Soil phosphorus: its measurement, and its uptake by plants

Soil Research ◽  
1997 ◽  
Vol 35 (2) ◽  
pp. 227 ◽  
Author(s):  
I. C. R. Holford
Keyword(s):  
Soil Solution ◽  
Small Proportion ◽  
Plant Uptake ◽  
Solid Phase ◽  
Calcareous Soils ◽  
Buffering Capacity ◽  
Available P ◽  
P Availability ◽  
The World ◽  
Labile P

Phosphorus (P) is the most important nutrient element (after nitrogen) limiting agricultural production in most regions of the world. It is extremely chemically reactive, and more than 170 phosphate minerals have been identified. In all its natural forms, including organic forms, P is very stable or insoluble, and only a very small proportion exists in the soil solution at any one time. Plant-available P may be considered in either its quantitative or intensive dimension. The quantity of available P is time-specific and crop-specific, because it is the amount of P that will come into the soil solution and be taken up by the crop during its life cycle. The intensity of available P (availability) is most easily identified with its concentration in the soil solution. The soil property controlling the relationship between the solid phase P and its concentration in solution is known as the buffering capacity. The solid phase P involved in this relationship is only a small proportion of the total P, and is known as labile P. It is usually measured by isotopic exchange, but this exchangeable P component does not include the sparingly soluble compounds that also replenish the soil solution as its concentration is depleted by plant uptake. The buffering capacity is the ability of the soil solution to resist a change in its P concentration as P is removed by plant uptake or added in fertilisers or organic materials. Buffering capacity is synonymous with sorptivity, which is a preferable term in the context of the reactivity of P fertiliser with soil. It is usually measured from an adsorption isotherm. By fitting a suitable equation, such as the Langmuir, the total sorption capacity as well as the sorption strength can be determined. Both parameters are important in understanding P availability in soils. Buffering capacity has a major effect on the uptake of labile P because it is inversely related to the ease of desorption of solid phase P and its diffusion. Available P therefore is a direct function of the quantity of labile P and an inverse function of buffering capacity. This has been demonstrated in plant uptake studies. Similarly, the most effective methods of measuring available P (soil tests) are those which remove a proportion of labile P that is inversely related to buffer capacity. Soil tests which measure the concentration of P in solution actually measure availability rather than available P, and their efficacy on a range of soils will depend on the uniformity of the soils" buffer capacities. The most effective soil test usually consists of an anionic extractant. Acidic lactate or fluoride have been found most effective in New South Wales, on a wide range of soils, except calcareous soils which neutralise the acidic component (usually hydrochloric or acetic acid) of the extractant. Sodium bicarbonate (pH 8 · 5) has been found effective on calcareous soils and is widely used throughout the world. It has proved unreliable on NSW soils, and may need more thorough evaluation on non-calcareous soils in other parts of Australia.

scholarly journals Phosphorus availability in a low pH highly weathered soil as affected by added salts

1995 ◽  
Vol 25 (2) ◽  
pp. 219-222 ◽  
Author(s):  
Paulo Roberto Ernani ◽  
Stanley Arthur Barber
Keyword(s):  
Soil Solution ◽  
Soil Property ◽  
Solid Phase ◽  
Low Ph ◽  
Soil Samples ◽  
P Availability ◽  
Soil P ◽  
Weathered Soil ◽  
Sulfate Salts ◽  
Soil Chloride

Concentration and identity of cations and anions in the soil solution may affect soil P reactions and thus P availability. The magnitude of these reactions was evaluated in this research after application of various salts to a highly weathered low pH soil. Chloride, nitrate, and sulfate salts of Na, NH4, K, Ca, Mg, Sr, or Cu were added to the soil after addition of 360mg P/kg trying to simulate ion concentrations around granules of fertilizers in the soil. Thirty days later, P was determined in the soil solution (Pli) and on the solid phase (Psi). The soil samples of some treatments were leached with water and three days later a new soil solution was displaced. Separate addition of all salts increased Pli, except NaCl at the lowest rate. The increase of Pli was highly associatcd with amount of native cations displaced to the soil solution by the applied salts. Salt solubility, concentration, and sometimes identity of cation and anion also influenced Pli. Some salts decreased Psi, but this was not correlated with any soil property measured. The effects caused by salts on Pli and Psi disappeared after leaching the soil samples.

scholarly journals Synchronous Cycle of Available Phosphorus, Iron, and Sulfur in the Sediment of Lancang River Reservoirs

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2691
Author(s):  
Zheng Mu ◽  
Yao Cheng ◽  
Qiang Huang ◽  
Mingming Hu ◽  
Wei Dong ◽  
...  
Keyword(s):  
Large Scale ◽  
Solid Phase ◽  
Available P ◽  
Release Mechanism ◽  
Available Phosphorus ◽  
Lancang River ◽  
Significant Difference ◽  
Phosphorus Iron ◽  
Deep Reservoir ◽  
Labile P

Large-scale deep reservoirs associated with hydropower cascade development are known to influence the cycle of phosphorus (P). However, there is scarce information on the fractions and availability of P in sediments of large-scale deep reservoirs constructed due to hydropower cascade development. In this study, we researched the fractions and release mechanism of P in the sediments of large-scale deep reservoirs by analyzing the fractions and availability of P in the sediments of the Xiaowan (XW) and Nuozhadu (NZD) reservoirs in the middle and lower reaches of the Lancang River (China). According to the results, there is a significant difference in the P fractions in the sediments of the XW and NZD reservoirs, but not for the available P in the sediments. Compared to the NZD reservoir, there was less solid bioavailable phosphorus (BAP) in the sediments of the XW reservoir, but the replenishment degree of active solid phase P into pore water was higher in the XW. There was a significant positive correlation between the available P and the BAP; the Fe/P ratio measured by the diffusive gradients in thin films reflects the control of active iron (oxyhydr) oxides over labile P in the sediments. In addition to the reductive dissolution of iron-bound P, the release of P into the large deep reservoirs may be related to factors such as the sulfate reduction and the degradation of organic materials. The P cycling in deep reservoir sediments is mainly controlled by the Fe, and there is a clear spatial distribution of this mechanism in deep reservoirs.

scholarly journals Preface to 'Role of Reactive Phosphate Rock Fertilisers for Pastures in Australia'

1997 ◽  
Vol 37 (8) ◽  
pp. I
Author(s):  
Peter W. G. Sale
Keyword(s):  
Phosphate Rock ◽  
Laboratory Finding ◽  
Relative Effectiveness ◽  
Buffering Capacity ◽  
Available P ◽  
P Availability ◽  
Surface Soils ◽  
Agronomic Effectiveness ◽  
Pasture Production ◽  
P Buffering Capacity

Summary. The dissolution of North Carolina phosphate rock (NCPR) in soil was investigated in a laboratory study using surface soils sampled from 28 permanent pasture sites. The relationships between phosphorus (P) dissolved, P availability and various soil properties were investigated using simple and multiple linear regression and the findings related to the relative effectiveness of NCPR for pasture production at the sites. The extent of dissolution of NCPR was positively correlated to P buffering capacity (r2 = 0.42). Phosphorus buffering capacity and titratable acidity together accounted for 72% of the variance in dissolution. Bicarbonate-extractable P (‘available’ P) generally increased as dissolution increased. However, the increase in available P was consistently lower for soils with higher P buffering capacity. The proportion of dissolved P that was available also decreased with increasing P buffering capacity (r2 = 0.63). Consequently, the increase in available P was highest for soils with very low to low P buffering capacity. This suggests that the effectiveness of NCPR as a fertiliser may be more closely related to the availability of dissolved P, than to the amount of NCPR dissolved in a soil. Consistent with this laboratory finding, the agronomic effectiveness of NCPR relative to superphosphate measured in the field tended to decrease with increasing P buffering capacity. The agronomic effectiveness of NCPR was comparable with superphosphate only at certain sites, and with some noted exceptions, most of these had surface soils with very low to low P buffering capacity. The high relative effectiveness of NCPR at these sites was mostly attributed to the loss of superphosphate by leaching. Since NCPR dissolves much more slowly than superphosphate, only a small amount of the P applied as NCPR would be lost during leaching events. Slow dissolution of the remaining NCPR probably supplied a small amount of dissolved P over an extended period of time, and due to the low P buffering capacity, much of this was available to plants.

Chemical characteristics of phosphorus in alkaline soils from southern Australia

Soil Research ◽  
2003 ◽  
Vol 41 (1) ◽  
pp. 61 ◽  
Author(s):  
I. Bertrand ◽  
R. E. Holloway ◽  
R. D. Armstrong ◽  
M. J. McLaughlin
Keyword(s):  
Calcareous Soils ◽  
The Other ◽  
P Availability ◽  
Alkaline Soils ◽  
Sorption Behaviour ◽  
P Sorption ◽  
Extractable P ◽  
Caco3 Content ◽  
Labile P ◽  
Western Victoria

This study was performed to better understand the chemical behaviour of P in a variety of alkaline soils from southern Australia. To do so, surface soil samples of 47 alkaline cropping soils from Upper Eyre Peninsula in South Australia and from western Victoria were collected. The 22 soils collected from Eyre Peninsula were Calcarosols, and those from western Victoria were Vertosols, Alkaline Duplex soils, Sodosols, and Red Brown Calcareous soils. Parameters included total and amorphous Al and Fe, organic C, organic P, CaCO3 content, P sorption characteristics, phosphorus buffer capacity, calcium lactate (Ca-Lac) extractable P, bicarbonate-extractable (Colwell) P, water-extractable P, anion exchange membrane extractable P (AEM-P), and isotopically exchangeable P (labile P). Concentrations of micronutrients in the Calcarosols were relatively low, considered to be a function of low clay contents. Given very low background Cd concentrations in the soils, it was estimated from Cd measurements that the majority of total P in the soils was derived from previous fertiliser applications. Phosphorus buffer capacities (PBCs) were relatively high in the Calcarosols and moderately high in the other alkaline soils. P sorption behaviour in the Calcarosols was a direct function of CaCO3 content, although in the other alkaline soils, amorphous Al and Fe oxides were the principal determinants of the P sorption behaviour. Both Colwell and Ca-Lac extractants dissolved non-labile P in the highly calcareous soils, whereas AEM appeared to only remove surface-adsorbed P. In addition, Colwell P values were positively related to PBC and to the slope term in the Freundlich model (Kf) when Kf > 10. It is suggested that AEM-P may be a better predictor of P availability in highly calcareous soils compared with the other extractants.

scholarly journals Could biochar amendment be a tool to improve soil availability and plant uptake of phosphorus? A meta-analysis of published experiments

2021 ◽  
Author(s):  
Fitsum Tesfaye ◽  
Xiaoyu Liu ◽  
Jufeng Zheng ◽  
Kun Cheng ◽  
Rongjun Bian ◽  
...  
Keyword(s):  
Plant Uptake ◽  
P Uptake ◽  
Available P ◽  
Soil Conditions ◽  
P Availability ◽  
Vegetable Crops ◽  
Soil P ◽  
Plant P Uptake ◽  
Soil Available P ◽  
Biochar Amendment

AbstractAs one of the most important nutrients for plant growth, phosphorus was often poorly available in soil. While biochar addition induced improvement of soil structure, nutrient and water retention as well as microbial activity had been well known, and the effect of biochar soil amendment (BSA) on soil phosphorus availability and plant P uptake had been not yet quantitatively assessed. In a review study, data were retrieved from 354 peer-reviewed research articles on soil available P content and P uptake under BSA published by February 2019. Then a database was established of 516 data pairs from 86 studies with and without BSA in agricultural soils. Subsequently, the effect size of biochar application was quantified relative to no application and assessed in terms of biochar conditions, soil conditions, as well as experiment conditions. In grand mean, there was a significant and great effect of BSA on soil available P and plant P uptake by 65% and 55%, respectively. The effects were generally significant under manure biochar, biochar pyrolyzed under 300 °C, soil pH <5 and fine-textured soil, and soils that are very low in available P. Being significantly correlated to soil P availability (R2=0.29), plant P uptake was mostly enhanced with vegetable crops of high biomass yield. Overall, biochar amendment at a dosage up to 10 t ha−1 could be a tool to enhance soil availability and plant uptake of phosphorus, particularly in acid, heavy textured P-poor soils.

scholarly journals Phosphorus extracted by ion exchange resins and mehlich-1 from oxisols (latosols) treated with different phosphorus rates and sources for varied soil-source contact periods

2013 ◽  
Vol 37 (3) ◽  
pp. 667-677 ◽  
Author(s):  
Irio Fernando de Freitas ◽  
Roberto Ferreira Novais ◽  
Ecila Mercês de Albuquerque Villani ◽  
Sarah Vieira Novais
Keyword(s):  
Sandy Loam ◽  
Extraction Methods ◽  
Available P ◽  
Molar Ratio ◽  
P Availability ◽  
Triple Superphosphate ◽  
Experimental Conditions ◽  
Reactive Phosphate ◽  
Exchange Resins ◽  
P Sources

Despite the large number of studies addressing the quantification of phosphorus (P) availability by different extraction methods, many questions remain unanswered. The aim of this paper was to compare the effectiveness of the extractors Mehlich-1, Anionic Resin (AR) and Mixed Resin (MR), to determine the availability of P under different experimental conditions. The laboratory study was arranged in randomized blocks in a [(3 x 3 x 2) + 3] x 4 factorial design, with four replications, testing the response of three soils with different texture: a very clayey Red Latosol (LV), a sandy clay loam Red Yellow Latosol (LVA), and a sandy loam Yellow Latosol (LA), to three sources (triple superphosphate, reactive phosphate rock from Gafsa-Tunisia; and natural phosphate from Araxá-Minas Gerais) at two P rates (75 and 150 mg dm-3), plus three control treatments (each soil without P application) after four contact periods (15, 30, 60, and 120 days) of the P sources with soil. The soil acidity of LV and LVA was adjusted by raising base saturation to 60 % with the application of CaCO3 and MgCO3 at a 4:1 molar ratio (LA required no correction). These samples were maintained at field moisture capacity for 30 days. After the contact periods, the samples were collected to quantify the available P concentrations by the three extractants. In general, all three indicated that the available P-content in soils was reduced after longer contact periods with the P sources. Of the three sources, this reduction was most pronounced for triple superphosphate, intermediate for reactive phosphate, while Araxá phosphate was least sensitive to the effect of time. It was observed that AR extracted lower P levels from all three soils when the sources were phosphate rocks, while MR extracted values close to Mehlich-1 in LV (clay) and LVA (medium texture) for reactive phosphate. For Araxá phosphate, much higher P values were determined by Mehlich-1 than by the resins, because of the acidity of the extractor. For triple superphosphate, both resins extracted higher P levels than Mehlich-1, due to the consumption of this extractor, particularly when used for LV and LVA.

scholarly journals Szerb hadifoglyok Bihar vármegyében, 1914–1920

2020 ◽  
Vol 32 (2) ◽  
pp. 22-41
Author(s):  
Oszkár Gorcsa
Keyword(s):  
Everyday Life ◽  
20Th Century ◽  
Small Proportion ◽  
Point Of View ◽  
General Treatment ◽  
World War ◽  
The People ◽  
The Everyday ◽  
The World ◽  
The Great War

The World War can be justifiably called the great seminal catastrophe of the 20th century, because the war that should have ended every further war, just disseminated the seeds of another cataclysm. From this point of view it is comprehensible why lots of historians deal with the named period. Numerous monographies and articles that deal with the destructing and stimulating eff ect of the Great War have seen the light of day. However, the mentioned works usually have serious defi cenceis, as most of them deal only with the battlefi elds, and a small proportion deals with the question of everyday life and hinterland, and the ordeals of the POWs are superfi cially described. In case of Hungary, the more serious researches related to POWs only started at the time of the centenary. This is why we can still read in some Serbian literatures about the people annihilating endeavors of the „huns” of Austria–Hungary. My choice of subject was therefore justified by the reasons outlined above. In my presentation I expound on briefly introducing the situations in the austro–hungarian POW camps. Furthermore, the presentation depicts in detail the everyday life, the medical and general treatment, clothing supply, the question of the minimal wages and working time of the prisoner labour forces. Lastly, I am depicting the problem of escapes and issues dealing POWs marriage and citizenship requests.

scholarly journals Downward Movement of Potentially Toxic Elements in Biosolids Amended Soils

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Silvana Irene Torri ◽  
Rodrigo Studart Corrêa
Keyword(s):  
Groundwater Contamination ◽  
Soil Solution ◽  
Soil Profile ◽  
Toxic Elements ◽  
Solid Phase ◽  
Land Application ◽  
Potentially Toxic Elements ◽  
Downward Movement ◽  
Amended Soils

Potentially toxic elements (PTEs) in soils are mainly associated with the solid phase, bound to the surface of solid components, or precipitated as minerals. For most PTEs, only a small portion is dissolved in the soil solution. However, there is an interest in following the fate of mobile PTEs in the environment, for a growing amount of evidence indicates that downward movement of PTEs may occur in biosolids amended soils, leading to groundwater contamination. Therefore, it is crucial to understand the factors that control the release of these elements after land application of biosolids, in order to overcome problems related to downward movement of PTEs in the soil profile.

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