Inorganic Phosphorus Fractions Research Articles

Nitrogen Fertilization on Uptake of Soil Inorganic Phosphorus Fractions in the Wheat Root Zone

Plant nutrient uptake from the soil is dependent on fertilizers applied, soil chemicals, and other factors. The purpose of this study is to quantify the effects of applied N fertilizers on P uptake by winter wheat (Triticum aestivum L.) and on the change of soil pH in the root zone related to reductions of inorganic P fractions in the rhizosphere soil. An experiment was conducted using different forms of N fertilizers (i.e., NH4+–N and NO3−–N) with three N concentrations (0, 100, and 300 mg kg−1) applied in a calcareous soil. Biomass and total N uptake of the plant increased with the N concentrations and NH4+–N fertilizer resulted in a greater biomass than NO3−–N nutrition. Total P uptake in the plant was also higher with NH4+–N fertilizer than with the NO3−–N nutrition. Compared with the zero N treatment, the soil pH around the roots decreased by 0.30 and 0.65 units, respectively, with N treatments of 100 and 300 mg kg−1 of NH4+–N fertilizer. The amount of soil inorganic P fractions in the root zone decreased with increasing NH4+–N applied. The NO3−–N treatments reduced rhizosphere acidification and had a less impact on the soil inorganic P fractions. The results suggest that enhancing rhizosphere acidification attributable to applications of NH4+–N fertilizer can increase P availability in calcareous soils for plant uptake.

Inorganic and organic phosphorus fractions in peat from drained mires in northern Finland

Soil samples from 15 eutrophic, 26 herb-rich, 15 tall-sedge, and 11 low-sedge drained peatland sites were analysed for easily soluble and aluminum, iron, and calcium bound phosphorus (P) using the Chang and Jackson sequential fractionation method. Compared to earlier investigations, where only total and easily soluble P contents (e.g. NH4OAc or dilute H2SO4 extractable P) in peat have been analysed, significantly higher differences between sites were observed. The eutrophic sites were characterized by four to six-fold greater Ca-bound organic P and two to three-fold greater Ca-bound inorganic P contents than on the other three site type groups, whereas the average Al-bound inorganic P content of the eutrophic sites was only one-third of that at the other site types. Substantial differences between sites were also observed for Fe-bound inorganic P, i.e. two to four-fold greater Fe-P contents were measured at the herb-rich sites compared with the other three site type groups. The stand volume growth in the 67 studied drained peatland sites correlated significantly with Al-bound organic P and Fe-bound inorganic and organic P. The study showed that a detailed fractionation and discrimination of different forms of soil P is important in increasing the understanding of the relationship between P availability and vegetation community types and stand growth on drained peatlands.

Labile Phosphorus in Soils of Forest Fallows and Primary Forest in the Bragantina Region, Brazil

ABSTRACTWe used the Hedley sequential extraction procedure to measure nine different organic inorganic soil phosphorus fractions in forest soil of the Bragantina region of Para, Brazil. We compared the labile fractions (resin‐extractable P + HCO3‐extractable inorganic and organic P) in Oxisols from three secondary forests (10, 20, and 40 years old) and a primary forest. These stands were located in an area that has supported shifting agriculture for approximately a century. After agricultural use, total P and labile P in soils of young secondary forests are diminished compared to the amounts presents in the primary forest soil. Within each stand, organic carbon content was a good predictor of labile organic and inorganic P, consistent with the large body of research indicating that mineralization of organic matter is important to plant nutrition in tropical ecosystems. During the reorganization of P pools during forest development, the pool of labile organic P (HCO3‐extractable) diminishes more than the other labile fractions, suggesting that it is directly or indirectly an important source of P for the regrowing forest vegetation. Across the four age classes of forest, the soil reservoir of labile P was equal to or greater than the total amount of P in the vegetation. If labile P measured by this method adequately represents P available to plants in the short term (as suggested by the current consensus), we would conclude that plant‐available P is reasonable abundant, and that the effects of agriculture on available P pools are detectable but not sufficient to compromise forest regrowth in this area.

Labile Phosphorus in Soils of Forest Fallows and Primary Forest in the Bragantina Region, Brazil1

Abstract We used the Hedley sequential extraction procedure to measure nine different organic and inorganic soil phosphorus fractions in forest soils of the Bragantina region of Para, Brazil. We compared the labile fractions (resin-extractable P + HCO3-extractable inorganic and organic P) in Oxisols from three secondary forests (10, 20, and 40 years old) and a primary forest. These stands were located in an area that has supported shifting agriculture for approximately a century. After agricultural use, total P and labile P in soils of young secondary forests are diminished compared to the amounts present in the primary forest soil. Within each stand, organic carbon content was a good predictor of labile organic and inorganic P, consistent with the large body of research indicating that mineralization of organic matter is important to plant nutrition in tropical ecosystems. During the reorganization of P pools during forest development, the pool of labile organic P (HCO3-extractable) diminishes more than ...

Effect of pine harvesting on leaf nutrient dynamics in young oak trees at NW Spain

The recovering of the native oak forest from pine plantations in unproductive areas is one of the scientific and politic challenges faced in NW Spain. We studied the effect of Pinus pinaster clearcutting on nutrient dynamics and availability for the late-successional species Quercus robur that dominates the understory of the pine canopy. Variations in leaf nutrient content (nitrogen, phosphorus, potassium and sodium) expressed on a leaf mass and area basis, were studied during a growing season, and changes in resorption efficiency, resorption proficiency, nutrient-use efficiency and nutrient-response efficiency were studied in oak leaves of harvested and undisturbed sites. Soil available nitrogen was 30% lower on the harvested sites, but no differences in the inorganic and organic soil phosphorus fractions were detected. Leaf specific mass was significantly higher in trees of the harvested sites, due to the lower leaf area found on these site. Leaf N concentration was 20% higher at the undisturbed sites, but pine harvesting did not modify the leaf P concentration. Consequently, nutrient content in plants seemed to reflect soil nutrient availability. The leaf N-to-P (between 18 and 20) ratio suggested that P was more limiting for growth than N for the young oaks. Pine harvesting increased the resorption rate and resorption efficiency of the young oaks for N, P and K. Pine harvesting decreased by 25% the minimum amount of N and K in the oak leaves (resorption proficiency), but no differences were found in the P resorption proficiency between sites. For P, the resorption proficiency values were nearer to those considered as complete resorption on both sites. Pine harvesting increased the leaf-level nutrient-use efficiency for all nutrients, but decreased the P uptake efficiency on the deforested sites. Our results suggested that changes in nutrient-use efficiency and nutrient resorption of young oaks after pine harvest may be influenced by changes in soil nutrient and light availability caused by pine harvest.

Soil inorganic phosphorus fractions and Olsen-P in phosphorus-responsive calcareous soils: Effects of fertilizer amount and incubation time

Crops grown in calcareous Montana soils with Olsen-P concentrations above critical levels often show responses to phosphorus (P) fertilizers. Objectives of this experiment were to (i) investigate the effects of P fertilization and soil incubation time on soil inorganic P fractions (Pi) and Olsen-P concentrations, and (ii) determine the relationship between each Pi fraction and Olsen-P in P-responsive calcareous soils. Six soils (Ap horizon) were collected from P-responsive locations in Montana based on previous field and greenhouse trials. Each soil was fertilized with 0, 11, 22, and 33 mg P kg− 1-soil and incubated at 20°C for up to 12 weeks. Soils collected after 1, 4, 8, and 12 weeks of incubation were analyzed for Olsen-P, and inorganic P was fractionated into Resin-P, Water-P, NaHCO3-P (bic-P), NaOH-P, and HCl-P. Relative distributions of each Pi fraction followed the order of HCl-P > NaOH-P > Resin-P > bic-P > Water-P, with NaOH-P and HCl-P representing greater than 75% of the total Pi. In general, Resin-P, Water-P, bic-P, their summation (Avail-P), and Olsen-P were significantly correlated with the amount of P added, while NaOH-P and HCl-P were not. Compared to the other Pi fractions, Resin-P was more highly correlated with the amount of P added and increased the most following P fertilization. Olsen-P was significantly correlated with Resin-P at most incubation times, yet, in general, was not significantly correlated with bic-P, NaOH-P, or HCl-P. During the incubation, Resin-P decreased the most of the three available fractions, yet Olsen-P was relatively constant. Combined results suggest that available Pi fractions, especially the Resin-P fraction, may be better indicators than Olsen-P at predicting P availability and P responses in calcareous soils.

Depleção do fósforo inorgânico de diferentes frações provocada pela extração sucessiva com resina em diferentes solos e manejos

O fósforo disponível no solo é equilibrado por formas menos lábeis, as quais, a longo prazo, podem-se tornar potencialmente disponíveis às plantas. O trabalho teve por objetivo (a) avaliar a depleção do fósforo inorgânico de diferentes frações provocada pela extração sucessiva com resina e (b) efetuar um balanço do fósforo no solo. Coletaram-se amostras de solo (Latossolo Vermelho distroférrico típico, Latossolo Vermelho distrófico típico e Argissolo Vermelho distrófico típico), em três camadas (0-2,5, 2,5-7,5 e 7,5-17,5 cm), de quatro experimentos de longa duração, nos sistemas plantio direto e cultivo convencional com diferentes sucessões de culturas. Efetuou-se o fracionamento do fósforo inorgânico pela técnica de Hedley modificada, antes e depois das extrações sucessivas do fósforo com resina em membrana. A fração de fósforo inorgânico extraída com HCl 1,0 mol L-1 foi indisponível, enquanto as frações de fósforo inorgânico extraídas com NaHCO3 0,5 mol L-1 e NaOH 0,1 mol L-1 foram lábeis, independentemente do tipo de solo, método de preparo e sucessão de cultura. Nos Latossolos, a fração de fósforo inorgânico extraída pelo NaOH 0,5 mol L-1 também foi lábil.

PHOSPHORUS DYNAMICS IN A LOWLAND AFRICAN RAINFOREST: THE INFLUENCE OF ECTOMYCORRHIZAL TREES

PHOSPHORUS DYNAMICS IN A LOWLAND AFRICAN RAINFOREST: THE INFLUENCE OF ECTOMYCORRHIZAL TREES

Characterization of organic and inorganic phosphorus in the highland plateau soils of Ethiopia

Abstract Surface horizon samples from two Vertisols, an Andisol, and an Alfisol were collected from farmers’ fields, research station farms, and from uncultivated/ nonfertilized areas to characterize the organic and inorganic forms of phosphorus (P) in the highland plateau soils of Ethiopia using the Hedley soil P fractionation scheme. The total P values ranged from 226 mg‐kg‐1 in the Akaki Vertisol samples developed on alluvial deposits to 1570 mgkg‐1 in the Andisol samples, where the HCl fraction dominates the inorganic soil P pool. The Alfisol samples contained 400 mg‐kg‐1 of total P, with the NaOHand residual P being the dominant P fractions. The resin inorganic phosphorus (Pi) and bicarbonate Pi fractions generally accounted for less than 15% of the total P in all soils, and were positively correlated with organic C. The NaOH P fraction, which was most prominent in the surface horizon samples of the Alfisols, accounted for 4–15% of total P. The HCl P fraction, ranged from 1% in the Alfisols to 46% in the Andisols, and positively correlated with pH. All of the P fractions were negatively correlated with clay and extractable Al contents. The organic P (Po) fractions were positively related to organic carbon (C) and dithionate extractable iron (Fe). All samples collected from farmers’ fields showed a loss of P from the residual, and HCl fractions as compared to the uncultivated/nonfertilized samples. There is also a decrease in the labile P (resin Pi, bicarbonate Pi, and Po) fractions, except for the Akaki Vertisol samples. However, under research station management, the amount of labile P fractions either increased or remained at the same level as the uncultivated/nonfertilized samples, except for the Andisol. Addition of P fertilizer at the recommended rates to the Debre Zeit research station Vertisol appears to have resulted in a slight increase in the labile P and prevented loss of P from the HClP and residual P fractions.

The supply of phosphorus from native, inorganic phosphorus pools in continuously cultivated Mexican agroecosystems

Correlative and experimental approaches were used to determine the sources of phosphorus (P) that supply the labile P pools in nine soils from traditional Mexican agroecosystems. A correlation analysis was undertaken on phosphorus fractions, particle size fractions, soil pH and organic matter contents. Labile inorganic P (labile Pi) fractions correlated significantly with soil HCl-extractable Pi concentrations and soil pH. No significant correlations were found between labile phosphorus and any organic phosphorus pools or particle size fractions. Alfalfa ( Medicago sativa L.) was grown in small quantities of soil and then P fractionations were carried out on the alfalfa-depleted and original soils. Alfalfa consistently depleted labile inorganic phosphorus fractions in all soils, and in five of the nine soils, inorganic phosphorus associated with calcium phosphate minerals and/or Al or Fe hydrous oxides were significantly depleted under cultivation. The bicarbonate extracted organic phosphorus fraction was significantly depleted in one soil, but no other organic phosphorus fractions were significantly depleted by the alfalfa treatment. These results suggest that inorganic P fractions are critical sources of phosphorus in the traditional agroecosystems studied, and that soil calcium phosphate contents may in part determine where continually cultivated agriculture can be sustained without the use of synthetic fertilizers.

Phosphorus model to estimate fractions of inorganic phosphorus in sediments of water bodies

(1993). Phosphorus model to estimate fractions of inorganic phosphorus in sediments of water bodies. SIL Proceedings, 1922-2010: Vol. 25, No. 1, pp. 180-182.

Seasonal variation in organic and inorganic phosphorus fractions of temperate-climate sandy soils

Soils from an arable plot, a grassland plot and pasture plot were sampled over an 18-month period. Inorganic (Pi) and organic (Po) soil phosphorus fractions were extracted sequentially with resin, NaHCO3, and NaOH. Soil solution was sampled on the arable plot and pasture plot during 12 months with teflon suction cups, and the contents of Pi and Po were determined. The patterns of the variation for all soil fractions were similar for the three plots. All soil Pi fractions were at minimum in the cool moist winter period. The soil Po fractions varied less systematically than Pi fractions. The sum of Po fractions had a winter maximum and a spring minimum. For all soil P fractions temporal variation was highly significant (p<0.0001). The magnitude of change in Pi and Po soil fractions was 4–40 times greater than what would be expected from the magnitude of new N mineralization. The content of P in the inorganic soil P fractions was negatively correlated with soil moisture. The variation in organic soil P could not be explained by any single factor, but it is suggested that the variation is caused by changes in solubility rather than by biological transformations. Thus, physicochemical processes masked the impact of biological transformations on the temporal variation of soil phosphorus fractions. Both soil solution Pi and Po varied significantly with time on field scale. In contrast to soil Pi fractions, solution Pi was initially low in the early autumn, increased by a factor 4 during the following 6 weeks, and thereafter decreased to a low level by the end of the sampling period. Soil solution Po had several fluctuations during the sampling period.

The effects of root-induced pH changes on the depletion of inorganic and organic phosphorus in the rhizosphere

A new method allowing control of rhizosphere pH and mineral nutrition was applied to study depletion of various organic and inorganic phosphorus fractions extractable sequentially with 0.5M KHCO3 (pH 8.5), 0.1M NaOH and residual P extractable with 6M H2SO4 from the rhizosphere soil. Soil pH was affected about 2 mm from the root mat. Depletion zones of inorganic P (KHCO3-Pi) extractable with 0.5M KHCO3 extended up to about 4 mm but the depletion zones of all other P fractions were about 1 mm only. The root-induced decrease of soil pH from 6.7 to 5.5 increased the depletion of total P from all fractions by 20% and depletion of KHCO3-Pi and residual P by 34% and 43%, respectively. Depletion of organic P (KHCO3-Po) extractable with 0.5M KHCO3 was not affected by a change in rhizosphere pH. With constant or increased pH, depletion of inorganic P (NaOH-Pi) was 17% and organic P (NaOH-Po) was 22% higher than with decreased pH. Only 54–60% of total P withdrawn from all fractions was from KHCO3-Pi. Substantial amounts of KHCO3-Po and NaOH-Po were mineralized and withdrawn from the rhizosphere within 1 mm from the root mat, as 11–15% of total P withdrawn originated from the organic P fractions. A remaining 11–16% was derived from NaOH-Pi, and 15–18% from residual P fractions likely to be rather immobile. Thus, 40–46% of the P withdrawn near the root mat of rape originated from non-mobile P fractions normally not included in 0.5M NaHCO3 extraction used to obtain an index of plant-available soil P.

Effect of exchangeable calcium on fractionation of inorganic and organic soil phosphorus

Abstract The effects of exchangeable calcium on amounts of inorganic phosphate, organic phosphorus and organic matter extracted from soil by sequential extraction with alkali and acid were investigated. Where exchangeable calcium was present in soil samples, precipitation of calcium phosphate, and calcium‐organic matter complexes occurred during the alkali extraction. Dissolution of precipitated calcium phosphate during subsequent acid extraction caused overestimation of apatite phosphorus in soil and soil/phosphate rock mixtures. Release of exchangeable acidity when exchangeable calcium was removed by prewashing with 1 M NaCl caused dissolution of phosphate rock in freshly prepared soil/rock mixtures. This resulted in underestimation of apatite phosphorus and overestimation of dissolved phosphorus. Buffered NaCl solutions (pH 7.8) were less efficient than unbuffered NaCl at removing exchangeable calcium. However, inclusion of EDTA in the buffered NaCl solution markedly improved the extraction of Ca. Some dissolution of phosphate rock may have occurred during prewashing with buffered NaCl/EDTA solutions. Using EDTA concentrations no greater than that required to complex the exchangeable Ca present in unfertilised soil samples would limit this.

Changes in soil phosphate fractions in the rhizosphere of semi-arid pasture grasses

The comparative ability of several species of grass common to the semi-arid mulga shrublands of south-western Queensland, namely Cenchrus ciliaris cv. U.S.A., Aristida armata, Digitaria ammophilla and Thyridolepis mitchelliana, to deplete various fractions of soil inorganic/organic phosphorus was assessed using a rhizosphere thin section methodology. All species significantly depleted inorganic phosphorus extractable with 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl. The grasses were able to deplete 39, 32, and 29%, respectively, of the inorganic component of each of these extracts. In contrast, the organic phosphorus fraction of all three extracts either remained unchanged or increased in the presence of the grasses compared with unplanted control sections. Depletion of sparingly soluble soil phosphorus coincided with rises in rhizosphere pH. This result contrasts with previous studies that attributed plant depletions of phosphorus pools that are sparingly soluble to an acid hydrolysis process mediated by the root. The liming of the soil had only a minor effect on the distribution of added phosphate between the various soil inorganic phosphorus fractions but resulted in a depletion in the organic fraction of the 0.5 M NaHCO3 and 1.0 M HCl extracts. There was no difference between the grasses in ability to extract the various soil phosphorus pools. These results confirm earlier studies using radioactively labelled compounds of mineral phosphate that these grasses have the ability to utilize sparingly soluble pools of soil phosphorus that are not traditionally considered to be 'plant available'.

The dynamics of different organic and inorganic phosphorus fractions in soils from the south of Santa Fe province, Argentina

Abstract The effect of fractioning organic (Po) and inorganic (Pi) phosphorus components on phosphorus form and availability in long‐term cultivation (1) was studied. The study analyzed a Typic Argiudoll soil under three cropping systems: permanent pasture, long‐term cultivation, and mixed pasture and cultivation use. One soil had been cultivated for at least 50 years and one was cultivated for at least 30 years. The effects of several modifications of these soils were analyzed. Short‐term modifications were determined in a greenhouse experiment in which two successive crops were grown after an initial fertilizer treatment. Long‐term cultivation induced a loss of P, which was considerably greater than the losses of total C or N. Similarly, decreases in pH, extractable P (2), resin‐extractable P, Na‐bicarbonate and Na‐hydroxide Pi, and Na‐bicarbonate Po indicated a long‐term loss of plant‐available Pi with management practices over time. Increases in some forms of P were observed. Sodium‐hydroxide Po, an organic P form, did not show a significant trend but appeared to increase with years of cultivation. Resin‐extractable Pi was the only fraction that increased significantly as a result of P fertilization. The relationship observed between dry weight and P concentration of greenhouse plants with the different organic and inorganic P fractions suggests that both types of determinations may be used to predict crop response to P fertilization.

Prediction of phosphorus fractions in soils

Abstract Organic and inorganic phosphorus fractions were determined in 20 soil samples representing different soil parent materials and cropping managements. The distribution of phosphorus (P) across different fractions and their relationships to soil chemical and physical data were used to develop models capable of predicting P forms. Correlation and multiple regression analyses of P fractions and chemical analyses confirmed that total inorganic P (TIP), occluded inorganic P (OCIP), non‐occluded inorganic P (NOCIP), and Ca‐bound inorganic P (Ca‐BIP) can be relatively accurately predicted from soluble CO2‐ 3 and HCO‐ 3while organic P (OP) can be predicted from soluble CO2‐ 3 and organic matter (OM). Organic matter and electrical conductivity (EC) explained 77% of the variability in the agronmically important P form (loosely bound inorganic P (LBIP)). In general, the predictive models illustrated in this article are useful in estimating P forms from data available in routine soil analysis.

Soil Inorganic Phosphorus Fractions and Their Uptake Relationships in Calcareous Soils

AbstractCrop responses to recommended P‐fertilizer applications are erratic in high pH, calcareous soils of Montana. The objective of this research was to evaluate relationships between soil inorganic P (P1) fractions, Olsen‐P, and plant uptake. Soil‐incubation and plant‐growth experiments were conducted on samples of six calcareous soils from P‐responsive locations in Montana. Rates of P were 0, 11, 22, and 33 mg P kg−1 applied to soils in a randomized complete‐block design with four replications. Spring wheat (Triticum aestivum L. cv. Newana) was grown successively during three, 4‐wk growing periods. Fertilized soils were incubated without plants during the same period. Soils were subjected to a sequential‐fractionation procedure (resin‐P, NaHCO3‐P, NaOH‐P, and HCl‐P). Soil P1 quantities were HCl‐P &gt; NaOH‐P &gt; NaHCO3‐P (bic‐P) &gt; resin‐P. Higher Olsen‐P soils had higher summation of P1 fractions than lower Olsen‐P soils. Changes in resin‐P accounted for most of P1‐fraction differences induced by P application and plant uptake. Cropped soils generally contained lower amounts of P1 in each fraction than noncropped soils. Highly significant (P &gt; 0.01) correlations were found for Olsen‐P vs. resin‐P, P uptake vs. resin‐P, and P uptake vs. Olsen‐P, but not for Olsen‐P vs. bic‐P, resin‐P vs. bic‐P, and P uptake vs. bic‐P. Resin‐P was the best indicator of P‐uptake responses on these soils to P applications and should be considered in the prediction of crop responses.

Effect of cumulative fertilizer dressings on the phosphorus status of mineral soils I Changes in inorganic phosphorus fractions

Surface soil samples were collected from 16 P fertilization trials before onset of the experiments and after seven years of cultivation. The changes in the inorganic P fractions were investigated in plots amended annually with 0, 30 or 60 kg of P ha-1. In the clay soils, cultivation without P fertilization depleted the NH4F-extractable and NaOH-extractable P reserves by 22—69 kg ha-1 ; in the coarser soils, the respective depletion was 8—140 kg ha-1. H2S04-soluble P decreased in seven soils by 16—34 kg ha-1. In the plots amended totally with 210 or 420 kg of P ha-1, on the other hand, these P fractions increased by 24—174 and 46—368 kg ha-1, respectively. The higher the P dressing was, the more the added P tended to accumulate in the fluoride-soluble form as compared to the alkali-soluble form.

Relationship between texture and fractions of inorganic phosphorus in the surface sediment of a reservoir

Inorganic P was fractionated into three categories (NaOH-, BD- and HCI-extractable) for 30 surface sediment samples in La Minilla Reservoir (Sevilla, Spain). The amount of reactive P extracted with NaOH (NaOH-RP) and with HCI (HCI-RP) correlated in a multivariate regression with the clay and sand content of the sediment. This multivariate function should aid in predicting the amount of phosphorus available to the sediment organisms, and it can also contribute to the knowledge of the phosphorus budget of the reservoir.