Showing 4 results for Chemical Extractants
A. Ghanbari, M. Maftoun, N.a. Karimian,
Volume 3, Issue 4 (1-2000)
Abstract
Different Extractants have been proposed to assess available P in different soils. Olsen method is widely used to determine available P in calcareous soils of Iran. However, it has not been compared adequately with other extractants. The main objective of this experiment was to compare this procedure with some other methods. Thirty nine calcareous soil samples from Fars Province with different physico-chemical characteristics were examined for available P by nine extractants. Furthermore, the effects of four P levels (0, 50, 100, 200 µgPg-1 soil) on growth, P concentration and P uptake by corn were studied in a greenhouse experiment using 20 soil samples. The results indicated that the amount of extractable P decreased in the order, anion-exchange resin > Colwell > Morgan > Olsen > Bray P1 (1:50) > Soltanpour & Schawb > EDTA > Bray P1 (1:7) > Water. The amounts of P extracted by all methods, except that by Bray method, showed significant correlation. However, the correlation coefficients between resin, Olsen, Colwell and water were higher than the others. Regression analysis showed that P extracted by all methods, except Bray, was affected by organic matter and native Zn. Moreover, P removed by Bray method was decreased with an increase in calcium carbonate equivalent. Correlation between top dry weight, relative growth and P uptake and P extracted by resin, Colwell, Olsen and water were highly significant. Although the correlation coefficients between growth parameters and P extracted by Morgan and Soltanpour & Schawb were significant, they were of lower magnitude. Plant phosphorus concentration showed significant correlation with P extracted by Olsen and Colwell methods. In general, resin, Olsen and Colwell methods seem to be appropriate extractants for available P in the present study. However, to select the appropriate extractants, more research is needed.
H. R. Motaghian, A. R. Hosseinpur, F. Raiesi, J. Mohammadi,
Volume 18, Issue 67 (6-2014)
Abstract
Rhizosphere is a small zone and has quite different chemical, physical, and biological properties from bulk soil. This research was performed to study the available Zn and its fractions in the wheat rhizosphere and bulk soils by using rhizobox at greenhouse conditions. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and available Zn using 7 chemical procedures and Zn-fractions were determined in the rhizosphere and bulk soils. The results indicated that TOC, DOC and MBC in the rhizosphere were increased significantly (P<0.01). Zn extracted using several chemical extractants (except 0.01 M CaCl2) in the rhizosphere were significantly (p<0.05) higher than in the bulk soils. Also, concentrations of Zn-fractions (except carbonate-associated) in the rhizosphere were significantly (p<0.05) different from concentrations of Zn-fractions in the bulk soils. Results indicated that correlation between uptake index and extracted Zn using DTPA-TEA and Mehlich 3 were significant (p<0.05). Moreover, significant correlation (p<0.05) between uptake index and exchangeable Zn and Zn associated with iron-manganese in the wheat rhizosphere and bulk soils were found. The results of this research illustrated that available Zn and its fractions in the rhizosphere soils are different from the bulk soils. Therefore, application of the rhizosphere soil would be recommended in the study on these properties after planting.
T. Raiesi, A. Hosseinpur,
Volume 19, Issue 71 (6-2015)
Abstract
The ability of different soil tests in predicting soil phosphorus (P) is important in soils amended with municipal sewage sludge. The objective of the present study was to evaluate several chemical extractants to estimate available P for bean growing in 10 calcareous soils amended with municipal sewage sludge from Chaharmahal-Va-Bakhtiari province under the greenhouse conditions. For this purpose, the soil samples were incubated with sludge at a rate of 39-ton sludge ha–1. The amount of available P of the soil samples was determined by Olsen, Colwell, ammonium bicarbonate-DTPA, 0.01 M calcium chloride, BrayІ, ІІ, Mehlich І and ІІ methods. A pot experiment in a completely randomized design was conducted to evaluate the bean plant indices. The results showed that the amount of extractable P with the above methods decreased in the following order: Colwell> Bray ІІ> Mehlich ІІ> Olsen> Ammonium bicarbonate DTPA> Mehlich І> Bray І> 0.01M chloride calcium. The extractable P with 0.01M chloride calcium, Mehlich І, ІІ Colwell and Olsen methods correlated significantly with plant indices (P concentration and P uptake). Thus, mentioned methods could be used to estimate plant-available P in the soils amended with sewage sludge.
H. Motaghian, M. Shirmohammadi, A. Hosseinpur,
Volume 25, Issue 2 (9-2021)
Abstract
Iron (Fe) is an essential micronutrient for plants and its deficiency occurs in calcareous soils. However, a suitable extractant for the estimation of plant-available Fe and its critical level in calcareous soils depends on the type of soil and plant. The objective of the present study was to evaluate several chemical extractants to estimate available Fe and its critical level for corn growing in calcareous soils from Chaharmahal-Va-Bakhtiari Province. The amount of available Fe was measured by DTPA-TEA, AB-DTPA, 0.01 M calcium chloride, Mehlich IІ, and Mehlich ІІI extractants. At the end of the experiment, corn was harvested, and dry weight, Fe concentration in the plant, and the amount of Fe uptake by corn were determined. Extracted Fe had a significant correlation with all extractants used with maize indices. . The highest correlation coefficients were determined between the DTPA-TEA (0.32-0.94) and AB-DTPA (0.43–0.96) methods and the plant indices. The results of this research showed that the DTPA-TEA and AB-DTPA methods were the most suitable extractants for predicting available Fe content in these soils and the critical level of Fe extracted by these extractants was 2.81 and 3.67 mg kg-1.
