The relationship between soil solution pH and Al3+concentrations in a range of South Island (New Zealand) soils

Soil Research ◽  
2000 ◽  
Vol 38 (1) ◽  
pp. 141 ◽  
Author(s):  
M. L. Adams ◽  
D. J. Hawke ◽  
N. H. S. Nilsson ◽  
K. J. Powell

Concentrations of Al3+ were calculated in soil solutions from concentrations of the monomeric ‘reactive Al’ species ([Al3+] + [Al(OH)2+] + [Al(OH)2+] + [AlF2+]) obtained using a recently reported flow injection analysis (FIA) chelating resin technique. Soil solution samples came from 7 sites encompassing a range of New Zealand soils (Brown, Gley, Pallic, Podzol, and Recent Soils) and vegetation types (pasture, shrub lands, and indigenous and exotic forest). Previously published data from a further 7 sites, obtained using a rapid (7 s) FIA technique, were transformed to give compatible results. The resultant data (n = 85) covered the pH range 2.7–7.6, and showed a single curvilinear relationship for log [Al3+] v. soil solution pH, regardless of vegetation or soil type. At pH >5.6, the data had a slope of –2.98 and fell between the amorphous Al(OH)3 and gibbsite solubility lines. At pH <5.0, the data had a slope of –0.46; further, the soil solutions were under-saturated with respect to both minerals. These results are interpreted as indicating control of Al solubility by Al(OH)3 (s) (at pH >5.6) and soil organic matter (at pH <5.0), respectively. This interpretation is supported by data from a pH-dependent Al–fulvic acid binding curve, for which calculated values of [Al3+] follow the same curvilinear relationship determined from the soil solution samples.

Soil Research ◽  
1996 ◽  
Vol 34 (5) ◽  
pp. 769 ◽  
Author(s):  
HJ Percival ◽  
KM Giddens ◽  
R Lee ◽  
JS Whitton

This work investigates the relationship between soil solution aluminium (Al) and extractable Al in some New Zealand soils giving high extractable Al levels, yet with pH(H2O) values ≥ 5.2. Total Al in 1 M KCl extracts ranged from 0.8 to 11.6 cmol(+)/kg, and in corresponding 0.02 M CaCl2 extracts from 0.002 to 0.39 cmol(+)/kg. Soil solutions had low total Al concentrations, ranging from < 0.5 to 12.5 µM, with < 10% of the Al in the monomeric Al form as determined by the chromeazurol S colorimetric method. There was a poor correlation between Al in soil solution and that extracted by either 1 M KCl or 0.02 M CaCl2. The measured monomeric Al concentrations in the soil solutions did not exceed levels corresponding to Al toxicity threshold activities set at 10 or 2 µM, related to a range of pasture plant tolerances, whether based on the activity of Al3+ species alone, or on the sum of the individual activities of Al3+, Al(OH)2+ and Al(OH)2+ species. The high 1 M KCl-extractable and 0.02 M CaCl2-extractable Al values provided a misleading indication of potential Al toxicity status, probably due to the generation of artificially high extracted Al concentrations from these particular types of soils.


2000 ◽  
Vol 80 (2) ◽  
pp. 283-288 ◽  
Author(s):  
Bo Elberling ◽  
Bjarne H. Jakobsen

During soil water extraction, pH can change as a result of atmospheric gas exchange. The pH change is important for monitoring soil acidification and determination of mineralogic controls on the solution composition. As part of a global change programme in Greenland for monitoring long-term changes in Arctic soil solutions we observed that the pH of extracted soil solutions increased in the order of a half pH unit during traditional sampling and handling of the soil solution. CO2 degassing is often considered the most important factor causing such a pH increase. Thus, traditional as well as in-line pH measurements were performed during the summers 1997 and 1998. The in-line method was designed to eliminate atmospheric contact with soil solutions prior to pH measurements. The time-dependent pH error was quantified based on laboratory experiments with soil solution under controlled temperatures and CO2 partial pressures. Equilibrium speciation modelling was used to predict pH values observed in the field and in the laboratory and the model was found to reproduce the observations well. We conclude that traditional pH measurements on extracted soil solutions in the pH range from 5 to 7 are not appropriate for detailed pH measurements due to errors associated with CO2 degassing. In-line measurements provide more accurate measurement necessary for detailed studies on soil acidification dynamics. Key words: pH, carbon dioxide degassing, soil solution, tension lysimeter, arctic soil


2001 ◽  
Vol 34 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Clare O'donnell ◽  
Christine Stephens

In recent years workplace stress has been seen as an important occupational health and safety problem and probation officers in New Zealand have been identified as suffering from increasing perceptions of stress. Accordingly, the present study was undertaken with a sample of 50 New Zealand Probation Officers in three offices to examine the relationship of individual, organisational and work stressors with work related strains. It was predicted that work stressors would be positively related to strains and that individual differences (e.g., age or gender) would have a moderating effect on the relationship between stressors and strains. The results showed that stressors caused by organisational problems, such as role boundary and overload, were related to strains, more strongly than job content problems, such as difficult clients. Secondly, age may have a curvilinear relationship to strains. Thirdly, the office, or place of work, moderates the stressor strain relationship.


Soil Research ◽  
1985 ◽  
Vol 23 (2) ◽  
pp. 151 ◽  
Author(s):  
DC Edmeades ◽  
DM Wheeler ◽  
OE Clinton

In preliminary experiments a centrifuge method for extracting soil solutions was examined. Neither the time nor speed of centrifuging had any effect on the concentrations of cations in soil solution. The concentration of cations increased with decreasing soil moisture content, and NO3, Ca, Mg, and Na concentrations increased with increasing time of storage of freshly collected moist soils. It was concluded that to obtain soil solutions, which accurately reflect the soil solution composition and ionic strength (I) in situ, requires that soil samples are extracted immediately (<24 h) following sampling from the field. Prior equilibration of soil samples, to adjust soil moisture contents, is therefore not valid. The effect of time of sampling and soil type, and the effects of fertilizer and lime applications, on soil solution composition and ionic strength, were measured on freshly collected field moist topsoils. Concentrations of Ca, Mg, K, Na, NH, and NO, were lowest in the winter and highest in the summer. Consequently, there was a marked seasonal variation in ionic strength which ranged from 0.003 to 0.016 mol L-1 (mean, 0.005 s.d. 0.003) over time and soil type. Withholding fertilizer (P, K, S, Ca) for two years had only a minor effect on ionic composition and strength, and liming increased solution Ca, Mg and HCO3, but decreased Al, resulting in a twofold increase in ionic strength. These results suggest that the ionic strength of temperate grassland topsoils in New Zealand lie within the range 0.003-0.016 and are typically 0.005.


Soil Research ◽  
1996 ◽  
Vol 34 (3) ◽  
pp. 369 ◽  
Author(s):  
YP Dang ◽  
KG Tiller ◽  
RC Dalal ◽  
DG Edwards

Soil solutions were obtained by a centrifugation method from 14 unfertilised and fertilised Vertisols. The soil solutions were analysed for all major cations and anions and organic carbon (C). Chemical speciation of zinc (Zn) in the soil solutions calculated with the aid of the computer program GEOCHEM showed that Zn in tile soil solution exists mainly as free Zn2+ ions in these soils. Complexation of total soluble Zn by organic and inorganic ligands constituted 40% and 50%, respectively, of total soluble Zn in fertilised and unfertilised soil solutions. The organo-Zn complexes constituted <10% of the total soluble Zn. The inorganic Zn complexes, ZnHCO3+ and ZnCO3, constituted 60–75% of the total inorganic Zn complexes. The Zn complexes with SO24- and OH- were less than or equal to 5% each of the total inorganic species in unfertilised soils; ZnSOo4 complexes were more common in fertilised soils. The activities of Zn were extremely low (0.01–0.1 µM) in unfertilised soils and were inversely related to soil solution pH. The experimentally determined solubility lines for Zn2+ in the soil solution were undersaturated with respect to the solubility of any known mineral form of Zn. Zn2+ activity was mainly determined by adsorption-desorption reactions. The weak acid ion exchangers, Chelex-100 and Bio Rex-70, retained smaller amounts of Zn front the soil solutions than the strong acid exchangers, AG 50W X2, AG 50W X4, and AG 50w X8. Soil solution pH strongly affected Zn concentrations in soil solutions. The amount of total soluble Zn present as Zn2+ ions as calculated by GEOCHEM was highly correlated with tile amount of soluble Zn retained by the cation exchange resins. In the case of Chelex-100, these amounts were equal, confirming the usefulness of Chelex-100 to estimate Zn2+ ions.


Soil Research ◽  
1999 ◽  
Vol 37 (3) ◽  
pp. 545 ◽  
Author(s):  
A. D. Mitchell ◽  
P. Loganathan ◽  
T. W. Payn ◽  
R. W. Tillman

Magnesium (Mg) deficiency is common in a number of forest regions in the world. It has been linked to a condition in P. radiata called ‘upper mid crown yellowing’ (UMCY) in New Zealand and ‘new type forest decline’ in Europe. Mg concentrations are low in many of New Zealand"s forest soils. With increases in the number of rotations and increased growth rates through tree breeding, Mg deficiency is expected to increase. This study was conducted to determine the fate of calcined magnesite (calmag) fertiliser applied at 150 kg Mg/ha at 2 sites in the Kaingaroa Forest near Rotorua, New Zealand. It also investigated the effectiveness of calmag in increasing the soil solution and soil exchangeable Mg in pumice soils and Mg concentrations in the pine needles, and in reducing the likelihood of UMCY 2 and 3 years after fertiliser application. In both sites and for both years of sampling the application of calmag fertiliser resulted in a significant increase in soil exchangeable and soil solution Mg in the 0–5 cm soil layer. Soil and soil solution pH had also been increased in the top 5 cm soil layer. Two years after application about 90% of the fertiliser applied had dissolved and about 70–80% of the Mg remained in a plant-available form (ammonium acetate exchangeable Mg) in the top 10 cm of soil. Calculations suggest that 3–10% of applied fertiliser had been lost due to leaching. Magnesium fertiliser application also resulted in significant reduction in the exchangeable K: Mg ratio and reduced exchangeable Al in the 0–5 cm soil layer. After 3 years, foliar Mg concentrations increased at all sites in the fertilised trees compared with the control trees, although differences were not yet significant. UMCY severity in the trees was also not significantly affected by the application of Mg fertiliser.


Soil Research ◽  
2003 ◽  
Vol 41 (1) ◽  
pp. 1 ◽  
Author(s):  
H. J. Percival

The disposal of wastewater treatment sewage sludge onto agricultural land in New Zealand has led to the development of guidelines for the upper limit concentrations for total heavy metals in the underlying soil. However, those soil biological and biochemical processes now known to be most sensitive to environmental change are being used internationally to set new soil limits. The soil solution chemistry of a pasture soil amended with heavy metals has been used to assess the bioavailability of several important heavy metals. Field trial plots were treated with both spiked (Cu, Ni, or Zn) and unspiked sewage sludge to raise total soil metal concentrations, both above and below the current New Zealand guideline values. Soils were sampled pre-amendment in 1997 and post-amendment in 1998, 1999, and 2000. Soil solutions were extracted by centrifugation and analysed for pH, for concentrations of heavy metals, major cations and anions, and dissolved organic carbon. Heavy metal speciation was calculated with the GEOCHEM-PC model.Soil solution concentrations of Cu, Ni, and Zn increased with increasing levels of metal in the spiked sludge, reflecting increases in total soil metal concentrations. Cu concentrations changed little with time, but those of Ni and Zn tended to decrease. Cu was much more adsorbed by the soil than was Ni or Zn. The free metal ions, Cu2+, Ni2+, and Zn2+ (representing the most 'bioavailable' fraction), were the dominant metal species in the soil solutions. Variations in free metal ion percentages with metal-spiking level depended on the balance between organic and sulfate complexation for Cu, but on sulfate complexation alone for Ni and Zn. Cu and Ni free metal-ion activities in soil solution were relatively low even at the highest metal loadings in the soil, but may be high enough to cause toxicity problems. Zn activities were very much higher, and at the regulatory limit for zinc likely to affect sensitive biological and biochemical properties of the soil.


Soil Research ◽  
1996 ◽  
Vol 34 (5) ◽  
pp. 735 ◽  
Author(s):  
E Diatloff ◽  
CJ Asher ◽  
FW Smith

Total, exchangeable, and soil solution concentrations were measured for 15 rare earth elements (REEs) in 9 soils from Queensland and New South Wales. In a further 10 acid soils, effects of amendment with CaCO3 or CaSO4 . 2H2O were measured on the concentrations of REEs in soil solution. The total concentration of the REEs in soil solutions from unamended soils ranged from below the detection limit (0.007 µM) to 0.64 µM. Lanthanum (La) and cerium (Ce) were the REEs present in the greatest concentrations, the highest concentrations measured in the diverse suite of soils being 0.13 µM La and 0.51 µM Ce. Rare earth elements with higher atomic numbers were present in very low concentrations. Exchangeable REEs accounted for 0.07 to 12.6% of the total REEs measured in the soils. Addition of CaCO3 increased soil solution pH and decreased REE concentrations in soil solution, whilst CaSO4 . 2H2O decreased soil solution pH and increased the concentrations of REEs in soil solution. Solubility calculations suggest that CePO4 may be the phase controlling the concentration of Ce in soil solution.


Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 67 ◽  
Author(s):  
PL Singleton ◽  
M Mcleod ◽  
HJ Percival

The relationship between Si in soil solution and allophane and halloysite content was studied by using a drainage sequence of three New Zealand soils from rhyolitic volcanic alluvium. Clay mineralogy was compared with soil colour and drainage. Allophane and halloysite contents of two morphologically similar soils from rhyolitic volcanic ash were also studied and possible reasons for differences in mineralogy were determined. Allophane was estimated by acid oxalate and pyrophosphate dissolution. The Al/Si ratio of the allophane was determined and the allophane content of the soil was estimated from the Si extracted in acid-oxalate. Halloysite was estimated by differential thermal analysis of the whole soil. Soil samples were centrifuged with a dense water-immiscible organic liquid to displace the soil solution from between soil particles. The Si in soil solution was then determined by spectrophotometry. Allophane was predominant when Si in soil solution was <10gm-3, and halloysite was predominant when Si in soil solution was >10gm-3. Low Si in soil solution and the presence of allophane was associated with well drained horizons which could be identified by their ochreous colour. High Si in soil solution, the absence of allophane and predominance of halloysite, was associated with poorly drained horizons. These horizons could be identified by their pale colour (chroma <2). In two morphologically similar soils, the change from allophane dominance in one soil to hahoysite dominance in the other soil also corresponded to an increase in Si in soil solution. This was probably the result of slightly slower horizon permeability which increased Si in soil solution to a level favouring halloysite formation.


Soil Research ◽  
1997 ◽  
Vol 35 (1) ◽  
pp. 175 ◽  
Author(s):  
H. K. J. Powell ◽  
D. J. Hawke ◽  
D. Scott

Soil solution samples were taken from 7 plots of varying Hieracium infestation at the AgResearch (NZ) Mt John trial site, Lake Tekapo. The soils, which had been fertilised, oversown, and grazed, were analysed for free (reactive) Al, total Al, pH, NOM (natural organic matter), and phosphate. The plots had received annual fertiliser combinations of 0–100 kg P and 0–20 kg S/ha·year. Soil solution pH was in the range 4·33-5·76 and total Al concentrations were in the range 13–68 µM. Free Al concentrations were in the range 0·48–4·8 µM. The pH dependence of log (free[Al]) (slope: –0·69±0·37) indicated control of soluble Al by NOM rather than Al(OH)3 solubility. Soil solution phosphate concentrations depended strongly on P application rate, reaching over 100 mM. At high P concentrations, the product [Al3+][PO3-4] indicated approximate saturation with respect to variscite. One comparison indicated that effects on pH and NOM in the upper 5 cm were due to the presence or absence of grazing.


Sign in / Sign up

Export Citation Format

Share Document