Phosphate solubilising bacteria

Most reports of the studies on solubilisatioh of phosphate in liquid culture and soil suggested that organic acids produced by microorganisms are responsible for promoting the dissolution of phosphate. Sperber (11, 12), Louw and Webley (7) and Duff, Webley and Scott (2) studied the production of acids by cultures of some phosphate dissolving fungi. actinomycetes and bacteria and observed that among the acids produced in liquid medium, hydroxy carboxylic acids such as lactic and 2-ketogluconic acids were responsible for solubilisation of phosphates. In the present studies, apart from the culture of Bacillus megaterium var. phosphaticum isolated from phosphobacterin which had been obtained from USSR. Indian strains of Bacillus megaterium, Bacillus circulans and Escherichia freundii isolated and identified by Sundara Rao and Sinha (13) were used. These studies were undertaken to find out different types of nonvolatile acids produced in Pikovskaya's (9) liquid medium.     

解磷菌剂对作物生长和土壤磷素的影响

利用课题组自行分离筛选的B2和B67解磷菌株研制的菌剂，在盆栽和大田试验过程中，菌剂在增加作物产量的同时，有提高土壤速效磷含量、培肥土壤的作用，而且是菌剂和化肥配合施用效果显著。施用了解磷菌剂或菌剂和化肥配合施用后，盆栽玉米的株高、鲜重和干重，较CK增加15．2％～89．2％，玉米单株吸养量较CK增加20％～146％；青菜的鲜重、干重和生物量较CK增加15．8％～41．6％，和CK比较差异显著；小麦的株高、有效小穗数、穗粒数、粒重以及生物量也较CK差异显著，大田试验的几种作物也有不同程度的增产。另外B2和B67接种到山西省典型土壤中，土壤速效磷含量较CK增加1．35～3．04倍，且发现其溶磷效果和土壤磷酸酶活性与有效活菌数相关，解磷菌剂在提高土壤速效磷含量的同时，也有提高土壤速效钾含量的作用。     

Phosphate Sorption Isotherms Revisited

A criterion is proposed for assessing ranges of validity of equilibrium isotherms for phosphate sorption by soils. This criterion is based on the geometrical features commonly exhibited by such isotherms and is analogous to the one that was first formulated by Aharoni and Ungarish in connection with the kinetics of chemisorption reactions. Its use with equilibrium isotherms is illustrated with three widely used expressions for the representation of phosphate sorption by soils but it would also be expected to be useful in connection with sorption of other solutes by soils as well as by other adsorbents.     

Phosphate fixation by bentonite

Introduction

The relative ability of soils, clay minerals, and hydrous oxides to fix phosphorus has been determined by a variety of methods. In order to study phosphate fixation, it is necessary to rigidly control such factors as concentration of phosphorus added, time of reaction, temperature, and pH.     

Differential Growth Response of Wheat Genotypes to Ammonium Phosphate and Rock Phosphate Phosphorus Sources

ABSTRACT

A solution culture experiment was conducted to determine the response of 15 wheat genotypes for growth, phosphorus (P) uptake, and P utilization efficiency, and their adaptability to P stress conditions using adequate [250 μM P in nutrient solution as ammonium phosphate (NH₄H₂PO₄)] and stress (powdered rock phosphate suspended in nutrient solution) P supply levels. Shoot dry matter (SDM) and total plant DM (shoot + root) and P uptake were generally higher for most genotypes in adequate P than stress P level treatment, but the opposite was true for root dry matter (RDM), root: shoot ratio (RSR), and root P uptake. Relative reduction in SDM due to P deficiency stress ranged from none to 54%. Genotypes Kohinoor 83, PB 85, Parvaz 94 and 4770 did not respond to P deficiency stress for SDM production, while genotypes FSD 83, Chakwal 86, Pasban 90, 4072, 4943, 5039, 6529-11, and 6544-6 were highly responsive to P application for SDM. Shoot P uptake in genotypes at adequate P level was about 3-times higher than those genotypes grown at stress P level. Differences in P concentration of shoot ranged between 2.00 to 3.06 mg P g^?1 in stress P level treatment, and had a significant positive correlation with P harvest index (PHI) (r = 0.558?, P < 0.05) and root efficiency ratio (RER) (r = 0.611?, P < 0.05) and negative correlation with P efficiency ratio (PER) (r = ?0.909??, P < 0.01). A significantly positive correlation of P utilization index (PUI) and SDM (r = 0.784??, P < 0.01) and non-significant negative correlation (r = ?0.483) of PUI with P concentration in shoot implies that wheat genotypes with higher PUI may be selected for P deficient milieu. Genotypes with higher PUI (>0.8 g mg^?1 P) in rook phosphate treatment were Inqlab-91, Pak-81, Lu 26s, Parvaz 94, 4072, 4770, 4943, and 5039. There was no interrelationship observed between shoot P uptake and P efficiency in stress P level treatment. However, highly significant and positive correlation (r = 0.720??, P < 0.01) between PHI and RER suggested that shoot P uptake depended upon root efficiency and it increased with the increase in P uptake per unit RDM. Consequently, this resulted in increased SDM which is evident from the significant positive correlation (r = 0.833??, P < 0.01) between SDM and shoot P uptake. In summary, the findings suggest that PUI and RER may be used for selecting P efficient wheat genotypes (e.g., 4072, 4770, 4943, Pak 81, and Inqlab 91) for dry matter production and P use.     

Phosphorus Fractions of Soils Treated with Phosphate Rock and Monocalcium Phosphate after Ryegrass Growth

Abstract

Excess EDDHA (ethylenediamine di(o‐hydroxyphenylacetic acid) ) had little effect on leaf concentrations of Fe in bush beans (Phaseolus vulgaris L. var Improved Tendergreen) when grown in nutrient solution at three pH values from 4.3 to 8.7. An excess of EDDHA 20 times that of Fe decreased yields slightly, but not as result of Fe deficiency. A resulting hypothesis is that chelated Fe can be transferred from chelating agent to uptake sites on roots without going in the ionic form through the solution around roots.     

Phosphate sorption by natural hematites

Iron (hydr)oxides are active phosphate sorbents in soils and sediments, but no information exists on phosphate (P) sorption by natural hematites. In this study, we characterized the chemical, mineralogical and P-sorption properties of 14 hematite-rich natural materials of different origins. Phosphate sorption was described by a modified Freundlich equation including a time term. Phosphate sorbed at 1d at an equilibrium concentration of 1 mg P dm^?3 ranged widely (0.2–1.7 μmol m^?2). After 1 d, hematites showed a marked slow sorption. At 75 d, and an equilibrium concentration of 6mg P dm^?3, the total amount of P sorbed ranged between 0.8 and 4.1 μmol mp^?2. Phosphate-sorption capacity was influenced by the morphology of the coherently scattering domains: the shorter the domains in the crystallographic c relative to the a direction, the lower the P-sorption capacity. This has been observed by other authors in synthetic hematites and agrees with the idea that the prismatic faces, which have singly co-ordinated Fe-OH groups, are more active in P-sorption than other faces. The average P sorption capacity of hematites was similar to that of natural goethites (2.6 μmol P m^?2) but, in contrast to these, variability among samples was high. In comparison with goethites, hematites show slower sorption and lower affinity for phosphate.     

Phosphate fractions in some tanzania soils

Inorganic-P fractions were determined in 17 soil profiles from eight soil orders widely occurring in Tanzania. Most of the inorganic-P fractions decreased with depth. Where soils were young, or calcareous, or the parent material rich in phosphorus-bearing minerals, Ca-P was the dominant inorganic-phosphorus fraction. Where the soils were highly weathered, Al-P and Fe-P were the dominant fractions.     

Phosphate sorption by jurassic oolitic limestones

Sorption isotherms and calcium phosphate solubility data were used to interpret the processes responsible for sorption of phosphate on three Jurassic oolitic limestones whose surface areas ranged from 1.0 to 1.5 m²/g CaCO₃. It was concluded that total sorption was due to (1) an initial chemisorption reaction at final P concentrations below 0.5 μg/ml, with Langmuir adsorption parameters of about k = 10 ml/μg P and x_m = 100 μg P/g; above this concentration most of the additional sorption was due to (2) phisical adsorption (of very low bonding energy) which may occur in multilayers on the initial chemisorbed layer, and (3) precipitation, probably of octacalcium phosphate, Ca₈H₂(PO₄)₆.5H₂O, from solution and its deposition on the adsorbed layers. The last two reactions probably overlap and cannot be distinguished from each other.     

In Situ Acidulation of Rock Phosphate

This study was undertaken to study the impact of adding <75 μm elemental sulfur (ES) on P availability from a range of <250 μm ground rock phosphates (RP) namely; Minjingu (Mi) from Tanzania, Khouribga from Morocco (Mo) and Duchess (D) from Australia. Italian ryegrass (Lolium multiflorum, Thumpa tetraploid) grown in a glasshouse was used as the test crop and tops were harvested 5 times over 27 weeks. Co-granulating RP and 10.7% ES yielded 30–70% more ryegrass tops than RP alone, with the greatest effect with Mi. Fertilizer P recovery in the tops from the RP was 5.2% with D and 6.5% and 7.8% from Mi and Mo, respectively. ES addition increased this by 51% from Mo, 98% from D and 194% from Mi. Co-granulation of RP with ES has been shown to be an effective means of releasing plant available P to crops from RP with minimal fertilizer processing.     

Soil Lead Immobilization Using Phosphate Rock

Phosphate compounds of lead (Pb) are highly insoluble and their formation in contaminated soils would aid immobilization of Pb. The goal of the current research was to evaluate the immobilization of Pb by various treatments of phosphate rock on contaminated agricultural soils typical of Taiwan, and to determine the optimal amount of phosphate rock for use in field application. Samples of contaminated soil, each containing Pb concentrations ranging from 346 to 1873 mg kg^?1 were collected from arable land near a ceramic products manufacturing factory. Both batch immobilization experiments and in situ remediation were completed using phosphate rock additives. Results of the batch experiments demonstrate that the phosphate rock was effective in reducing Pb extractable by 0.1 M HCl, with a minimum reduction of 33–97% after 8 days of reaction, for initial Pb concentrations up to 1873 mg kg^?1. HCl-extractable Pb did not decrease after an additional 2-day reaction with a greater phosphate rock loading. It was also found that the reaction time had less effect on Pb immobilization than the amount of phosphate rock added. Results from in situ remediation experiments indicate that soil-extractable Pb was reduced by 93% (mean; range 85.2–97.2%), which is comparable with the results of the batch study. Additionally, the soil pH was increased from 6.25 (mean; range 5.96–6.76) to 7.2 (mean; range 6.92–7.53) after remediation. Based upon the HCl-extractable Pb content and the amount of phosphate rock added, various linear log-linear regression curves were obtained. These predictive equations have been used for field application. Our field results demonstrate that phosphate rocks have a potential to cost-effectively treat Pb-contaminated soils in Taiwan.     

Ability of Periplasmic Phosphate Binding Proteins from Synechocystis sp. PCC 6803 to Discriminate Phosphate Against Arsenate

Water, Air, & Soil Pollution - Fungus Pleurotus ostreatus Haas can tolerate and remove heavy metals from water. Among three heavy metals tested, the removal of Pb was the most efficient...     

Adsorption of Phosphate on Variable Charge Soils

The study about the adsorption of phosphate on four variable charge soils and some minerals revealed that two stage adsorption appeared in the adsorption isotherms of phosphate on 4 soils and there was a maximum adsorption on Al-oxide-typed surfaces between pH 3.5 to pH 5.5 as suspension pH changed from 2 to 9, but the adsorption amount of phosphate decreased continually as pH rose on Fe-oxide typed surfaces. The adsorption amount of phosphate and the maximum phosphate adsorption pH decreased in the order of yellow-red soil > lateritic red soil > red soil > paddy soil, which was coincided with the content order of amorphous Al oxide. The removement of organic matter and Fe oxide made the maximum phosphate adsorption pH rise from 4.0 to 5.0 and 4.5, respectively. The desorption curves with pH of four soils showed that phosphate desorbed least at pH 5. Generally the desorption was contrary to the adsorption with pH changing.     

Influence of Ectomycorrhizal Hyphae on Phosphate Fractions and Dissolution of Phosphate Rock in Rhizosphere Soils of Pinus radiata

A study was conducted to determine the effect of ectomycorrhizal hyphae on phosphate rock dissolution and soil properties in the rhizosphere of one-year-old Pinus radiata D. Don seedlings established on an allophanic soil (Andosol) in the field. High and low ectomycorrhizal hyphal activities were produced in soils inside the lower compartments of rhizosphere study containers by using either 26 μm or < 10 μ m pore-size nylon mesh(es) at the interfaces between the lower and upper compartments. The meshes at the interfaces allowed (26 μm) or reduced (< 10 μ m) hyphae penetration into the lower compartment. Pairs of containers, one with 26 μ m mesh and the other with < 10 μ m mesh, were buried under Pinus radiata seedlings for 10 months in a forest plantation. The effect of ectomycorrhizal (ECM) hyphal activity on phosphate rock dissolution and soil properties was determined. The increased ECM hyphal activity induced increased soil acidification and promoted greater production of acid phosphatase enzyme, causing greater changes in phosphorus (P) fractions in the rhizosphere soils. The increased ECM hyphal activity also stimulated higher dissolution of phosphate rock and mobilization of soil organic P. The results suggest that ECM hyphal strand has a significant role in mobilizing low-solubility P forms and soil organic P for utilization by the tree.     

磷素在土壤中的扩散规律

本文应用放射性同位素示踪法,研究了黄土区几种土壤中磷素的扩散过程、影响因素以及其对作物有效性的关系。结果表明:1.磷素在土壤中一般仅能扩散3—4cm。10—15天乃基本达到平衡。各种类型土壤的磷素扩散有明显的差别,这与土壤的粘粒含量有关。磷素的扩散系数为7×10^-8-6×10^-7cm²/s;2.土壤水分和厩肥均能明显地增进磷素在土壤中的扩散作用,而无机盐的作用则相反;3.小麦和玉米幼苗从黄绵土中吸收的示踪磷比从红油土中吸     

Agronomic Effectiveness of Partially Acidulated Phosphate Rock

Laboratorial incubation and field experiments were conducted on soils ranging in texture from sandy loam to clay and in pH from 3.6 to 9.0 to determine the agronomic effectiveness of single superphosphate (SSP).fused magnesium phosphate(FMP) and partially acidulated phosphate rock(PAPR) on 8 field crops.The results showed that the pattern of available P released from SSP was fixing-releasing-fixing-steady state,while that of PAPR was shortly fixing-slowly releasing-fixing steady state.And the PAPR,SSP and FMP were equally effective as judged by yield Puptake by phants and extractable P in soils after crop harvesting,The PAPR used as basal fertilizer was more effective than that as top dressing,and its residual effect was also obvious.     

Phosphate reduction in the paddy field I

The paper on the phosphate reduction in the paddy field has not yet been found. Although it seemed that its study was made by a Soviet investigator, K.I. RUDAKOV (2, 3), his research was not concerned with the paddy field and his original paper has not been available to the author.     

Phosphate solubilization potentials of soil Acinetobacter strains

Many phosphate solubilizing microorganisms (PSM) require external pyrroloquinoline quinone (PQQ) for strong phosphorus (P) solubilization in vitro. The objective of this study was to isolate efficient and PQQ-independent PSM. A total of 21 PSM were isolated from the rhizosphere soil of wheat and maize grown in the pots. Acinetobacter strains were the only PQQ-independent and most effective solubilizers of tricalcium phosphate containing agar. The mean P dissolved in liquid cultures of Acinetobacter strains in a 5-day incubation ranged from 167 to 888 μg/ml P. The pH dropped to below 4.7 from 7.8 in six isolates, which produced gluconic acid in concentrations ranging between 27.5 and 37.5 mM. There was a linear regression between soluble P and gluconic acid concentrations in the bacterial cultures (P < 0.05; R ² = 0.59). Inoculation with Acinetobacter sp. WR922 significantly (P < 0.05) increased wheat (Triticum aestivum L.) P content by 27% at 15 days after emergence (DAE) and dry matter by 15% at 30 DAE compared to the control. The plant P content in inoculated plants at 30 DAE was linearly correlated with soluble P of the bacterial cultures (P < 0.05; R ² = 0.69). Gluconic acid production directly affected phosphate solubilization in vitro, which in turn influenced plant P content of inoculated plants in PQQ-independent P-solubilizing Acinetobacter strains.     

小麦季磷肥施用对后作玉米的效果及土壤中无机磷形态转化的影响

在河北衡水潮土上进行田间试验,研究小麦/玉米轮作体系下,小麦季施用磷肥对玉米的后效及土壤中无机磷形态转化的影响。结果表明,与高施磷量(187.5 kg hm-2 P2O5)相比,小麦季磷肥施用量减少20%或40%,甚至当年不施磷,对后作玉米籽粒产量、生物量、植株吸磷量均无明显影响。从玉米苗期到成熟期,土壤中各形态无机磷下降幅度表现为Ca2-P最大,其次是Ca8-P,再次为Al-P。随着施磷量的减少,土壤Olsen-P、Ca2-P含量开始呈现下降趋势。与单施无机磷肥150.0 kg hm-2 P2O5相比,用有机肥猪粪磷替代其中20%无机磷肥,显著提高了土壤Olsen-P、Ca2-P和Ca8-P含量。本文结论认为在高肥力的华北地区小麦/玉米一个轮作周期中,小麦季减少磷肥用量,对后作玉米生长和产量尚未产生明显的影响。适当配施猪粪,减少无机磷肥,可以提高土壤中的Olsen-P和Ca2-P含量,较好地维持玉米季土壤中磷素肥力水平。