Copper release kinetics: Effect of two extractants and wheat (Triticum aestivum L.) rhizosphere

Abstract

The greenhouse experiment was performed to determine Cu release characteristics in the bulk and the rhizosphere of some calcareous soils using rhizobox. The kinetics of Cu release in the bulk and the rhizosphere soils were determined by successive extraction with diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA) and 10 mmol/L citric acid in a period of 1 to 504 h at 25 ± 1°C. The results of kinetics study showed that Cu extracted using DTPA-TEA in the rhizosphere soils was significantly (P < 0.01) lower than the bulk soils, while Cu extracted using citric acid in the rhizosphere soils was significantly (P < 0.01) higher than the bulk soils. The mean of released Cu after 504 h using DTPA-TEA were 8.59 and 7.46 mg/kg in the bulk and the rhizosphere soils, respectively. The mean release of Cu after 504 h using citric acid was 14.73 and 16.05 mg/kg in the bulk and the rhizosphere soils, respectively. Release kinetics of Cu in two extractants conformed fairly well to parabolic diffusion, power function, and first order equations. The results of correlation analysis illustrated that a significant correlation between Cu desorption after 504 h with citric acid and Cu concentration in wheat was found (r = 0.96 and r = 0.90 in the rhizosphere and the bulk soils, respectively, P < 0.01). Therefore, application of 10 mmol/L citric acid extractant would be recommended in the future study on the kinetics of release of Cu in calcareous soils.

Effect of Bean (Phaseolus vulgarisL.) Rhizosphere on Zinc-Release Kinetics

“…In addition, the different chemical and biological conditions of the rhizosphere with respect to the bulk soil can affect Zn fractions and therefore its availability (Wang et al 2002;Motaghian and Hosseinpur 2012).…”

“…A little information about the effect of rhizosphere on release of Zn is available (Motaghian and Hosseinpur 2012). Therefore, the objectives of the present study were (i) to evaluate the Zn release from bulk and bean rhizosphere soils, (ii) to evaluate different mathematical models for describing Zn release, and (iii) to evaluate relation between Zn release characteristics and Zn extracted by using 3 extraction methods in the bulk and the rhizosphere soils.…”

“…A homemade rhizobox (Figure 1)(Wang et al 2002;Motaghian and Hosseinpur 2012) was used to plant bean (Phaseolus vulgaris L.). The dimension of the rhizobox was 200mm × 130mm × 200mm (length × width × height).…”