Phosphorus Concentration In Solution Research Articles

Effects of Excessive Application of P and Zn Fertilizer on Growth and Yield of Maize under Hydroponic Conditions

Background: Phosphate is an essential nutrient but can be toxic to plants when phosphate accumulates in plants at high levels. The objective of the study was to find effects of excessive application of P and Zn fertilizer on growth and yield of maize under hydroponic conditions. Methods: Research of Experiment studied from August to December 2019 at the greenhouse of the Agriculture and Aquaculture School at Tra Vinh University. The study aimed to determine the effect of high phosphate application on growth, biomass, symptoms of poisoning, phosphate and zinc absorption in maize and vegetables grown in hydroponic solution. Result: Experimental results showed the symptoms of phosphate poisoning on maize when grown in Hoagland nutrient solution (2.0 mM P) with an additional phosphorus content of 0.1 mM P, 1.0 mM P, 3.0 mM P in the treatment with or without the addition of Zn. However, the poisoning symptoms have been yet clearly expressed when Zn was not added. Therefore, plants may exhibit phosphorus toxicity, reducing Zn absorption when the phosphorus concentration in solution was increased by more than 1%P2O5. It is necessary to continue investigating plants’ responses to phosphate fertilizers.

Directional conversion and removal of complex phosphorus compounds from acidic leaching solution containing vanadium

Deep phosphorus removal from acidic leaching solution containing vanadium is a challenging problem due to the formation of complex phosphorus compounds. This problem can be possibly solved by proposed hydrogen peroxide coupled with iron-aluminum mixed salts, in which complex phosphorus compounds can be directionally converted and removed. Under the optimal conditions (the mole ratio of Fe/Al/P at 1.25:0.40:1.00, initial pH value at 5.00, reaction time for 1 h, reaction temperature at 70℃, the mole ratio of H2O2/P of 20:1), the phosphorus removal efficiency and vanadium loss rate were 99.29 % and 5.96 %, respectively. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy were used for characterization analyses of phosphorus in the removal products. Results indicated that hydroxyl radicals (·OH) made the directional conversion of complex phosphate radicals to PO43-. Complex phosphorus compounds were eventually removed in the form of PO43-. An efficient phosphorus removal progress was obtained. The concentration of residual phosphorus in solution was only 3.7 mg/L, and the mole ratio of vanadium to phosphorus in solution changed from 18 to 2353.

Hydrogen peroxide coordination-calcium salt precipitation for deep phosphorus removal from crude sodium tungstate solution

In the traditional alkali smelting process of tungsten ore，a small amount of the associated phosphorus will enter the sodium tungstate solution. In order to produce a qualified tungsten product, phosphorus must be removed in depth. Conventional methods for removing phosphorus, such as magnesium salt precipitation, ion exchange, etc., are difficult to efficiently remove high concentrations of phosphorus from sodium tungstate solution. In this paper, a method for deep phosphorus removal from crude sodium tungstate solution by hydrogen peroxide coordination‑calcium salt precipitation is proposed due to the coordination ability of hydrogen peroxide with tungstate to form peroxytungstate which is difficult to be precipitated by calcium. The paper mainly explores the theoretical feasibility of this method, the influence of time, calcium addition, pH value, initial phosphorus concentration and other factors on P removal. The best phosphorus removal condition has been obtained: under the condition of adding hydrogen peroxide, when the reaction time is 10 min; the molar ratio of calcium to phosphorus added is 3; the pH value is 9.5, and the phosphorus concentration is higher than 1 g/L, the phosphorus removal effect has been basically stable. The phosphorus removal ratio can reach 99.9% which means that phosphorus concentration in solution is <10 ppm after phosphorus removal, and the tungsten loss is as low as 0.1%. This method can remove phosphorus deeply from sodium tungstate solution containing different initial phosphorus concentration.

Optimization of arsenic phytoremediation using Eichhornia crassipes

ABSTRACTThis study aimed to evaluate the pH, phosphate, and nitrate in the process of arsenic absorption by Eichhornia crassipes (water hyacinth), using the surface response methodology, in order to optimize the process. The plants were exposed to a concentration of arsenic of 0.5 mg L−1 (NaAsO2) over a period of 10 days. The results indicated optimal levels for the absorption of arsenic by E. crassipes at pH equal to 7.5, absence of phosphate, and minimum nitrate level of 0.0887 mmol L−1. For the tested concentration, E. crassipes was able to accumulate 498.4 mg kg−1 of As (dry base) in its plant tissue and to reduce 83% of the initial concentration present in the aqueous medium where it was cultivated. The concentration of phosphorus in solution linearly increased the phosphorus content in the plants and negatively influenced the absorption of arsenic. The concentration of 0.5 mg L−1 of As did not significantly affect the relative growth rate (RGR) and the tolerance index (TI). 94% of As (III) initially solubilized in water was converted by the end of the experiment period into As (V). The water hyacinth was important in the phytoremediation of arsenic when cultivated under optimal conditions for its removal.

Effect of Solution Phosphorus Concentration on the Exudation of Oxalate Ions by Wheat (Triticum aestivum L.)

A solution culture experiment was conducted to investigate the effect of solution phosphorus concentration on the exudation of citrate and oxalate ions by five different varieties of the wheat (Triticum aestivum L). Wheat varieties were grown in a modified Hoagland nutrient solution containing five phosphorus levels (0, 0.2, 0.3, 0.4 and 0.5 μg/mL). Increasing the concentration of P significantly decreased oxalic acid exuded from roots. The exudation of oxalic acid was maximum at 10 days time interval. All the varieties of wheat were equally effective in exudating oxalic acid. The time interval had no significant effect on P concentration in plants. But significant interactive effect on plant P was found between varieties and different time intervals. Five levels of solution phosphorus (0, 0.2, 0.3, 0.4, 0.5 µg/mL) affected the oxalic acid secretion in wheat crop. The concentration of oxalic acid decreased with the increased levels of phosphorus concentration. In phosphorus stress condition wheat seedling secreted higher amount of oxalic acid.

Overcoming the Confounding Effects of Salinity on Sodic Soil Research

The adverse effects of sodicity on plant growth are difficult to quantify using naturally occurring soils because of the confounding variation in other soil properties, particularly salinity, pH, organic matter, soil nutrients, mineralogy, and texture. We applied a method involving the equilibration of large soil volumes with solutions varying in sodium adsorption ratio (SAR), followed by excess salt removal with solutions of similar SAR but lower ionic strength. Application of this method to a calcareous nonsodic, nonsaline Vertosol from Narrabri, New South Wales, resulted in soils with exchangeable sodium percentage (ESP) values between 2% and 25% but with similar magnesium and potassium concentrations and constant electrical conductivity (∼2.7 dS/m). Soil pH and solution phosphorus concentrations automatically increased as the ESP of the soil rose, which is important to consider when addressing plant growth results. This method can successfully minimize the confounding of sodicity with other soil properties that so often plagues sodic soil research.

14C]Glyphosate transport in undisturbed topsoil columns

Although glyphosate (N-(phosphonomethyl)glycine) is one of the most frequently used herbicides, few controlled transport experiments in undisturbed soils have been carried out to date. The aim of this work was to study the influence of the sorption coefficient, soil-glyphosate contact time, pH, phosphorus concentration and colloid-facilitated transport on the transport of [14C]glyphosate in undisturbed top-soil columns (20 cm height × 20 cm diameter) of a sandy loam soil and a sandy soil. Batch sorption experiments showed strong Freundlich-type sorption to both soil materials. The mobility of glyphosate in the soil columns was strongly governed by macropore flow. Consequently, amounts of glyphosate leached from the macroporous sandy loam soil were 50–150 times larger than from the sandy soil. Leaching rates from the sandy soil were not affected by soil-glyphosate contact time, whereas a contact time of 96 h strongly reduced the leaching rates from the sandy loam soil. The role of pH and phosphorus concentration in solution was relatively unimportant with respect to total glyphosate leaching. The contribution of colloid-facilitated transport was <1 to 27% for the sandy loam and <1 to 52% for the sandy soil, depending on soil treatment. The risk for glyphosate leaching from the top-soils seems to be limited to conditions where pronounced macropore flow occurs shortly after application. © 2000 Society of Chemical Industry

256 Evaluation of Phosphate Desorption Characteristics of Clay Minerals for Soilless Root Media

Soilless root media retain very little phosphate. This characteristic necessitates continual application of phosphate, which leads to excessive application and leaching. The phosphate desorption characteristics of synthetic hematite (a-Fe2O3), goethite (a-FeOOH), allophane (Si3Al4O12*nH2O), and a commercial alumina (Al2O3), previously determined for their maximum adsorption capacities, were evaluated to determine their potential for providing a low, constant soil solution phosphate supply with low phosphate leaching from soilless root media. The desorption isotherms of the clay minerals were obtained by introducing 10 mM KCl solution at 0.2 ml/min flow rate into a stirred flow reaction chamber loaded with clay adsorbed with phosphate at maximum adsorption capacity. The suspension in the reaction chamber was held at pH 6.4 during desorption. Effluent solutions were collected for phosphorus analysis until the equilibrium concentration of phosphorus in solution reached 0.05 mg•L-1. Adsorbed phosphorus at 0.05 mg•L-1 equilibrium concentration in solution was in the order allophane (19 mg•g-1) &gt; alumina™ goethite (8 mg•g-1) &gt; hematite (1.3 mg•g-1). The equilibrium concentration of phosphorus in solution over time showed that allophane releases phosphate for a longer time than the other clay minerals at a desirable soil solution concentration for plants, less than 5 mg•L-1. Among the clay minerals tested, allophane showed the most favorable potential to supply phosphate to plants in soilless root media.

Solubility equilibria controlling solution phosphorus concentration in minesoils in Galicia, Spain

Solution P control through dissolution/precipitation equilibria was studied in coal mine soils in Galicia, NW Spain. Soil solution was obtained by a column displacement method and analysed for pH, Eh, electrical conductivity, and most common anions and cations. Ionic activities were calculated using the program SOLMINEQ and saturation indexes determined for several phosphate minerals. Strengite, variscite, fluorapatite or MnPO 4.1.5H 2O appeared to control phosphorus solubility, depending on Eh, pH and ionic strength conditions.

Microbial effects in maintaining organic and inorganic solution phosphorus concentrations in a grassland topsoil

Replenishment of soil solution organic and inorganic P in a sterile and nonsterile grassland soil amended with 0 and 235 kg P ha−1 for 13 consecutive years was investigated in a recirculating column system. In sterilized treatments, P liberated from soil biomass, initially increased solution organic and inorganic P concentrations to about 0.3 and 0.6 μg P cm−3 in the 0 and 235 kg P treatment, respectively. Sterilization effects were larger than the residual fertilizer effect. Subsequently, in sterilized treatments were microbial activity was lacking, removal of solution P over the duration of the experiment reduced organic P concentration to the detection limit (0.001 μg P cm−3). Organic P concentrations in the nonsterile treatment were maintained at about 0.015 μg P cm−3 which was higher than inorganic P concentration. Inorganic P concentrations were about 0.002 and 0.008 μg P cm−3 in the nonfertilized and the fertilized treatment, respectively. Inorganic P buffer power was greater in the nonsterile treatments, but abiotic buffering alone could not account for the measured inorganic P concentrations found during desorption. It was concluded that biomass P is a major factor controlling organic and inorganic P solution concentrations in this systems.

The P fertilizer requirements of subterranean clover, and the soil P status, sorption and buffering capacities from two P analyses

The phosphorus fertilizer requirement of subterranean clover (Trifolium subterraneum) was determined on a number of soils in field and glasshouse experiments. The solution phosphorus concentration in a 0.01 M CaCl2 extract (SPC0) determined from a phosphorus sorption curve was found to be closely related (R2 = 0.80 to 0.84) to relative yield. The critical SPC required to achieve 90% of relative yield (SPCc) was 0-128 �g P mL-1 in the field and 0.106 �g P mL-1 in the glasshouse experiments. Phosphorus sorbed at an SPC of 0.10 �g P mL- l (Ps0.1 at SPC0.1) was highly correlated with the phosphorus requirement of subterranean clover in both the field and glasshouse, accounting for 89% and 73% respectively of the variation in phosphorus requirement. A modified two-point sorption curve was found to give a good estimate of phosphorus sorbed at both SPC0.1 (Ps0.1) and SPC0.3(Ps0.3), and greatly increased the number of soil samples that can be processed, compared with a five-point sorption curve. The two-point test involved the addition of solutions containing 0 and 8 �g P mL-1 at a soil: solution ratio of 1:10. The sorption curve constructed using this method was suitable for assessing soils with Ps0.1 levels up to 90 �g P g-1. The soil phosphate buffering capacity at SPC0.1 (PBC0.1) was also accurately estimated using calculations from the two data points, but PBC0.3 values were poorly estimated. It was concluded that the two-point sorption curve is a sensitive and efficient method of predicting the present phosphorus status of clover pastures, their phosphorus fertilizer requirements, and of calculating PBC0.1, a useful soil characteristic.

Evaluation of nutrient solution phosphorus concentration on potato plantlet tuber production under greenhouse conditions1

Abstract Phosphorus fertilizer management of greenhouse grown micropropagated potato plantlets has been based on field research. Differences in growing conditions, potting media and the planting material itself may make the field research data base unacceptable in a greenhouse environment. This study was conducted to determine the optimum nutrient solution phosphorus (P) concentration for maximum growth and yield of micropropagated potato plantlets grown under greenhouse conditions. Nutrient solution P concentrations ranging from 0 to 55 μg P/ml were evaluated. Each nutrient solution P concentration was applied weekly to micropropagated potato plantlets that were grown in 80% vermiculite‐20% sand potting medium. Results indicate that P concentrations between 10 and 35 μg P/ml are optimum for potato plantlet tuber production. This P concentration range maximizes vegetative weight, total tuber weight and number of tubers produced per micropropagated potato plantlet. Data further indicated that the potting medium retained and possibly accumulated P from the weekly applied nutrient solution. This enabled the plants, receiving relatively low nutrient solution P concentrations, to extract more P for proper growth and yield with time. To avoid unnecessary nutrient costs, the 15 μg P/ml nutrient solution concentration is recommended. This P concentration will produce maximum tuber yields and still allow for less than optimum management which may cause P conversion to unavailable forms. Additional studies should be conducted to correlate plant tissue concentration at different growth stages with final tuber yields.

Effects of Phosphorus Nutrition and Defoliation on C4 Graminoids from the Serengeti Plains

Kyllinga nervosa (Cyperaceae) and Digitaria macroblephara (Poaceae), C4 graminoids, were obtained from the Serengeti National Park of Tanzania. Kyllinga is most abundant on high pH, high calcium, low phosphorous, carbonatitic ash—derived soils, and Digitaria is more abundant on neutral, lower calcium, higher P soils. Both species come from intensely grazed grasslands. Plant responses to different nutritional levels and defoliation were measured to evaluate potential limiting interactions between energy and nutrient flows in grazing ecosystems. Plants were grown hydroponically at solution phosphorus concentrations of 10 and 100 μmol/L and were either unclipped or clipped weekly to a height of 3 cm for 5 wk. At that time, the kinetics of P uptake were measured with 32P, plants were harvested, and dry masses and the tissue concentrations of P and N were determined. Clipping and P concentration of the growth medium both had major effects upon yields of all plant components. Total yield of Kyllinga was highest in unclipped plants at high levels of P supply; yields under all other conditions were lower and indistinguishable from one another. In contrast, yield of Digitaria, which had been collected in areas with soils of higher phosphorus availability, was unaffected by defoliation but was almost 21/2 times greater when plants were grown at the higher P level. Root growth of Digitaria was stimulated by defoliation when P was abundant. Maximum yield to grazers from Kyllinga under conditions of this experiment would be achieved if grazers foraged only at the end of the period; maximum yield of Digitaria to grazers would be achieved if grazers defoliated plants at frequent intervals. A variety of morphological changes associated with maintaining similar leaf areas whether clipped or unclipped were associated with Digitaria's ability to compensate for simulated grazing. Yield to producers (the residual live biomass present at harvest) and yield to grazers were positively correlated, indicating that conditions promoting plant yield caused a proportional increase in yield to higher trophic levels. Maximum concentrations of P and N in the tissues of both species occurred in plants that were clipped and were grown at the high P level. N concentration was positively correlated with P concentration when plants were grown at high P, but was unrelated to tissue P concentrations when plants were grown at low P. That pattern reflects luxury N uptake of plants grown at low P. Nutrient uptake rate per unit root mass was higher in Digitaria than in Kyllinga. Defoliation stimulated nutrient uptake rate in both species, primarily due to decrease Km rather than changes in Vmax. Total P accumulation per plant (predicted from uptake rates measured with 32P, root mass, and nutrient mass, and nutrient solution P concentrations) was closely and positively correlated with measured P accumulation. However, P accumulation over the experiment fell far below predicted amounts. That disparity was likely due to low root biomasses early in the experiment and nutrient depletion between solution renewals.

Supernatant solution phosphorus concentrations required by five soybean (Glycine max) cultivars

Abstract Dry matter yields at flowering and seed yield responses of five soybean cultivars (Bragg, Semstar, Flegler, Davis and Wills) to six soil phosphorus levels in an Oxic Paleustalf were determined in a pot experiment. Ninety percent maximum dry matter yield at flowering was attained at the following supernatant solution P concentrations (determined from P sorption curves): Bragg, 0.012 μg ml‐1; Davis, 0.009 μg ml‐1; Semstar, 0.010 μg ml‐1; Flegler, 0.011 μg ml‐1; Wills, 0.012 μg ml‐1. Ninety percent maximum seed yield was attained at a supernatant solution P concentration of 0.007 μg ml‐1 by Bragg, Semstar, Flegler and Wills. Davis required 0.011 μg P ml‐1 for 90% maximum seed yield. It is concluded from these results that Bragg, Semstar, Flegler and Wills will have similar phosphorus fertilizer requirements, but Davis will require larger additions of phosphorus than the other cultivars for maximum seed yield.

Supernatant solution phosphorus concentrations required by some tropical pasture species

Abstract Using phosphorus sorption curves, the supernatant solution P concentrations corresponding to 90% maximum yield of Stylosanthes guianensis, Centrosema pubesoens, Panicum maximum (N fertilized) and Melinis minutiflora (in association with S. guianensis) were 0.037 μg ml−1, 0.048 μg ml−1, 0.029 μg ml−1 and 0.034 μg ml−1 respectively. These non‐limiting concentrations were used to assess the suitability of the species for soils differing in phosphorus status. The use of non‐limiting concentrations for estimating phosphorus fertilizer requirements of the species is discussed.

Kinetic Behavior of Phosphate Sorption by Acid, Sandy Soil

AbstractThe time dependency of phosphate sorption‐desorption in fertilized soil is particularly important to the efficiency with which plant roots absorb applied phosphorus from the soil solution. In this study, phosphorus sorption by two acid, sandy soils was measured with time using a laboratory batch technique for a range of initial phosphorus concentrations in solution. A comparison of experimental data with results calculated using a two‐site sorption‐desorption model showed that for contactimes &gt; 1 hour the observed phosphorus sorption in both these sandy soils could be described by assuming rapid and slow reversible reactions to occur simultaneously at two separate types of sorption sites. However, for shorter contact times (&lt; 1 hour) the 2‐site model did not describe the P sorption adequately. The orders of the forward reactions at the rapid and slow sorption sites were fractional and first‐order, respectively, with regard to the P concentration in solution. For a given soil, one set of rate coefficient values was sufficient to describe the solution phase concentration of P for several different initial concentrations.

The effect of titanium on phosphorus solubility in a Ni-Cr steel from a study of free-surface segregation

The rate of phosphorus segregation to the free surface of a low carbon Ni-Cr steel con-taining 0.06 wt pct P was found to be severely retarded at 833 K by the addition of 0.3 wt pct titanium to the alloy. The results indicate that the reported elimination of temper embrittlement in a phosphorus doped low carbon Ni-Cr steel, by a titanium addition, is due to inhibition of phosphorus segregation to grain boundaries because of removal of phosphorus from solid solution. An analysis of the segregation kinetics led to the con-clusion that the titanium addition lowered the concentration of phosphorus in solution to 0.012 ± 0.002 wt pct at 833 K. This was confirmed by experiments on a titanium-free al-loy containing 0.015 ± 0.0015 wt pct phosphorus.

A Centrifugal Filtration Method for Isolating Rhizocylinder Solution

AbstractTo measure the phosphate concentration in the soil solution adjacent to plant roots, a method of isolating the rhizocylinder solution was developed. A major factor in the choice of a method is that it should be rapid and should not alter the solution salt concentration during isolation. The centrifugal filtration method satisfies both conditions for bulk soil samples; it was subsequently applied to the rhizocylinder (roots plus adhering soil). Root sap leaking from corn (Zea mays. L) roots during centrifugation introduced a significant error in the rhizocylinder solution phosphate concentration for a sandy loam with a low solution phosphorus concentration. For two medium‐textured soils with a higher solution P concentration, the error was negligible. The method is considered suitable for the latter soils.

Solution Phosphorus Concentration and Growth of Rice (Oryza sativa L.) in Flooded Soils

AbstractSoil solution P concentration was monitored at weekly intervals during the vegetative growth of Rice (Oryza sativa L. var. ‘Bluebelle’) on flooded soils from the gulf coast region of Texas. Significant increases in dry matter production were obtained from application of phosphate fertilizer. Average soil solution P concentration ranged from 0.02 to 5.28 ppm when all soils and P fertilization rates were considered. A linear relationship was obtained between the logarithm of the average soil solution P concentration and the P concentration or P uptake of the plant. Yields were greater than 90% of maximum when the average soil solution P concentration was greater than 0.1 ppm. The concentration of P in the plant tissue at 0.1 ppm soil solution P was 0.25%.

Phosphate Retention by Iron and Aluminum in Cation Exchange Systems

Phosphate retention by a kaolinitic soil clay and cation exchange resins was studied to evaluate both the nature of retention and the effect of cations on the system. Calcium in the system always effected greater retention of phosphate by the exchange material than did sodium. Surface coatings of iron or aluminum on the exchange material were found to retain a large proportion of the added phosphate. The amount of this retention increased as the concentration of phosphorus in solution increased. The percentage of the retained phosphate that exchanged with radiophosphorus in solution was a function of both the concentration of phosphorus in solution and the length of time allowed for equilibration. In these reports both the coated resins and a soil clay acted similarly. Under the conditions of these experiments, the iron-coated resin was capable of retaining only slightly more phosphate than the aluminum-coated resin. However, in a mixed system most of the phosphate was retained by the iron-resin system. The results indicate that retention in these systems probably involves exchange of phosphate from solution with ions on the surface of the particles. The hydrous oxides of iron and aluminum are undoubtedly involved in this retention. The presence of other cations, Ca, Na, and H, affect the extent of this retention.