Phosphorus sorption - desorption by purple soils of China in relation to their properties

Soil Research ◽  
2007 ◽  
Vol 45 (3) ◽  
pp. 182 ◽  
Author(s):  
M. Li ◽  
Y. L. Hou ◽  
B. Zhu

The understanding of phosphorus (P) sorption and desorption by soil is important for better managing soil P source and relieving water eutrophication. In this study, sorption–desorption behaviour of P was investigated in purple soils, collected from 3 kinds of purple parent materials with different kinds of land cover, in the upper reaches of Yangtze River, China, using a batch equilibrium technique. Results showed that most of the farmed purple soils had P sorption capacity (PSC) values ranging from 476 to 685 mg P/kg, while higher PSC values were observed in the soils from forestland and paddy field. A single-point P sorption index (PSI) was found to be significantly correlated with PSC (R2 = 0.94, P < 0.001), suggesting its use in estimating PSC across different types of purple soils. The PSC of purple soils was positively and strongly related to the contents of amorphous Fe and Al oxides (r = 0.73, P < 0.001), clay (r = 0.55, P < 0.01), and organic matter (r = 0.50, P < 0.05). Furthermore, the constant relating to binding strength was positively correlated with the content of amorphous Fe and Al oxides (r = 0.66, P < 0.01), but negatively correlated with labile Ca (r = –0.43, P < 0.05) and soil pH (r = –0.53, P < 0.01). Some acidic purple soils with high binding energy featured a power desorption curve, suggesting that P release risk can be accelerated once the P sorbed exceeds a certain threshold. Other soils with low binding energy demonstrated a linear desorption curve. The P desorption percentage was significantly correlated with soil test P (r = 0.78, P < 0.01) and the degree of P saturation (r = 0.82, P < 0.01), but negatively correlated with PSC (r = –0.66, P < 0.01).

Soil Research ◽  
2003 ◽  
Vol 41 (7) ◽  
pp. 1369 ◽  
Author(s):  
M. D. A. Bolland ◽  
D. G. Allen

Soil samples collected from 8 field experiments in Western Australia to which 5–8 amounts of superphosphate had been applied once only 13–23 years previously were used to measure the phosphorus (P) buffer capacity of soil (PBC) and P sorption by several single-point indices. PBC was estimated from well-defined P sorption curves when several levels of P were added to soil suspensions, and was the amount of P sorbed when the concentration of P in the final solution was raised from 0.25 to 0.35 mg P/L. The single-point P sorption indices were measured by adding one amount of P (10 mg P/L) to soil suspensions (1 : 20, soil : 0.02 M KCl or 0.01 M CaCl2). Three indices were calculated from the amount of P sorbed by soil (S, mg P/kg soil) and the amount of P in solution (c, mg P/L)—(1) the phosphorus retention index (PRI, S/c [L/kg]), (2) the Freundlich retention index (FRI, S/c0.35 [dimensionless]), and (3) the phosphorus sorption index (PSI, S/log10 [c × 1000] [dimensionless])—to provide PRI K & Ca, FRI K & Ca, and PSI K & Ca values. P sorption was also measured by the P buffer index (PBI), the new single-point P sorption index recommended for national use, to provide PBICa values. To estimate the previous P sorbed by soil (native soil P is negligible for these soils, so previously sorbed P originates from fertiliser P applied in a previous year), the amount of P extracted by 0.5 M sodium bicarbonate from soil (Colwell soil test P) was added to the amount of P sorbed by soil to calculate PRI*K & Ca, FRI*K & Ca, PSI*K & Ca, and PBI*Ca values. In addition, previously sorbed P was estimated using the q coefficient of the Freundlich equation; q was added to P sorption to calculate PSI**, FRI**, PSI** and PBI** values to take account of previously sorbed P.For the 8 experiments, PBC values significantly decreased where more fertiliser P had been applied to the soils 13–23 years previously. This indicated that the capacity of the 8 soils to sorb P decreased as more P was applied in a previous year, and a single-point P sorption index would need to reflect this decrease. As the amount of P applied to soil in the field plots increased, the following trends occurred : (1) Colwell soil test P always increased; (2) PRIK & Ca, FRIK & Ca, PSIK & Ca, and PBICa consistently decreased; (3) PRI*K & Ca, FRI*K & Ca, PSI*K & Ca, and PBI*Ca mostly increased, but with some values being unaffected or decreasing; (4) PRI**, FRI**, PSI**, and PBI** values were largely unaffected by the amount of P applied in a previous year. Evidently, either adding Colwell soil test P or q to P sorption to calculate the single-point P sorption indices mostly overestimated P sorption by the sandy, low P sorbing soils used, but the overestimate was larger for Colwell soil test P than for q.


2007 ◽  
Vol 87 (5) ◽  
pp. 511-521 ◽  
Author(s):  
Babasola Ajiboye ◽  
Olalekan O Akinremi ◽  
Geza J Racz ◽  
Donald N Flaten

Regulation of manure application in Manitoba has raised the question of whether or not biosolids application should be regulated in the same way. This study examined the effects of biosolids (BIO) applications on P sorption characteristics of a Vertisol in comparison with dairy cattle (DAIRY) and hog (HOG) manures, and monoammonium phosphate (MAP) fertilizer using the classical sorption isotherm and single point sorption index. Pertinent chemical properties and degree of P saturation (DPS) were also determined. The sorption maximum (Smax) in the control was reduced from 655 mg kg-1, to a range of 536–655 mg kg-1 with BIO, 559–650 mg kg-1 with MAP, 402–568 mg kg-1 with DAIRY, and 350–587 mg kg-1 with HOG depending upon the rate of P added. The lower DPS in the soil amended with BIO suggests a lower risk of P loss with biosolids compared with manures. The higher P sorption capacity of biosolids-amended soils compared with soils amended with manures suggest that Ca added with BIO increased the number of P sorption sites by a similar proportion to the amount of P added. Key words: Biosolids, P sorption isotherm, degree of P saturation, labile P, non-labile P


Soil Research ◽  
2008 ◽  
Vol 46 (8) ◽  
pp. 676 ◽  
Author(s):  
L. L. Burkitt ◽  
P. W. G. Sale ◽  
C. J. P. Gourley

Soil phosphorus (P) sorption is an important and relatively stable soil property which dictates the equilibrium between sorbed and solution P. Soil P sorption measures are commonly adjusted for the effect of current P fertility on the amount of P a soil sorbs. In the case of highly fertilised agricultural soils, however, this adjustment is likely to be inappropriate as it may mask changes in a soil’s capacity to sorb P, which could affect future P fertiliser applications. A study was undertaken to compare adjusted or unadjusted methods of measuring P sorption using 9 pasture soils sampled from southern Victoria which had previously received P fertiliser and lime. The P sorption assessment methods included: P sorption isotherms, P-buffering capacity (PBC) measures (slope between equilibrium P concentration of 0.25 and 0.35 mg P/L), and single-point P-buffering indices (PBI), with methods either adjusted or unadjusted for current P fertility. A single application of 280 kg P/ha, 6 months before sampling, resulted in a general negative displacement of unadjusted P sorption isotherm curves, indicating reduced P sorption on 8 of the 9 soils. Adding the Colwell extractable P concentration to the amount of P sorbed before calculating the slope (PBC+ColP), tended to negate this fertiliser effect and, in 2 of the 9 soils, resulted in a significant increase in PBC+ColP values. Increasing rates of P fertiliser application (up to 280 kg P/ha) resulted in a consistent trend to decreasing PBI values (unadjusted for Colwell P), which was significant at 4 of the 9 sites after 6 months. However, only minimal changes in PBI values were determined when PBI was adjusted for current P fertility (PBI+ColP). Phosphorus sorption properties appeared reasonably stable over time, although 2 soils, both Ferrosols, indicated significant linear increases in PBI values when these sites remained unfertilised for 30 months. Lime significantly increased both PBI and PBI+ColP values at all sites 6 months after application, but the effect generally diminished after 30 months, suggesting PBI measurements should not be taken immediately after liming. These results demonstrate that unadjusted measures of P sorption are more likely to accurately reflect changes in soil P sorption capacity following P fertiliser applications and suggest that the unadjusted PBI be used in commercial soil testing rather that the currently adjusted PBI+ColP.


2016 ◽  
Vol 51 (9) ◽  
pp. 1088-1098 ◽  
Author(s):  
Leandro Bortolon ◽  
Paulo Roberto Ernani ◽  
Elisandra Solange Oliveira Bortolon ◽  
Clesio Gianello ◽  
Rodrigo Gabriel Oliveira de Almeida ◽  
...  

Abstract The objective of this work was to assess the risk of phosphorus losses by runoff through an index based on the degree of P saturation (DPS), in cropland soils of Southern Brazil. Sixty-five highly representative cropland soils from the region were evaluated. Three labile P forms were measured (Mehlich-1, Mehlich-3, and ammonium oxalate), and four P sorption indexes were tested (phosphorus single sorption point and Fe+Al determined with the three extractors). Water-extractable P (WEP) was used as an index of P susceptibility to losses by surface runoff. The DPS was determined from the ratio between labile P and each sorption index. DPS values obtained from the ratio between Mehlich-1 P and the single P sorption point ranged from 1 to 25%, whereas those from Mehlich-1 P and Fe+Al (ammonium oxalate) ranged from 1 to 55%. All DPS types were highly correlated with WEP. From a practical stand point, the DPS obtained with both P and Fe+Al extracted with Mehlich-1 can be used to estimate the risk of P losses by runoff in soils of Southern Brazil.


2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Ricardo de Oliveira Munhoz ◽  
Ronaldo Severiano Berton ◽  
Otávio Antonio de Camargo

Land application of biosolids (SS) can cause a buildup of phosphorus (P) in the top soil. The changes in the soil P characteristics may be assessed by the sorption isotherm and the sequential fractionation techniques. Samples of Haplorthox were collected from a field experiment where maize was cultivated for two years, after two applications of SS originated from two cities of São Paulo State, Brazil. SS applications added a total of 125, 250, 500, 1000 and 2000 kg ha−1of P in the area. To perform the sorption isotherms and obtain P maximum sorption capacity (Qmax) and the binding energy, soil samples were submitted to increasing P concentration solutions until equilibrium was reached. Sequential fractionation was done by a sequential extraction with CaCl2, NaHCO3, NaOH, HCl, and HNO3+ HClO4(residual). Addition of biosolids from both cities to the soil decreasedQmaxand the binding energy obtained by the Langmuir equation. SS additions changed the P fractions distribution in the soil by increasing the labile fractions (P-CaCl2and P-NaHCO3) and the moderately labile fraction (P-NaOH) by 11.2% and 20.3%, respectively, in detriment of the most resistant P fraction.


2009 ◽  
Vol 44 (3) ◽  
pp. 243-252 ◽  
Author(s):  
Yang Liu ◽  
Qiang Fu ◽  
Chengqing Yin

Abstract The movement, transformation, and assimilation of phosphorus (P) in a watershed are often related to the physicochemical characteristics of the sediments of the water storage structures in the watershed. Field and laboratory experiments were conducted to study P sorption by pond sediments in a multipond system in a watershed of 6.9 km2 in southeastern China. Being scattered in different ambient land uses, and receiving soil particles from various sources, the multipond system provides an excellent research example for P sorption as well as the relationship between pond properties and their location in a watershed. It was found that the pond sediments showed largely variable P sorption capacities in this watershed. The P sorption maximum (Smax) ranged from 390.0 to 729.2 mg/kg, and equilibrium P concentration (EPC0) ranged from 0.007 to 0.023 mg/L. The mean degree of P saturation (DPS) of the pond sediments was only 9.5%. Due to the large annual delivery of sediments to the ponds by soil erosion, the pond sediments never reached saturation. The location of the ponds could influence the physicochemical properties of sediments and their sorption characteristics. For Smax, the Hill pond value was significantly higher than that for the Village pond. For EPC0, the result was reverse. The oxalate-extractable Fe (Ox-Fe) and KCl-extractable P (KCl-P) were the key factors that influenced P sorption of the pond sediments. Ox-Fe could explain 84% of the variability in Smax and KCl-P could explain 82% of the variability in EPC0. The acidic and high Fe contents of laterite soil in southeastern China was the most important cause of the high P sorption capacity of the pond sediments.


Soil Research ◽  
2007 ◽  
Vol 45 (4) ◽  
pp. 262 ◽  
Author(s):  
M. D. A. Bolland ◽  
D. P. Windsor

The recently developed phosphorus (P) buffering index (PBI) is now the national single-point P sorption index to rank the capacity of soil to sorb P. However, before PBI was developed, P sorption was routinely measured by 2 simple procedures in Western Australia: (i) since the mid 1970s, reactive iron (Fe), which is the concentration of Fe extracted from soil by ammonium oxalate; and (ii) since the mid 1980s, the P retention index (PRI), a single-point P sorption index. Both reactive Fe and aluminium (Al) extracted from soil by ammonium oxalalate (reactive Al) have been measured in experiments conducted in Western Australia. Because PBI is now routinely measured in Western Australia there is the need to convert historical reactive Fe, reactive Al, and PRI values to PBI values. In this study we used soil samples collected from 2 field studies and a study of 96 paddocks, all on sandy soil types common in the region, to measure PBI, reactive Fe, reactive Al (not measured in the paddock study), and PRI. We related PBI (dimensionless), as the dependent (y-axis), to reactive Fe (mg/kg), reactive Al (mg/kg), or PRI (mL/g), as the independent (x-axis). The relationships for all data were good for reactive Al (47 data points from the 2 field studies) and PRI (133 data points for the 2 field studies and the paddock study): --> However, the relationships was poor for reactive Fe (133 data points) and differed for each of the 2 field studies and the paddock study, so no consistent, reliable approach for converting reactive Fe to PBI values could be determined. We recommend that reactive Fe is no longer used in the region, and that only PBI is used to estimate P sorption.


2016 ◽  
Vol 96 (3) ◽  
pp. 289-298 ◽  
Author(s):  
Yongzhuang Wang ◽  
Joann K. Whalen ◽  
Xin Chen ◽  
Yanhong Cao ◽  
Bin Huang ◽  
...  

Exudation of low-molecular-weight organic acids (LMWOAs) from plant roots enhances phosphorus (P) acquisition from soil, either by dissolving P fixed in secondary minerals or by reducing P sorption to organo-minerals. How LMWOAs may modify P sorption in soils with contrasting pH is not well understood, much less the mechanisms involved. The effects of three common LMWOAs (oxalic, citric, and malic acids) on P sorption in calcareous, neutral, and acidic soils were studied in batch experiments, followed by sequential P fractionation to elucidate the mechanisms whereby LMWOAs alter P sorption. The sorption data of the three soils fitted better to the Freundlich equation (r2 = 0.325–0.994, P < 0.05) than the Langmuir and linear equations. Oxalic, citric, and malic acids at 10 mmol kg−1 soil decreased the Freundlich P sorption parameters Kf and n, which represent P sorption capacity and energy, due to the fact that LMWOAs reduced P sorption in NaHCO3-Pi (soil soluble and exchangeable Pi, 23.8–30.9%) and NaOH-Pi (Fe-Pi and Al-Pi, 21.6–54.2%) fractions of the three soils. Comparing acidified P-LMWOAs solutions with the pH-adjusted P-LMWOAs solutions (pH = 7) had a minor effect on P sorption. Our results indicated that the reduction in soil P sorption was due to ligand exchange and chelation of LMWOAs with Fe and Al minerals, and the acid strength of LMWOAs had a minor effect on P sorption in calcareous, neutral, and acid soils.


Soil Research ◽  
2019 ◽  
Vol 57 (1) ◽  
pp. 17 ◽  
Author(s):  
Julia Brenner ◽  
Wesley Porter ◽  
Jana R. Phillips ◽  
Joanne Childs ◽  
Xiaojuan Yang ◽  
...  

Phosphorus (P) availability critically limits the productivity of tropical forests growing on highly weathered, low-P soils. Although efforts to incorporate P into Earth system models (ESMs) provide an opportunity to better estimate tropical forest response to climate change, P sorption dynamics and controls on soil P availability are not well constrained. Here, we measured P and dissolved organic carbon (DOC) sorption isotherms on 23 soils from tropical Oxisol, Ultisol, Inceptisol, Andisol, and Aridisol soils using P concentrations from 10 to 500mg P L−1, and DOC concentrations from 10 to 100mg DOC L−1. Isotherms were fit to the Langmuir equation and parameters were related to soil characteristics. Maximum P sorption capacity (Qmax) was significantly correlated with clay content (ρ=0.658) and aluminium (Al)- or iron (Fe)-oxide concentrations (ρ=0.470 and 0.461 respectively), and the DOC Qmax was correlated with Fe oxides (ρ=0.491). Readily available soil characteristics could eventually be used to estimate Qmax values. Analysis of literature values demonstrated that the maximum initial P concentration added to soils had a significant impact on the resultant Qmax, suggesting that an insufficiently low initial P range could underestimate Qmax. This study improves methods for measuring P Qmax and estimating Qmax in the absence of isotherm analyses and provides key data for use in ESMs.


2019 ◽  
Vol 65 (No. 2) ◽  
pp. 78-82 ◽  
Author(s):  
Ewa Szara ◽  
Tomasz Sosulski ◽  
Magdalena Szymańska

The study aimed at the evaluation of the accumulation and vertical distribution of different forms of phosphorus (P) in reference to phosphorus sorption properties subject to mineral (NPK), mineral-organic (NPK + M), and organic (M) fertilisation. It was carried out in a long-term experimental field in Skierniewice (Central Poland) conducted since 1923 under rye monoculture. Total P content in the M and NPK soil profile was similar and lower than in the NPK + M soil. The content of organic P in A<sub>p</sub> and E<sub>et</sub> horizons of both manured soils was similar and higher than in the NPK soil. The Langmuir P sorption maximum (S<sub>max</sub>) in the studied soils ranged from 39.7 to 90 mg P/kg, while the Freundlich P sorption coefficient a<sub>F</sub> ranged from 6.9 to 41.9 mg P/kg. Higher variability of parameters related to the binding energy from the Lanqmuir (k) and Freundlich (a<sub>F</sub>) equations was determined between soil horizons than between the fertilisation systems. Nonetheless, in M and NPK + M soils, sorption parameters a<sub>F</sub> and S<sub>max</sub> and binding energy (k, b<sub>F</sub>) were considerably lower than in the NPK soil. The content of water extracted P in manured soils was higher than in the NPK soil.


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