Soil solution studies on weathered soils from tropical north Queensland

Abstract

Solutions obtained from six soils in tropical North Queensland after incubation at a moisture tension of 0.1 bar were analysed to obtain data on their ionic strengths. Soil extracts, at soil: solution ratios of 1:1, 1:2.5, 1:5, and 1:10 were also examined. Determinations on the aqueous phase included electrical conductivity, pH, ammonium, calcium, magnesium, potassium, sodium, bicarbonate, chloride, sulphate, and nitrate. Ionic concentrations of the soil solutions were found to be low when compared with many of the values reported in the literature. The upper limit for the ionic strength was about 0.005. Ionic strength was well correlated with the electrolytic conductivity of the soil solution itself, and also of the soil extracts. Relationships found between the soil solution and soil extracts in respect of total cation (and anion) content and also cation ratios, allow predictions about the soil solution to be made from soil extract data. Consideration of the ionic ratio of calcium to total cations in these soils suggests that the soils may have suboptimal levels of calcium for the growth of many plant species.

Point of zero charge determination in soils and minerals via traditional methods and detection of electroacoustic mobility

“…This was done to determine the effect of varying I on retention of ions. Ionic strengths of typical non-saline temperate-region soils are < 0.05 M (McBride, 1994), whereas their tropical counterparts are < 0.005 M (Gillman and Bell, 1978). The I values of the two soils used in this study were estimated at 0.003 M each, following the method of Gillman and Bell (1978).…”

Examination of the Distribution of Arsenic in Hydrated and Fresh Cowpea Roots Using Two- and Three-Dimensional Techniques

“…It is known that As(V) is an analog of phosphate and that the addition of phosphate reduces the uptake and toxicity of As(V) (Asher and Reay, 1979). However, the concentration of phosphorus in soil solutions is typically very low; in solutions of unfertilized soils, the phosphorus concentration is typically less than 2 mM (Gillman and Bell, 1978;Menzies and Bell, 1988), and it is generally less than 10 mM even in fertilized soils (Reisenauer, 1966;Kovar and Barber, 1988). Regardless, the presence of phosphate would influence Figure 8.…”

Analysis of Silicon in Soil, Plant and Fertilizer

“…Currently, the chemical extracts reported to be useful in assaying plant-available Si are water (at varying soil: water ratios), sodium acetate buffer (pH 4.0), ammonium acetate (pH 4.8), dilute HCl or H 2 SO 4 , ammonium oxalate (pH 3.0), dilute citric acid or acetic acid, dilute CaCl 2 , dilute phosphate plus acetate (pH 3.5), sodium phosphate buffer (pH 6.2), dilute Na 2 CO 3 , etc. (Gillman and Bell 1978 ;Fox et al 1967 ;Fox and Silva 1978 ;Haysom and Chapman 1975 ;Imaizumi and Yoshidai 1958 ;Haysom and Kingston 2001 ; According to Kilmer ( 1965 ) and Hallmark et al ( 1982 ) 2.4 Analysis of Soluble Silicon in Soil (defi cient) Fox et al ( 1967 ) 40-100 mg kg Korndörfer et al 2001 ;Nayer et al 1977 ;Takahashi 1988 , 1990 ). In general, the most successful extractants are acid rather than neutral or alkaline solutions (Imaizumi and Yoshidai 1958 ), and dissolution is further increased by chelating agents due to decreased Si sorption resulting from the lower concentration of Al and Fe in solution (Berthelsen and Korndörfer 2005 ).…”