of bluebell’s active growth starting in early autumn. Within the whole plant, the bulb acts as a source and primary sink of P, mainly as myo-IP6. This might be a survival mechanism against P supply interruption during bluebell’s growth cycle while at the same time making P less available for others. The relatively higher total P content of bluebell bulbs (0.67 – 2.7 g kg-1) compared to bracken rhizomes (0.43 – 1.30 g kg-1) also supports this. Bracken’s competitive advantage relies on its dominance of the extensive rhizome system, for which this study showed its ability to redistribute nutrients. Specifically, there was very little differences in the P species between plant parts; instead orthophosphate was shuttled from rhizome to pinnae and returned. The effect of a variety of organic fertilizers additions (pig or cow slurry, farm yard manures, broiler litter, compost and paper sludge/waste) from 1990 to 2014 on the distribution and accumulation of soil Pi and Po forms in three different soil types Harper Adams (HAU, sandy loam), Terrington (TER, silty clay loam) and Gleadthorpe (GT, loamy sand) was investigated. A sequential fractionation scheme and 31P NMR of NaOH-EDTA soil extracts was used to speciate P. Total P concentration in all soils ranged from 0.76 g kg-1 – 1.49 g kg-1 and was predominantly inorganic P (51.2 – 90.8 %). The differences in pH suggests that P species in HAU and GT (pH 6.5) would likely be bound to Al/Fe oxides and hydroxides. At more alkaline pH for TER (pH 7.9) mainly Ca-P minerals would occur. Phosphorus speciation analysis supported this with orthophosphate (82.9 –95.5 %) as the most dominant P form detected. This high inorganic to organic P ratio in conjunction with a low C/P ratio (< 200) suggested that mineralization of organic P mainly occurred in these soils. Myo-IP6 was the most dominant organic P form (1.6 – 8.9 %) followed by scyllo-IP6 (0.7– 4.6 %). Orthophosphate diesters were detected in only one sample (GT) but in trace amounts (0 – 0.5 %). Polyphosphate and xv phosphonates were not detected in any sample. The similar composition of P species across the various treatments suggests that the additions of different manures to the soil only lead to an increase in inorganic P species mainly ortho-P, likely caused by the rapid mineralization of organic P forms in the manure-treated soils. The result also suggested that the abundance and accumulation (Legacy P) of the various P forms, as determined by sequential extraction, were dependent on the nature of manure treatment, soil type and pH of the soils.
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Pierzynski, Joy. "THE EFFECTS OF P FERTILIZER ADDITION ON P TRANSFORMATIONS ON HIGH-P FIXING AND GRASSLAND SOILS." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/34548.
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Doctor of PhilosophyDepartment of Agronomy
Ganga M. Hettiarachchi
Although phosphorus (P) is an essential nutrient for the growth of plants, it is one of the most limiting nutrients in terms of availability as a high proportion of applied P rapidly transforms into insoluble forms with low solubility in soils. To further understand the fate of P applied to soils, two separate but related studies using three high P-fixing soil types each were used for which the objectives were to investigate the mobility, availability, and reaction products from two granular and one liquid P fertilizer alone or plus a fertilizer enhancement product. Energy dispersive spectroscopy showed a substantial amount of P remained in the granule following a 5-week incubation. At the end of the 35-day incubation period there was evidence that the fluid fertilizer was superior over the granular sources in terms of enhanced diffusion and extractability of P for three calcareous soils with varying levels of CaCO3. Phosphorus x-ray absorption near-edge structure (XANES) spectroscopy results in conjunction with resin-extractable P indicated a strong negative correlation between Ca-P solids formed and P extractability, suggesting that degree of Ca-P formation limits P solubility. For the three acidic P-fixing soils the results were complex. In two out of three acid soils, liquid P treatments diffused farther from the application point than the granular treatments. Phosphorus XANES results suggested that Fe-P or Al-P interactions control the overall P solubility. Integration of pH, resin extractable-P and XANES results suggested the P retention mechanism was either dominated by adsorption or precipitation depending on soil pH. More acidic soil conditions favored precipitation. The objectives of the third study were to observe how long-term (14 years) addition of P with or without N influences the inorganic and organic P pools in a native grassland soil using sequential fractionation, XANES, and 31P-nuclear magnetic resonance (NMR) spectroscopy. The overall results suggested that P and N fertilization and associated changes in plant productivity induced significant changes in soil P pools such as Ca-P, phytic acid, monoesters, and residual forms of P. The addition of P alone induced formation of inorganic P forms while the addition of P and N induced transformation of residual P forms into more labile and/or organic P forms.
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Abou, Nahra Joumana. "Modeling phosphorus transport in soil and water." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102946.
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The main objective of this project was to investigate and model phosphorus (P) transport in soil column studies. A model named HYDRUS-NICA was developed, by coupling a hydrological and transport model (HYDRUS-1D model) with an aqueous chemical model (non-ideal competitive adsorption - NICA), to improve the predictions of P transport in soil and water. The HYDRUS-NICA model was developed by replacing the non-linear empirical (Freundlich and Langmuir) equations of the HYDRUS-1D model with the NICA model equations. The numerical accuracy of the HYDRUS-NICA model was then evaluated by comparing the relative errors produced by the HYDRUS-NICA and HYDRUS-1D models. The results showed that the numerical schemes of the HYDRUS-NICA code are stable.The ability of the NICA model to describe phosphate (PO4) adsorption to soil particles was tested using soils collected from agricultural fields in southern Quebec. The surface charge and PO4 adsorption capacity of these soils were measured. Results were used to estimate the NICA model parameters using a non-linear fitting function. The NICA model accurately described the surface charge of these soils and the PO4 adsorption processes.
The HYDRUS-1D model was applied to simulate water flow and PO4 transport in re-constructed soil column experiments. The HYDRUS-1D model was calibrated based on physical and chemical parameters that were estimated from different experiments. Overall, the HYDRUS-1D model successfully simulated the water flow in the columns; however, it overestimated the final adsorbed PO4 concentrations in the soil. The discrepancies in the results suggested that the HYDRUS-1D model could not account for the differences in the soil structure found in the columns, or that the Freundlich isotherm could not adequately describe PO4 adsorption.
The HYDRUS-NICA model was calibrated and validated with results from re-packed column experiments. The simulated results were then compared with results obtained by the HYDRUS-1D model. The overall goodness-of-fit for the HYDRUS-1D model simulations was classified as poor. The HYDRUS-NICA model improved significantly the prediction of PO4 transport, with the coefficient of modeling efficiency values being close to unity, and the coefficient of residual mass values being close to zero. The HYDRUS-NICA model can be used as a tool to improve the prediction of PO4 transport at the field scale.
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A, Heskett Richard. "Determining soil phosphorus concentrations using cattail indicators." Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1048396.
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Excess phosphorus is often identified as a major factor in the eutrophication of wetlands and lakes. Often attributed to agricultural practices, the specific source of a large part of this excess has been difficult to determine. The term "nonpoint" source is often used to broadly describe the inflow along waterways of significant amounts of this essential plant nutrient and other pollution. This research was intended to determine the effectiveness of using cattails (Typha), a common plant along waterways, as indicators of plant available phosphorus in the soil along these waterways. Two sites in the southern part of Michigan's lower peninsula (45°N,84°W) where cattails grew were systematically examined for phosphorus and certain cattail characteristics. Plant and soil data were gathered in a grid-like pattern to determine both the relationship of paired data and their spatial distribution across each site. One set of data was shown to be significant. At one site, the density of cattails is weakly correlated with Phosphorus concentrations. Of particular importance, the spatial distribution of both variables is also noticeably similar at the site. No significant correlation between other data was shown. There is also no apparent similarity in spatial distribution. Though weakly correlated, we were able to support a hypothesis that a reasonable correlation exists between cattail density and plant available phosphorus at one site. The spatial distribution of these traits are also similar suggesting that cattails may, in some cases, be useful as indicators of excess phosphorus, perhaps better defining its source than “nonprint”.Department of Biology
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Undercoffer, Jason. "Monitoring Phosphorus Transport and Soil Test Phosphorus From Two Distinct Drinking Water Treatment Residual Application Methods." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243532451.
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Norton, E. R., J. C. Silvertooth, and L. J. Clark. "Phosphorus Fertility Evaluation in Graham County." College of Agriculture, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/197714.
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A series of three phosphorus (P) fertility experiments were conducted in 2001 in Graham County. These studies follow similar experiments conducted over the past three seasons. Results from 2001 were consistent with previous results indicating a positive relationship between yield and P fertilizer applications in relation to soil test indices. Modest yield increases were observed from a minimum of 25 to 80 lbs. lint per acre with an application of approximately 70 lbs. of P as P₂O₅ per acre. Yield differences from previous years have been as great as 170 lbs. of lint per acre. With the increased use of UAN-32 as a primary fertilizer source and a reduction in the application of P fertilizers, which is typically associated with a rotation of small grains, a depletion of soil P is a potential result. A continuation of this research with varying rates of P fertilizer will take place in 2002 in an attempt to relate soil test P levels to yield increases observed in recent years. The results of this research demonstrate the possible need for a return to use of fertilizers with supplemental P for optimum yields that would be predictable based on soil test results.
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Norton, E. R., and L. J. Clark. "Phosphorus Fertility Evaluation in Graham County." College of Agriculture, University of Arizona (Tucson, AZ), 2003. http://hdl.handle.net/10150/197930.
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A field study was implemented in 2002 in the Upper Gila River Valley of Safford to investigate the effects of varying phosphorus (P) fertilization rates on yield and quality of Upland cotton. This study is a continuation of work performed in this valley that began in 1998. This study was organized in a randomized complete block design with four treatments including four rates of 10-34-0 fertilizer, 0, 15, 30, and 45 gallons per acre (gpa) replicated 4 times. Lint yield results indicate a positive response to the application of 10-34-0 fertilizer with yield increasing linearly up to 30 gpa. The 45 gpa treatment resulted in a slightly lower yield than the 30 gpa treatment. This was likely due to the high level of nitrogen (N) fertilizer and excessive vegetative growth at the expense of reproductive growth (yield) that occurred in treatment 4.
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Lee, Seung Hwan. "Phosphorus removal mechanisms in soil and slag media." University of Technology, Sydney. Faculty of Engineering, 1995. http://hdl.handle.net/2100/356.
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Excessive phosphorus (P) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by soil and slag is an attractive solution if the P sorption capacity of soil or slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed experiments were conducted to study P removal under static and dynamic conditions, and mathematical models were developed to describe these processes. The kinetic studies on P sorption onto a sandy loam soil from North Sydney, Australia, and dust and cake waste products from the BHP steel industry revealed that P sorption is a slow process. More than 90% of the P was adsorbed within 70, 12 and 60 hours in a mixing system for soil, dust and cake respectively while it was within 240, 24 and 120 hours respectively in a static (no stirring) system. Dust adsorbed P the most, compared to the other adsorbents (220-225 times and 4-5 times of the sorptivity of soil and cake respectively). P sorption in the batch experiments was described better by an equation using the Langmuir isotherm than one using the Freundlich isotherm. The kinetics of P sorption were satisfactorily explained by a static, physical, non-equilibrium sorption model (SPNSM). The pH of the P solution played a critical role in the extent of removal and the removal mechanisms of P. Removal was at a minimum at pH 2. The effect of pH on P removal varied depending on the type of adsorbents and the initial P concentration. The dominant removal mechanism of P at pH<8 was physical sorption, while it was chemical precipitation at pH>10. Batch flocculation experiments revealed that the P removal efficiency increased with an increase of adsorbent dose, flocculation (contact) time and mixing rate. P sorption is affected by the presence of NH4 which competes for available sites on the adsorbents. The amount of P adsorbed by dust and cake in the presence of NH4 was less than that in a single solute system. The reduction percentage of P for dust ranged from 33 to 57%. Detailed column experiments conducted with soil, dust and cake as media indicated that dust and cake have much higher sorption capacities than soil. The solid phase P concentrations on dust and cake calculated from batch experimental isotherm constants are substantially higher than those estimated.
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McLaughlin, Michael John. "Phosphorus cycling in soil under wheat-pasture rotations /." Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phm1615.pdf.
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Fischer, Peter. "The degree of phosphorus saturation of agricultural soils in Brazil and Germany: New approaches for risk assessment of diffuse phosphorus losses and soil phosphorus management." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19589.
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Diffuse Phosphor (P)-Austräge aus der Landwirtschaft tragen zur Gewässereutrophierung bei. Der Phosphorsättigungsgrad (DPS) ist ein etablierter Parameter, um das P-Austragsrisiko aus Böden zu erfassen. Ein bodentypunabhängiger Ansatz, der die Abschätzung des DPS durch eine einfache Standardmethode wasserlöslichen P (WSP) ermöglicht (WSP-DPS-Ansatz), wurde an europäischen Böden entwickelt. In der Dissertation wurde dieser Ansatz erstmalig: i) an tropischen Böden getestet und ii) dazu verwendet P-Austragsrisiken von Boden-P-Monitoringdaten und von landwirtschaftlichen Institutionen empfohlenen P-Gehalten abzuleiten. Neben dem DPS wurde der Einfluss der in Brasilien gängigen anorganischen Oberflächendüngung auf das Austragsrisiko mittels Laboranalysen und Feldstudien erfasst. Die Bodentypunabhängigkeit des WSP-DPS-Ansatzes wurde für Böden Brasiliens bestätigt. Infrarotspektroskopische Analysen lieferten eine Erklärung für relativ niedrige gelöste P-Konzentrationen im Oberflächenabfluss von Oxisols. Pedotransferfunktionen zwischen WSP und Methoden, die in Brasilien und Deutschland zur Abschätzung pflanzenverfügbaren P verwendet werden, ermöglichten die Berechnung von DPS-Werten aus Monitoringdaten. Erste DPS-Karten zeigten relative geringe Austragsrisiken für das Untersuchungsgebiet in Brasilien und hohe Risiken für Deutschland, die teilweise durch unterschiedliche empfohlene Boden-P-Gehalte erklärbar waren. Um mit einer einfachen und kosteneffizienten Methode sowohl die landwirtschaftliche Produktion als auch den Gewässerschutz zu berücksichtigen, wurden die Wasser- und CaCl2-Methode zur Abschätzung von pflanzenverfügbarem P mit dem WSP-DPS-Ansatz kombiniert. Dieser Ansatz könnte helfen die Herausforderungen zu lösen mit denen die Menschheit in den nächsten Jahrzehnten bezüglich P in der Landwirtschaft konfrontiert sein wird: Einer effizienten Nutzung der limitierten Ressource P und dem Schutz der Gewässer vor diffusen P-Einträgen.Diffuse phosphorus (P) losses from agriculture contribute to the eutrophication of surface waters. The degree of P saturation (DPS) is an established parameter for assessing the risk of P loss from agricultural soils. A soil type-independent approach for estimating the DPS by a simple standard method of water-soluble phosphorus (WSP; the WSP-DPS approach) was developed on European soils. In the thesis, the WSP-DPS approach was for the first time: i) tested on tropical soils and ii) used to derive P loss risks from soil P monitoring data and from recommended soil P levels by agricultural institutions. In addition to DPS, laboratory analyses and field studies were combined to assess the risk of P loss associated with the superficial application of inorganic fertilizer, which is commonly used in Brazil. The soil type-independency of the WSP-DPS approach was confirmed for soils of Brazil. Infrared spectroscopic analyses provided an explanation for the relatively low dissolved P concentrations in the surface runoff of Oxisols. Pedotransfer functions were determined between WSP and methods used to estimate plant-available P in Brazil and Germany and allowed for the transformation of soil P monitoring data into DPS values. The first DPS maps revealed relatively low P loss risks for the investigation area in Brazil and high risks for Germany. This difference was partly explainable by the recommended soil P levels in the two countries. To consider both agricultural production and the protection of surface waters in soil P management with a simple and cost-effective method, the soil test methods of using water and CaCl2 to estimate plant-available P and the WSP-DPS approach were combined. This approach could help to solve the challenges humanity faces regarding P in agriculture in the coming decades: An efficient use of the limited resource P and the protection of surface waters from diffuse P losses.
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Mukherjee, Atanu. "Evaluation of soil test methods as indicators of releasable phosphorus in wetland soils." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011845.
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Florence, Robert J. "Comparing soil testing methods for soil organic matter, lime requirements, and developing a phosphorus soil test correlation." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/18903.
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Doctor of PhilosophyDepartment of Agronomy
Dave Mengel
The Kansas State University Soil Testing Laboratory currently uses the Walkley-Black (WB) method for soil organic matter (SOM) estimations, the Shoemaker-Mclean-Pratt (SMP) buffer for lime recommendations, and bases the soybean phosphorus (P) critical value for P fertilizer recommendations off other crops. Hazardous waste is produced from WB and SMP creating a health hazard for workers, and substantial cost for handling and disposal. The substantial increase in land area devoted to soybean creates the need to validate currently assumed soil test P critical value and check the current P recommendations for that crop. Overarching objectives of this dissertation are to find suitable non-hazardous replacements for WB and SMP, and to find the soybean P critical value in Kansas. Three common methods used to estimate SOM are WB, dry combustion (DC), and loss on ignition (LOI). An experiment was set up using 98 Kansas soils to compare WB, scooped and weighed, LOI scooped, and DC weighed. All methods correlated well to each other with LOI to weighed WB, LOI to DC, and WB weighed to DC, having correlation coefficients of 0.97, 0.98, and 0.98, respectively. The lowest variability was observed with DC, followed by WB weighed, LOI, and then WB scooped with average standard deviations of 0.04, 0.13, 0.17, and 0.24, respectively. Two non-hazardous alternatives to the SMP buffer to determine soil lime requirement are the Sikora buffer, and the modified-Mehlich buffer. Sikora’s buffer is designed to mimic SMP. Buffer values alone or Mehlich’s equation may be used to calculate lime requirements. Thirty seven soils with a pH less than 5.8 were incubated at lime rates 0, 2240, 4480, 8960, and 17920 kg ECC ha[superscript]-1. Amount of lime required to reach pHs 6.0, 6.3, and 6.6 was calculated. Mehlich’s equation better predicted lime requirements for all target pHs and buffers than buffer pH alone. The Sikora buffer with Mehlich’s equation provided a better lime estimation than the Mehlich buffer using Mehlich’s equation. A P correlation and calibration study was conducted with soybeans at 23 sites in Eastern Kansas from 2011 to 2014. Soil Mehlich-3 P available P was compared to relative soybean yield at these sites. Soybean P critical value was found to be between 10 and 15 or 11.6 mg kg[superscript]-1 using Cate-Nelson, and linear-plateau models, respectively. A linear response to P and relative yield was observed on soils testing between 3 and 8 mg kg[superscript]-1, but not on higher testing soils.
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Croat, Samantha Jo. "Phosphorus Dynamics and Crop Productivity in Bakken Crude-Oil Remediated Soils." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/29169.
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Thermal desorption (TD), a remediation method used to remove hydrocarbons from contaminated soils, may cause changes in soil properties that threaten soil function and plant productivity. The goal of this research is to better understand the effect that TD treatment has on soils intended for agricultural use. A series of soil phosphorus (P) sorption and desorption experiments were conducted on soils before and after TD treatment to determine P availability for plant uptake and risk for run-off. TD-treated soils retained more P, likely due to mineral transformations of Fe- and Al-oxides. In addition, a three-year field study using mixtures of topsoil (A), crude-contaminated soil (SP), and TD-treated soils (TDU) was conducted. Yields were significantly greater in plots that included A in the mixture compared to SP and TDU soils alone. TD-treated soils can be a replacement for topsoil, but the addition of topsoil will reduce the time to successful reclamation.
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Herman, Melissa C. "Laboratory Evaluation and Soil Test Phosphorus Trends in Ohio." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308336863.
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Cooperband, Leslie Rose. "Soil phosphorus dynamics in a humid tropical silvopastoral system /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487777901660164.
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Misra, Rabindra Kumar. "Root growth and phosphorus uptake in relation to soil structure and strength /." Title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phm6781.pdf.
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Fischer, Peter [Verfasser]. "The degree of phosphorus saturation of agricultural soils in Brazil and Germany: New approaches for risk assessment of diffuse phosphorus losses and soil phosphorus management / Peter Fischer." Berlin : Humboldt-Universität zu Berlin, 2018. http://d-nb.info/1185174141/34.
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Whitehead, Peter. "Phosphorus retention from dairy slurry in four grassland soils and release to soil solution." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250638.
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Shetterly, Benjamin James. "Soil Phosphorus Characterization and Vulnerability to Release in Urban Stormwater Bioretention Facilities." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4354.
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Modern urban stormwater infrastructure includes vegetated bioretention facilities (BRFs) that are designed to detain water and pollutants. Phosphorus (P) is a pollutant in stormwater which can be retained in BRF soils in mineral, plant, and microbial pools. We explored soil properties and phosphorus forms in the soils of 16 operational BRFs in Portland, OR. Since soil hydrology can significantly impact P retention, we selected BRFs along an infiltration rate (IR) gradient. We conducted sequential fractionation and tests of P pools and measured P release in a subset of soils after drying and flooding samples for ten days. We hypothesized that mineral or organic soil P forms would be correlated with IR, and that vulnerability to P release would depend on the interaction of drying and flooding treatments with P forms and pools. IR did not significantly explain differences in P forms. Soil TP was elevated across all sites, compared with TP in agriculturally-impacted wetlands and was substantially composed of soil organic matter (OM)-associated P. Phosphorus sorbed to mineral Fe and Al oxides- was variable but positively correlated with water-extractable P. The concentration gradient of water-extractable P was primarily controlled by overall P pools. Experimentally induced P releases were seen in 5 of 6 soils exposed to drying conditions, presumably released through microbial mineralization of OM. Only one site showed significant P release following the flooding treatment. Our measurements supported the idea that Fe and Al oxides provide P sorption capacity in these BRF soils. Variable inputs of P to BRFs through stormwater and litterfall may contribute to variability in P profiles and P release vulnerability across sites. Design specifications and management decisions relating to bioretention soils (e.g. establishment of acceptable soil test P levels, focusing on P forms known to influence vulnerability of P release) may benefit from detailed biogeochemical investigations.
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Coyle, Kieran. "An investigation of the role of soil micro-organisms in phosphorus mobilisation : a report submitted to fulfil the requrements of the degree of Doctor of Philosophy." Title page, table of contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phc8814.pdf.
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Yokoyama, Daiki. "Significance of soil organic phosphorus for the maintenance of tropical rain forest ecosystems." Kyoto University, 2019. http://hdl.handle.net/2433/236631.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第21470号
農博第2313号
新制||農||1064(附属図書館)
学位論文||H31||N5165(農学部図書室)
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 北山 兼弘, 教授 本田 与一, 教授 舟川 晋也
学位規則第4条第1項該当
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Ramwell, Carmel Teresa. "Nitrogen and phosphorus dynamics in upland peat." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245573.
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Landry, Christine. "Phosphorus fertilization and mycorrhizae influence soil phosphorus dynamics, corn nutrition and yield under reduced-tillage practices." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115705.
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Grain corn (Zea mays L.) production occupies more farmland than any other annual crop in Quebec and is expanding demand from the livestock sector and the emerging bioethanol industry. Corn production requires high nutrient inputs and intensive tillage (IT). Many producers have thus switched to conservation tillage systems like ridge-tillage (RT) to overcome soil compaction and erosion problems that are common in IT systems. However, fertilizer guidelines developed for IT soils are used in RT although RT adoption greatly modifies phosphorus (P) dynamics. Lower fertilizer P requirements are expected because arbuscular mycorrhizal (AM) symbiosis known to enhance plant P nutrition are minimally disrupted under RT, compared to IT systems. A two-year study was conducted on a commercial farm in the Monteregie region (Quebec, Canada) to investigate the effects of P fertilizer rates and soil P-saturation status on corn early growth, nutrition and yield. Surface soil plant-available P was monitored in situ with anionic exchange membranes (P AEM) from seeding to the end of July. The effects of indigenous AM fungi on corn parameters and rhizosphere soil P pools were also investigated in untreated (AMNI) or AM-inhibited fungicide-treated (AMI) soils. Quebec's P fertilizer guidelines underestimated the soil P fertility in studied soils. Adding inorganic P (Pi) did not improve the early corn P nutrition, growth or yield, and had little impact soil PAEM. Variations in PAEM were better explained by climatic variables. AMNI corn had similar early development and high yield, regardless of whether P fertilizer was applied, whereas AMI plants needed P fertilizer to produce optimal yield. AMNI corn had reduced dependence on Pi inputs due to more efficient uptake of soil solution P i in surface and rhizosphere soils during the first 22 days after seeding (DAS), In the rhizosphere, available-Pi pool appeared to be used first to replenish the resin-P pool, but over the longer term, AM symbiosis also enhanced NaHCO3-Po mobilization through a mechanism that remains unclear. Deeper understanding of the mechanisms by which AM fungi alter soil P dynamics will contribute to the development of more sustainable P fertilizer programs for RT systems.
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Silvertooth, J. C., E. R. Norton, and A. Galadima. "Evaluation of Potassium and Phosphorus Fertility in Arizona Soils." College of Agriculture, University of Arizona (Tucson, AZ), 2001. http://hdl.handle.net/10150/211298.
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Two field experiments were conducted during the 2000 growing season to address fertility recommendations for fertilizer phosphorus (P) and potassium (K). A K fertility study was conducted near Tonopah, AZ consisting of two treatments, an untreated control and a treatment receiving a total of 20 gallons of K-Sul/acre. No significant differences were observed in leaf blade K concentrations between treatments. Plant growth and development estimates revealed that fruit retention (FR) levels remained consistently higher in the untreated control versus the treated plots. A second study involved treatments consisting of both P and K fertilizers was conducted near Cibola, AZ. Four treatments in this experiment included an untreated control plus treatments of 11-52-0, 0-0-60, and 4-17-40 at 100, 200, and 300 lbs. fertilizer/acre respectively. Plant growth and development estimates were similar among treatments during the season. At the end of the season the untreated control had a slightly higher FR level than the other treatments, which also produced a significantly higher yield. No other differences in yield among the fertilized treatments were observed.
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Alogaidi, Faez Fayad Mohammed. "Understanding rice and soil phosphorus interactions with an emphasis on rice genetics and soil microbes." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=203870.
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Rice is the staple food for nearly one half of the ever growing world's population. Phosphorus (P) deficiency commonly constrains crop productivity on a large area of arable land worldwide. P fertilizer is a finite resource and an expensive input, so it must be used efficiently. The main objective of this study was to investigate plant and soil P interaction in P deficient conditions and understand plant mechanisms that could enhance P uptake efficiency throughout two main research approaches: Firstly, investigating plant and soil microbes' interaction that promotes plant growth in Plimited conditions. Secondly, evaluating the P uptake efficiency of a number of rice genotypes in a high throughput screening systems in order to understand genotypic variations in P uptake mechanisms. The genotypes used were genotyped for the allelic variation in the Pup1 locus and the effect of this QTL on the plant growth was also investigated. In an experiment investigating the influence of soil microbes on rice growth in P deficient conditions, an experimental system where pots were filled with a mix of 95% low P Insch subsoil and 5% Insch topsoil, where the subsoil was sterilized by autoclaving and the top soil was either sterilized or live. Non-autoclaved (live) topsoil caused a significant increase in shoot dry weight (SDW) for IAC 25 compared to autoclaved soil while the opposite was true for Azucena suggesting that the presence of soil microbes is needed for IAC 25 to access soil-bound P under P-limiting condition while for Azucena it is not. Most importantly, a very strong cultivar x treatment interactions on almost all growth parameters and elements in the shoot except for Mn were found. In a dose experiment investigating whether there is a general toxic effect for autoclaving Insch topsoil being used in this study on the growth of IAC 25, a strong positive correlations of plant growth parameters with the percentage of sterile topsoil vi levels were observed indicating that the autoclaved topsoil was not toxic. The influence of soil wash (distilled water added to the soil then extracted) and different types of soil as sources of inocula on the plant growth of rice cultivars were also studied. Soil wash inoculation did not affected plant growth but soil inocula increased the biomass of all rice cultivars (Azucena, IAC 25 and Lemont) tested suggesting that if it is microbes that are important they must be remaining in the soil and are not transferable by washing. Two autoclaved soils did not behave similarly in terms of affecting plant growth of rice cultivars (Azucena and IAC 25). Moreover, the live treatment of a new soil stimulated the growth of both cultivars and the cultivar x treatment interaction that was found in earlier experiment was lost with the use of this new soil. The implication is that the cultivar by autoclave treatment interaction is soil specific. The fluctuating results between the experiments indicate that it is unlikely that such studies can be extended into plant genetics. So, the second approach of the study focused on examining simpler plant/soil P interaction in P limiting conditions. A 25/75% subsoil/sand mix was determined as a P deficient and used to screen 30 rice genotypes in two experiments: the first when watered with Yoshida's nutrient solution (YNS) either with (YNS+P) or without P (YNS-P) to assess whether rice genotypes differ in extracting P added in liquid form while the second was designed to test if shallow and deep-rooted genotypes differ in extracting P present in soil by using rock phosphate in three treatments: when rock P was absent or embedded either in a shallow 10 cm layer or distributed homogenously in soil mix. For both experiments, P treatment x genotype interaction was significant on SDW. On average, YNS-P treatment significantly reduced the SDW for genotypes compared to that of plants grown in YNS+P treatment while the addition of rock phosphate greatly stimulated plant growth where SDW of plants grown in homogenous P and shallow P significantly outgrew vii those in zero P treatment. In both experiments, rice from the aus subgroup grown in -P treatment accumulated significantly more SDW than indica and japonica genotypes. In -P treatment, the genotypes that accumulated higher SDW relative to the others were Black Gora, Rayada, Kasalath, Azucena, IAC 25, Dom Sufid, Aux1Wild type, FR 13A and especially Sadu Cho. In the rock phosphate experiment, both P treatment and genotype affected RDW and root/shoot ratio significantly. Most importantly, two root angle traits (the mean root direction and the weighted average of the unsigned root angles) measured in rhizotrons were correlated with the relative SDW in shallow P (SDW in shallow P/SDW in zero P) slightly stronger than with relative SDW in homogenous P (SDW in homogenous P/SDW in zero P) indicating that the relationship between plant growth and root distribution with depth was altered by the distribution of rock phosphate in soil. In both experiments, the presence of Kasalath alleles in the Pup1 QTL significantly increased SDW of the genotypes. However, some genotypes, especially Dom Sufid and Sadu Cho performed well in these experiments despite lacking the Pup1 allele suggesting that Pup1 QTL is not the only determinant for tolerance to P deficiency. The system appears to be suitable for high throughput screens of rice genotypes.
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Ochwoh, Victor Akangah. "The dynamics of phosphorus extractability, adsorption, and desorption rates as influenced by phosphorus applications and incubation times." Thesis, University of Pretoria, 2002. http://hdl.handle.net/2263/28636.
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In a study to investigate the fate of the applied P in soils, a red-sandy clayey soil (Ferric Luvisols) from Rustenburg (high P fixing) and a red-sandy loam soil (Ferric Acrisols) from Loskop (low P fixing) were used. Sequential P fractionations were used to determine the content of the different P pools to show which pool the applied P was transformed to. The soils treatments consisted of different Prates (0, 25, 50, 100, 150, and 200 mg kg-1), and incubation periods (1, 60, 120, 180, and 240 days) under a laboratory conditions. The sequential P fractionation procedure consisted of extraction with hydrous ferric oxide in a dialysis membrane tube (DMT-HFO), 0.5M NaHC03, O.1M NaOH-P, 1.0M HCI, concentrated HCI, and concentrated H2S04 + H2O2. Approximately 30 to 60 % of the added P were transformed into less labile P pools within one day and 80-90 % after 60 days. This transformation was faster in the Rustenburg than in the Loskop soil showing a higher P fixation capacity. A major part of the P transformation was to the -OH-P1 pool with a recovery of about 30%. In the second experiment an attempt was made to determine P desorption rates by successive DMT-HFO extractions (1, 7, 14, 28, and 56 days) after the transformations of the applied P. This was followed by the sequential extractions to determine the changes and distribution of the added P into different P pools as well as which pools the P was des orbed from. The Rustenburg and Loskop soils were treated to different Prates (0, 25, 50, 100, and 200 mg P kg-1) and incubation periods (1, 120, and 240 days). The cumulative DMT -HFO extraction curves for 56 days showed that desorption could continue for a much longer period. This property is important in the economical management of fertilizer applications rates. Results showed the transformations and distribution of the applied P during incubation periods and proved that all the stable soil P pools contributed to the labile P pool by different proportions after prolonged successive DMT-HFO extractions. Although Rustenburg soil is considered a high P fixing soil, the P release rates under laboratory conditions were high enough to meet the requirements of cotton and tobacco crops. Root systems of these crops do not exploit 100 % soil volume as this laboratory method, which could explain why these crops experience P deficiencies. It is envisage that by using this method the P releasing properties of a soil could be used to develop a P desorption model to determine how much extractable P, with a specific extractant, in a particular soil, should be available at the beginning of a growing season to sustain a high enough P releasing rate to meet the requirements of a certain crop up to the end of the growing season. To do this, a model to describe root development that represents the percentage of the soil exploited P desorption rates that simulate P uptake by plant roots will be necessary.Thesis (DPhil (Plant Production: Horticulture))--University of Pretoria, 2006.
Plant Production and Soil Science
unrestricted
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Deiss, Leonardo. "Soil Organic Phosphorus and carbon on agricultural and natural ecosystems." reponame:Repositório Institucional da UFPR, 2016. http://hdl.handle.net/1884/46044.
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Orientador : Dr. Anibal de Moraes, Dr Jeferson Dieckow e Dr. Alan J. FranzluebbersTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Agronomia. Defesa: Curitiba, 24/10/2016
Inclui referências: f. 47-50;72-77;97-101
Área de concentração: Produção vegetal
Resumo: A disponibilidade de solos e seus recursos está reduzindo com a evolução da humanidade e os impactos negativos, decorrentes do mau uso dos solos, estão afetando o desenvolvimento sustentável da agropecuária mundial. Portanto, se faz necessário o desenvolvimento de alternativas que permitam um uso mais sustentável dos solos, para atender as demandas no setor de produção agropecuária do século 21. O objetivo geral desta tese foi estudar solos de sistemas de produção agropecuária que buscam a intensificação de uso sustentável, ou de ecossistemas naturais, como uma etapa para melhor entender dinâmicas complexas de nutrientes. Foram estudados a composição de fósforo (P) no solo em sistemas integrados de produção agropecuária (SIPA) no subtrópico brasileiro, bem como em ecossistemas naturais em escala global e por fim, a dinâmica do carbono (C) orgânico em um sistema agroflorestal localizado na Carolina do Norte, Estados Unidos da América. O primeiro objetivo específico foi determinar a composição de P no solo de agroecossitemas com baixa e alta complexidade trófica. Especificamente, objetivou-se qualificar e quantificar os componentes orgânicos e inorgânicos de P usando extratos de NaOH-EDTA e espectroscopia de ressonância magnética nuclear, para posteriormente caracterizar a ciclagem de P em resposta ao aumento da complexidade trófica com SIPA no subtrópico brasileiro. A presença do pastejo resultou em maior concentração de ortofosfato total e biodisponível (i.e., Mehlich-I) e também diminuiu a concentração de P orgânico, incluindo os inositol fosfatos. O pastejo aumentou a biodisponibilidade de P e reduziu a concentração de P orgânico recalcitrante (i.e., inositol fosfatos), portanto, concluiu-se que a integração entre lavoura e pecuária pode ser uma alternativa sustentável para aumentar o uso do P nos sistemas de produção no subtrópico brasileiro. O segundo objetivo específico foi analisar com meta-regressão (meta-análise), a dinâmica do P em diferentes texturas de solo e de clima em escala global, relacionando os grupos funcionais de P com o pH, concentração de C, relação CN e relação CP do solo em ecossistemas naturais. A composição de P orgânico teve uma resposta complexa à estas características do solo. A relação de monoesteres para o P orgânico aumentou com o aumento do pH, e diminuiu com o decréscimo da concentração de C, relação CN e relação CP, sem haver resposta particular para os locais e textura do solo. Em contraste, a relação de diesteres para o P orgânico bem como a relação diesteres para monoesteres teve o comportamento inverso, diminuindo com o aumento do pH, e aumentando com o aumento da concentração de C, relação carbono-nitrogênio (CN) e relação carbono-fósforo (CP). Portanto, concluiu-se que o pH, a concentração de C e as relações CN e CP são importantes fatores na determinação das proporções dos grupos funcionais de P orgânico do solo. O terceiro objetivo específico foi determinar a distribuição espacial de atributos do solo (textura e frações de C orgânico do solo) usando a combinação de espectroscopia de reflectância no infravermelho proximal (NIRS) e geoestatística, em um experimento de sistema agroflorestal localizado na Carolina do Norte, Estados Unidos da América. O NIRS foi uma ferramenta útil para predizer a textura do solo e as frações de C do solo. Na fase de calibração e validação do NIRS, o modelo de máquina de vetores de suporte teve uma performance melhor do que o modelo de mínimos quadrados parciais na predição das características do solo. A geoestatística aumentou os erros em relação àquales obtidos somente com o NIRS. Entretanto, a geoestatística possibilitou realizar a exploração das características espaciais da textura do solo e frações de C. A combinação do NIRS com a geoestatística pode ser utilizada para avaliação de atributos do solo deste sistema agroflorestal e de outros sistemas de produção, permitindo assim aumentar a sustentabilidade dos agroecossistemas através do manejo com agricultura de precisão. Palavras chave: integração lavoura-pecuária, plantio direto, ciclagem de nutrientes.
Abstract: Soil resources are narrowing as human evolution occurs and the negative feedbacks resulting from soil misuse are affecting agriculture's sustainable development worldwide. Therefore, alternatives that allow a more sustainable use of soils are necessary, to fill demands of the 21-century agriculture. The general objective of this thesis was to evaluate soils of agricultural systems that pursue sustainable intensification and natural ecosystems as a step to understand complex nutrient dynamics, which knowledge might help to adapt management by agriculture. It was studied the soil phosphorus compounds on integrated crop-livestock systems in Subtropical Brazil and on natural ecosystems across the world and soil organic carbon (C) dynamics in an agroforestry system on a Coastal Plain in United States of America. The first specific objective was to determine soil P composition from agro-ecosystems with low and high trophic complexity. Specifically, we wanted to qualify and quantify soil organic and inorganic P fractions using NaOH-EDTA extraction and nuclear magnetic resonance spectroscopy, and characterize P cycling in response to increasing complexity with integrated crop-livestock systems in subtropical Brazil. Our results were that in these agro-ecosystems, grazing compared with nograzing had greater soil P content as total and bioavailable (i.e., Mehlich-I) orthophosphate and lower soil organic P and fewer monoesters, including inositol phosphates. Grazing increased P bioavailability and reduced recalcitrant organic P (i.e., inositol phosphates) concentration in soil; therefore, we conclude that integrating crop and livestock systems can be a sustainable alternative to improve P use in farming systems of subtropical Brazil. The second specific objective was to analyze through meta-regression, soil organic phosphorus dynamics among different soil textures and locates at global scale, relating its organic functional groups with soil pH, C concentration, carbon-to-nitrogen (CN) ratio and carbon-to-phosphorus (CP) ratio on natural ecosystems. We found that soil organic P composition had a complex response to those soil characteristics. Monoesters-to-organic P ratio increased as pH increased, and decreased as C concentration, CN ratio and CP ratio increased, with no particular response among locates and soil textures. In contrast, diesters-to-organic P ratio as well as diesters-to-monoesters ratio had the opposite behavior, decreasing its concentrations as pH increased, and increasing as soil C concentration, CN ratio and CP ratio increased. Therefore we concluded that soil pH, C concentration, CN ratio and CP ratio are important factors in determining proportions of soil organic P functional groups. The third specific objective was to determine the spatial distribution soil properties (soil texture and organic C fractions) using a combination of near infrared spectroscopy and geostatistics, in an emerging agroforestry system experiment on a Coastal Plain site in North Carolina. Nearinfrared spectroscopy was a useful tool to predict soil texture and soil organic carbon (SOC) fractions. Using chemometrics to calibrate NIRS, a support vector machine model performed better than a partial least squares model to predict soil texture (sand and clay) and SOC fractions (total, particulate, and mineralizable C determined as the flush of CO2-C following rewetting of dried soil). Geostatistics increased errors of soil properties compared to those obtained solely by NIRS prediction. Nonetheless, geostatistics was useful to explore spatial patterns of soil texture and SOC fractions. Combining NIRS and geostatistics can be promoted for soil evaluation of this agroforestry system and in other landscapes to increase sustainability of agroecosystems through field-specific precision management. Key words: mixed crop-livestock, no-tillage, nutrient cycling.
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Sommerville, David W. "Phosphorus fertilization : effects on asparagus yield, and soil microbial parameters." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80876.
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Asparagus (Asparagus officinalis) is a perennial crop well suited to grow in Quebec. Despite high demand for this crop, asparagus production is declining because of asparagus root rot disease that is caused by Fusarium spp. Phosphorus is one of the most important nutrients for the production of healthy asparagus roots that may resist infection by Fusarium. The objective of this study was to determine the effects of phosphorus (P) applications on asparagus yield and soil microbial parameters. Plots receiving 0 to 200% of the P recommendation, based on the Centre de reference en agriculture et agroalimentaire du Quebec (CRAAQ) guidelines, did not differ significantly (p < 0.05) in first year yield or plant tissue concentrations. However, asparagus receiving no fertilizer had 2 to 3 times higher arbuscular mycorrhizal colonisation of roots than other treatments in May 2003. Fresh marketable yield was negatively correlated to Fusarium incidence (p = 0.0091 r = -0.51) suggesting that plants with higher yields are less susceptible to Fusarium symptoms and that producers should avoid over-harvesting low yielding plants to reduce Fusarium spread in the field. Soil microbial activity was not affected consistently by P fertilizers because of high variability in the field.
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Shumaker, II Paul D. "INORGANIC AND ORGANIC PHOSPHORUS INTERACTIONS WITH HYDROXY-INTERLAYERED SOIL MINERALS." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_theses/532.
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Phosphorus (P), a necessary plant and animal nutrient, can also lead to eutrophication of fresh waters when in excess. Appropriate P management is necessary to prevent fresh water pollution. Mineralogy of soil clays has been shown to affect P adsorption, desorption, and movement through soils. Specifically, hydroxy-interlayered minerals have been shown to adsorb and retain inorganic P in soil systems. This study was designed to determine the sorption and desorption characteristics of inorganic, organic, and mixed forms of P interacting with soil hydroxy-interlayered vermiculites (HIV) and smectites (HIS), and compare the findings to sorption and desorption processes of natural aluminum (Al) and Iron (Fe) hydroxide minerals. Results indicate natural Al and Fe hydroxide minerals sorbed and retained P more strongly than hydroxy-interlayered minerals in our samples and inositol hexakisphosphate was more highly sorbed and retained than inorganic P.
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Peat, Darren Michael William. "Modelling and monitoring of phosphorus transport and speciation in soil." Thesis, University of Plymouth, 1998. http://hdl.handle.net/10026.1/1270.
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Flow through soil into groundwater has been classically conceptualised as taking place through a set of aligned capillary tubes. In solute transport models these approximations are also present. Pore-Cor (a network model) has been used to model the void structure of soil by using water retention and mercury porosimetry curves. The model successfully predicts trends in saturated hydraulic conductivity. The effect of the assumptions used in the Pore-Cor geometry have been investigated by comparing of two dimensional slices of the simulated networks with two dimensional image analysis data. The geometric limitations of the model cause packing inefficiencies which prevent the model from representing the size distribution of voids found in real samples. The observation of environmental events is dependent upon the implementation of rapid and reliable analytical techniques. This work presents an adaptation of an FI method for the determination of dissolved reactive phosphorus (DRP) and a new method for the determination of total dissolved phosphorus (TDP). Both are ideally suited to the detection of phosphorus species in soil leachate and runoff waters over the concentration range 3 to 1000 Ilg ri. The effect of compaction on solute transport is described and the experimental data have been modelled using a modified form of the convection dispersion equation (CDE). The parameters of the CDE have been given structural interpretation by the network model. The model was used to interpret a change in dispersivity and the behaviour of reactive phosphorus species on compaction.
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Yusran, Fadly Hairannoor. "Soil organic matter decomposition : effects of organic matter addition on phosphorus dynamics in lateritic soils." University of Western Australia. School of Earth and Geographical Sciences, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0120.
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[Truncated abstract] Relationships between the persistence of organic matter added to soil, the dynamics of soil organic carbon (C) and phosphorus (P) were examined in four experiments on lateritic soils of Western Australia. The main objective was to quantify the release of P following organic matter application in soils which have high P adsorbing capacity. Another objective was to confirm that due to its recalcitrant materials, the effect of peat lasted longer in soil than other sources of organic matter in terms of increasing plant-available P fractions. Three experiments were conducted under glasshouse conditions for various lengths of time, with nine- to twelve-month incubations to investigate these hypotheses. As expected, organic matter with lower C:N ratios than peat (lucerne hay) decomposed more rapidly compared with peat, and the most active mineralisation took place within the first three months of incubation. Soil organic-C (extracted by 0.5 M K2SO4) had a significant positive correlation with P extracted with 0.5 M NaHCO pH 8.53. For a higher application rate (120 ton ha-1), peat was better than wheat straw and lucerne hay in increasing extractable bicarbonate-P concentrations in soil, especially at incubation times up to 12 months. Throughout the experiment, peat was associated with a steady increase in all parameters measured. In contrast to peat, nutrient release from lucerne hay and wheat straw was rapid and diminished over time. There was a tendency for organic-C (either in the form of total extractable organic-C or microbial biomass-C) to steadily increase in soil with added peat throughout the experiment. Unlike wheat straw and lucerne hay, extractable organic-C from peat remained in soil and there was less C loss in the form of respiration. Therefore, peat persisted and sequestered C to the soil system for a longer time than the other source of organic matter. Freshly added organic matter was expected to have a greater influence on P transformation from adsorbed forms in lateritic soils than existing soil organic matter. By removing the existing soil organic matter, the effect of freshly applied organic matter can be determine separately from that of the existing soil organic matter for a similar organic-C content. In order to do this, some soil samples were combusted up to 450° C to eliminate inherent soil organic matter. The release of P was greater when organic-C from fresh organic matter was applied to combusted soils than in uncombusted soils that contained the existing soil organic matter. The exception only applied for parameters related to soil micro-organisms such as biomass-C and phosphatase. For such parameters, new soil organic matter did not create conditions favourable for organisms to increase in activity despite the abundance of organic matter available. More non-extractable-P was formed in combusted soils compared to bicarbonate-P and it contributed to more than 50% of total-P. As for the first experiment, peat also showed a constant effect in increasing bicarbonate extractable-P in the soil
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Makris, Konstantinos Christos. "SOIL AND COLLOIDAL PHOSPHORUS DYNAMICS IN THREE KY SOILS: BIOAVAILABILITY, TRANSPORT AND WATER QUALITY IMPLICATIONS." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/408.
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Particulate P constitutes a significant portion of the total P found in surface runoff water. Water dispersed P-containing particles can travel long distances via surface runoff and reach water bodies causing decrease in water quality. The main objective of the study was to evaluate the potential facilitation of P transport by the water dispersed soil colloids (WDC) using three KY soils with a long-term record of poultry manure, and fertilizer P applications. Sequential fractionation for both whole soils and colloidal samples revealed that the WDC had a greater total and labile P content than the soil as a whole. Also, application of manure and fertilizer P seemed to decrease colloidal organic P fractions and increase the inorganic P fractions over the period of a growing season (May to September). Laboratory settling kinetics experiments were set up for the clay-colloidal fractions of the soils. It was shown that particulate P fractions paralleled WDC settling kinetics whereas dissolved P fractions remained in solution even after 36 hours. Field taken intact soil cores were leached with colloidal suspensions to test the effect of WDC on the vertical P movement. Results illustrated the preferential flow of particulate P though the macropores. When water was applied to the manure amended soil, dissolved P levels increased significantly over the control. WDC additions lowered dissolved P levels to the manure-amended columns, by sorbing to the WDC particles, but still greater than the dissolved P levels of the columns that had not been applied with manure.
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Ron, Vaz Maria Dolores. "Characterization of phosphorus in solutions from temperate soils." Thesis, University of Aberdeen, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261327.
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An analytical protocol for the determination of various soluble P fractions, namely: total dissolved P (TDP), dissolved reactive P (DRP), dissolved organic P (DOP) and dissolved condensed P (DCP) has been developed. The determination of DOP in soil solutions and water extracts was achieved by an improved automated photo-oxidation procedure, in which possible interferences caused by aluminium have been overcome. Partitioning of TDP into DRP, DOP and DCP fractions increased our understanding of P cycling in temperate soils. A combination of field and laboratory studies indicated that management factors such as soil acidity and fertiliser P additions greatly influenced the amount and distribution of soluble P between fractions. Natural climatic processes such as freeze/thaw and wetting/drying cycles have been shown to greatly affect soil P cycling. Fractionation of TDP into DRP, DOP and DCP components highlighted the problems associated with attributing the `freezing and drying effect' to any single process. The significance of these observations are discussed in terms of plant nutrition and possible contribution to P leaching and surface water quality.
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Unruh, B. L., J. C. Silvertooth, A. J. Steger, and E. R. Norton. "Nitrogen, Phosphorus, and Potassium Uptake by Upland and Pima Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1994. http://hdl.handle.net/10150/209649.
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Several investigations of nitrogen (N), phosphorus (P), and potassium (K) uptake by Upland cotton (Gossypium hirsutum L.) have been conduced, however no investigations of this type have included American Pima cotton (G. barbadense L.). We conducted a study to describe the total N, P, and K uptake and the partitioning of each nutrient into various plant parts for both Upland and Pima cotton. During the growing seasons of 1990, 1991, and 1992 at two south-central Arizona locations, both Upland (var. DPL 90) and Pima (var. S-6) cotton were grown. Beginning 14 to 20 d after emergence, whole cotton plants were removed and cotton plants were separated into stems, leaves (including petioles), burs (carpel walls), lint, and seeds. The bur fraction, also included squares, flowers, immature bolls, and burs from mature bolls. The appropriate analyses for total N, P, and K were determined on each fraction (except lint). Regression analyses was used to model nutrient uptake as a function of both days after planting (DAP) and heat units after planting (HUAP). Regression analyses indicated that HUAP was equally good, and in most cases superior to using DAP to model total nutrient uptake and partitioning within both Upland and Pima cotton. In every case there was close agreement between the predicted and actual total nutrient uptake. For Upland cotton the actual total N, P, and K uptake was 199, 29, and 250 kg ha⁻¹ and the predicted total N, P, and K uptake was 199, 29, and 255 kg ha⁻¹, respectively. For Pima cotton the actual total N, P, and K uptake was 196, 29, and 215 kg ha⁻¹ and the predicted was 210, 29, and 229 kg ha⁻¹, respectively. The pattern of nutrient partitioning in Upland cotton were similar to the findings of others and Pima showed the same general patterns of partitioning as Upland cotton. Seeds were a major sink of nutrients. Nutrient uptake in seeds resulted in decreasing uptake in leaves and stems. Presumably, due to mobilization of nutrients from those parts to the seeds during seed development. The nutrient requirements to produce 100 kg lint ha' for Upland cotton was 15, 2.2, and 19 kg ha⁻¹ for N, P, and K, respectively and was 20, 3.0, and 22 kg ha⁻¹, respectively for Pima cotton.
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Thelander, A. S., and J. C. Silvertooth. "Soil Test Calibration Evaluations for Phosphorus on Upland and Pima Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 2000. http://hdl.handle.net/10150/197512.
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Numerous field experiments were conducted at a wide range of sites in Arizona from 1988 through 1999 involving phosphate (P) fertilization of cotton (Gossypium spp.). A total of 21 site-years were used to study the effects of P on both Upland (G. hirsutum L.) and Pima (G. barbadense L.) varieties. The purpose of these experiments was to evaluate University of Arizona (UA) soil fertility guidelines with respect to soil test results (NaHCO3 extractable P) and to possibly fine-tune or calibrate these guidelines in relation to soil test P, applied P, and yield for common Arizona soils used in cotton production. Results from these experiments, based on soil test information, plant measurements, and lint yield showed no significant difference (P 0.05) due to treatments for all the studies with the exception of one P study conducted in Graham County in 1998 and another P study conducted in Pinal County in 1999. The 1998 Graham County site had a preseason soil test value of 7.6 ppm NaHCO₃ extractable P. The 1999 Pinal County site had a preseason soil test value of 3.0 ppm NaHCO3 extractable P. Analysis of yield results vs. soil P show that soil test P levels greater than 5 ppm are consistently sufficient for both Upland and Pima cotton. Yield results vs. applied P (lbs. P₂O₅/acre) for both Upland and Pima did not indicate a positive response over the rates of fertilization tested (20-160 lbs. P₂O₅/acre). Based on the results from these studies, the current UA soil fertility guidelines for P fertilization of cotton appear to be valid. Furthermore, the data indicates that the UA soil fertility guidelines may be further refined to provide the following categories: < 5 ppm = high probability of response to an added P fertilization; 6-10 ppm = medium probability of response to an added P fertilization; and > 10 ppm = low probability of response to an added P fertilization.
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SanClements, Michael. "The Chemistry of Acidic Soils in Humid, Temperate Forested Watersheds with Emphasis on Phosphorus, Aluminum and Iron." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/SanClementsM2009.pdf.
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Turner, Benjamin Luke. "Solubilisation and leaching of phosphorus from grassland soils with particular reference to the role of biological mechanisms and organic phosphorus." Thesis, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367889.
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Nieuwenhuis, Jenifer M. "Nitrogen and phosphorus modification within a petroleum contaminated biopile at the Oneida County Sanitary Landfill /." Link to abstract, 2004. http://epapers.uwsp.edu/abstracts/2004/Nieuwenhuis.pdf.
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Casteel, Shaun Nathan. "Phosphorus Dynamics from Broiler Breeder Diets in Manure, Soil, and Corn." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-04232009-112606/.
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Studies of broiler breeder diet modifications to reduce phosphorus (P) excretion have evaluated bird performance, but no studies have quantified the effects of P in the manure and the impacts to soil and plant availability once soil-applied. Four diets were formulated by factoring two levels, 0.40 and 0.22% available P (NRC, Low, respectively), with or without phytase during the breeder laying phase (wk 22 to 64). Breeders fed phytase produced manures with 15% lower total P concentration, but did not change manure water-soluble P (WSP). However, P in the breeder manures was > 92% orthophosphate. The incubation of the four unique manures in samples of Portsmouth (Typic Umbraquult) and Wagram (Arenic Kandiudult) series generally did not differ in concentrations of Mehlich-3 P, soil WSP, total inorganic P, and total P. Phosphorus-based applications of breeder manures (NRC, Low) and triple superphosphate (TSP, Ca[H2PO4]2 H2O) were applied to a P-deficient, Portsmouth soil in the greenhouse to determine the response of corn (Zea mays). Corn growth was equal among P sources in the initial study, but it tended to be greater in the soils amended with breeder manures in the residual study due to the P applied and the apparent liming effect of the soil. The NRC and Low breeder manures were applied at 39 kg P ha-1 in 2007 at Salisbury (Typic Rhodudult), Lewiston (Aquic Paleudult), and Plymouth (Typic Umbraquult), which ranged in soil P levels. Plymouth included TSP and an untreated control. Corn growth was equal among soils amended with the breeder manures NRC and Low in all site-years and grain P removal was equal five out of six site-years. Grain production, grain P removal, and applied P recovery were equal among P sources in 2007, but the breeder manure treatments were greater than TSP in 2008. Breeder manures should be considered equivalent to TSP in P impacts to the soil and plant availability.
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Gowing, David. "High soil phosphorus availability and the restoration of species-rich grassland." Thesis, Cranfield University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397456.
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Massey, Paul Andrew. "Interactions between phosphorus fertilisation and soil biota in managed grasslands systems." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7844.
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The application of phosphorus (P) fertilisers to grassland systems is a common practice to increase and sustain grassland productivity. This is requisite for satisfying the nutritional needs of grazing animals and increasing dairy and livestock output. The costs of such fertilisers are increasing and the demands for such fertiliser will also most likely rise following governmental targets set in Ireland to increase national agricultural output. However, the application of P fertiliser to grassland systems can contribute to the eutrophication of water-courses, since fertiliser applications can result in the accumulation of P at the soil surface. One potential way to facilitate plant P acquisition in grasslands may be associated with the soil biota. In particular, the soil microbial biomass is recognised as a potential P pool that can provide a source of bioavailable P to the plant community. The soil biota may also facilitate the incorporation of P from the soil surface into the soil profile, since earthworms can actively increase the transport of P-rich soil material from the surface belowground. This project thus aimed to discern how P fertilisation affects microbial biomass nutrient pools and biologically-mediated P incorporation in grassland systems, and how this relates to plant P yields. To investigate this aim, two research questions were proposed: (i) is the soil biota affected by commonly adopted P fertiliser strategies in grassland systems?; (ii) what consequence does this hold for P acquisition by the plant community? An experiment was conducted to examine how the soil biota responded to different rates of inorganic P fertilisation in two grassland sites of contrasting soil types over an 18 month period. This revealed that increasing P fertilisation did not affect microbial biomass P concentrations in the soil. However, an effect was observed upon plant P yield, in which greater plant P yields were obtained proportional to the P fertiliser rate. Two laboratory experiments were conducted to further investigate this lack of effect. These utilised soil from the same grassland sites and examined how nutrient additions to the soil affected microbial biomass nutrient pools and activity. Results from these experiments supported evidence from the field experiment, since the application of P fertiliser did not affect microbial biomass nutrient pools following fertiliser application, and supplementation of carbon (C) + P substrate to the soil did not invoke respiratory responses between P fertiliser treatments. Nevertheless,supplementation with C + nitrogen (N) and C+N+P substrates was found to suppress microbial respiration. This was attributed to greater C assimilation by the microbial community in these particular substrate-induced respiration treatments. In order to investigate biologically-mediated P incorporation, a glasshouse-based mesocosm scale experiment was carried out using two contrasting soils. Bulk soil (1 – 30 cm depth range) was derived from a nutrient poor grassland system, whereas the soil for the 0 – 1 cm depth range was taken from an intensive system that was seven times greater in labile inorganic P concentration. Three treatments were applied to mesocosms in an incomplete factorial design, involving the inclusion of earthworms, different botanical diversities (unplanted, monoculture or mixed plant community) and different fertiliser types (organic or inorganic). The absent factorial combinations involved the application of earthworms to unplanted mesocosms. With respect to the earthworm treatment, results revealed that the presence of earthworms reduced labile P concentrations in the 0 – 1 cm depth range of soil. The presence of different botanical diversities or fertiliser types did not affect microbial biomass nutrient pools, whilst the presence of mixed plant communities did increase plant P yields. However, microbial and nematode community structures were affected in an idiosyncratic manner by both botanical diversity and fertiliser type. This project demonstrated the significance of grassland management regimes in governing microbial biomass P concentrations. In particular, it was revealed that the frequent defoliation of the sward appeared to uncouple the microbial community from both fertiliser inputs and possibly plant P yields. The fact that an increase in plant P yield with increasing P fertilisation was noted in the absence of microbial responses suggests that the soil biota may not be crucial for plant P acquisition in such intensive inorganic-fertiliser based regimes. This suggestion was also supported by the mesocosm experiment, since plant P yields differed between botanical diversities but no effects were observed on microbial biomass P concentrations. Furthermore, this project showed the potential of the earthworm community to reduce P concentrations in the volume of soil which poses the greatest risk to water quality. The collective evidence highlights the need for further understanding of the consequences of inorganic-based fertiliser management systems, since current strategies may not adequately account for management effects on soil biological P cycling.
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Peters, Anna L. "The Effects of Soil Phosphorus on Acer rubrum Fecundity." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1398164024.
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Seiler, Lauren Katherine Kaye Jason P. "Exploring potential soil phosphorus movement in four organic agriculture forage systems." [University Park, Pa.] : Pennsylvania State University, 2009. http://honors.libraries.psu.edu/theses/approved/WorldWideIndex/EHT-44/index.html.
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Tickes, Barry R., and Tom Doerge. "Survey of Soil Phosphorus in Established Alfalfa Fields in Yuma County." College of Agriculture, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/201365.
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A survey was conducted to evaluate the soil phosphorus levels in a cross section of established alfalfa fields in Yuma County The levels of extractable phosphorus (P) varied from 3 to 43 ppm P. All of the soils testing in the very low (below 5 ppm P) and low categories (5 -10 ppm P) were located in the Wellton-Mohawk Valley and on the Yuma Mesa. Annual soil testing in the fall should be used to identify fields which would be expected to be responsive to P fertilizer applications. Soil testing could also help identify fields less like& to respond to P additions (P values > 15 ppm). Eighty percent of the fields tested from the Yuma and North Gila Valleys were in the high and very high ranges, 16-25 ppm and > 25 ppm P respectively. These high values may reflect residual P from applications of phosphorus fertilizers to vegetable and cotton crops grown in rotation with the current alfalfa crops. Fall soil testing in these areas could help identify nonresponsive fields in order to avoid unneeded P applications.
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Notodarmojo, Suprihanto. "Modelling phosphorus transport in soil and groundwater with two consecutive reactions." Thesis, Notodarmojo, Suprihanto (1992) Modelling phosphorus transport in soil and groundwater with two consecutive reactions. PhD thesis, Murdoch University, 1992. https://researchrepository.murdoch.edu.au/id/eprint/51421/.
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A one-dimensional model of phosphorus transport in soils and groundwater applicable for steady state or transient unsaturated waterflow conditions has been developed. Convective transport, hydrodynamic dispersion and time-dependent phosphorus sorption are accounted for in the model formulation. Time-dependent sorption of phosphorus is considered to follow the empirical model of Barrow and Shaw (1979), which can be described by S = k.Cnt.m The assumed sorption model allows model parameters to be obtained by independent batch and column experiments.
Numerical techniques were used to solve the solute transport equations. For the steady state model, a correction to the numerical dispersion to improve the numerical solution is presented. Analytical solutions for a simplified case are also presented and used to test the numerical solution. For the transient mode 1, numerical solutions of water and solute transport are tested against published data. Parameter sensitivity analysis conducted for the steady state model shows that influent concentration and the parameter k strongly affect the initial breakthrough time for the solute.
The above solute transport equations which assume that the contact time between the entire soil in the column and solute starts when the solute is introduced into the column are also corrected for, by initiating the contact time for every segment in the column when the soil solution is greater than zero. Numerical solutions of the solute transport equations with corrected and non-corrected contact time are also compared. For the range of laboratory soil column experiments, it was found that the difference is small.
Batch experiments and miscible displacement experiments using soil column techniques and sectioned columns were conducted to verify the applicability of the model. For steady state condition, P transport under saturated and unsaturated waterflow conditions were examined. Miscible displacement experiments using soils which had been previously waterlogged for 30 days to see the effect of waterlogging were also conducted. For transient waterflow condition, solute and water transport during infiltration was investigated. Gavin and Joel sandy soils from the Bassendean soil system (Western Australia) and 3 different volcanic soils from Bandung (Indonesia) were used.
Experimental results show that Barrow and Shaw's sorption model can be used to describe phosphorus sorption in batch experiments. The transport model formulated in this study adequately describes the movement of phosphorus in Australian sandy soils, and one of the Indonesian soils. The steady state model, however, fails to simulate the phosphorus movement in other Indonesian soils. In most cases, experimental breakthrough lags behind theoretical curve. The failure of the model is due to the different conditions between continuous miscible displacement experiment in the soil columns and batch shaking experiments. It is recommended that a procedure to carry out batch experiments which minimizes the effect of the presence of antecedent anions and soil-to-solution ratio be developed.
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Esberg, Camilla. "Phosphorus availability and microbial respiration across biomes from plantation forest to tundra /." Doctoral thesis, Umeå : Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-33732.
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Dell'Olio, Laura Ashley. "Refining the Phosphorus Loss Assessment Tool for the Organic Soils of North Carolina." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-10262006-141107/.
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Phosphorus (P) runoff and leaching from agricultural fields have been identified as major environmental concerns for the health of aquatic ecosystems. North Carolina has responded by implementing the Phosphorus Loss Assessment Tool (PLAT). The goal of the PLAT is to determine relative P losses from agricultural fields based on several site factors and characteristics, including Mehlich-3 P (M3P) soil test values. Based on previous research, the current version of PLAT is programmed to predict greater soluble P losses from organic soils than from mineral soils with the same M3P values. However, recent research specific to North Carolina?s organic soils has indicated decreased soluble P release in the presence of high Al concentrations. Our objectives were to determine (i) the Al content of Typic Haplosaprists and Terric Haplosaprists of North Carolina?s Lower Coastal Plain, and (ii) how the Al in these soils affects P retention. We sampled four organic soil series and determined M3P, Mehlich-3 Al (M3Al), Mehlich-3 Fe (M3Fe), water-soluble P (WSP), total P, pH, particle size distribution, and the organic matter content (OM). Water-soluble P and M3P were also measured in a 21-d incubation study in which P was added at a rate equivalent to 150 kg P ha-1. Total CuCl2 extractable Al and inorganic soil P fractions were identified in an Al and inorganic P fractionation study, respectively. According to the results of the incubation, multiple regression, and fractionation studies, Al was the main cation responsible for P retention; the mean topsoil M3Al concentrations (1926 mg kg-1) in these organic soils were much higher than those observed in another study of mostly mineral NC soils. The concentration of M3Fe was low in every series and was not correlated to any P characteristics. Mehlich-3 P was not consistently correlated to P retention and WSP; however, OM, M3Al, and total CuCl2 extractable Al were correlated with P retention. In the incubation study, the percentage of applied P that was adsorbed was greater in soils with lower OM and/or higher M3Al. Increased OM was associated with increased WSP and lower total P, as well as decreased P retention. The opposite effect was observed with increasing M3Al concentrations; however, the ratio of OM to M3Al showed increased correlation to P retention and WSP than when OM and Al were used alone. These results indicate that soils with higher OM and lower Al did not retain P as well as soils with lower OM and higher Al contents. Furthermore, as more Al bound P was extracted by M3P (causing higher M3P/Al-P %), WSP increased, and coincided with decreased total CuCl2 Al. The results from this study show that in high OM soils, the concentration of extractable Al controlled the solubility of P. North Carolina?s PLAT could be modified to include M3Al concentrations to more accurately predict P losses in the organic soils of the lower coastal plain, thus potentially reducing P runoff and leaching into our aquatic ecosystems.