اثر فرا ریشه لوبیا قرمز (Phaseolus vulgaris L.) بر قابلیت استفاده و شکلهای مس در تعدادی از خاکهای آهکی ایران

Abstract

Change in microorganism activity and chemical properties can be affect on availability and fractionation of Copper (Cu). This research was conducted to investigate the availability and fractionation of Cu in the bean rhizosphere and bulk soils in 10 calcareous soils using rhizobox at greenhouse. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), pH, available Cu (by using 7 chemical extractants) and Cu-fractions were determined in the rhizosphere and bulk soils. The results indicated that in the bean rhizosphere soils, TOC, DOC and MBC increased significantly (p<0.01), whereas pH decreased significantly (P<0.01). Copper extracted using several chemical extractants in the rhizosphere were significantly (p<0.05) lower than in the bulk soils. In the rhizosphere soils, Cu associated with organic matter increased 15.7%, whereas Cu associated with carbonates, exchangeable Cu, Cu associated with manganese-iron oxides, and residual Cu decreased 19.5, 19.6, 14.7, and 4.7 respectively. The results indicated that correlation between residual Cu with extracted Cu using DTPA-TEA, AB-DTPA and Mehlich 3 were significant (p<0.05) in both the rhizosphere and bulk soils. Correlation between concentration of Cu in bean and extracted Cu using DTPA-TEA, AB-DTPA and Mehlich 3 were significant (p<0.05) in both the rhizosphere and bulk soils. The result showed that significant correlation (p<0.05) were found between yield and uptake indices and Cu associated with organic matter and between concentration of Cu with residual Cu in the bean rhizosphere. The results of this research illustrated that availability of Zn and its fractions in the rhizosphere soils was different from the bulk soils. Therefore, the rhizosphere soil would be recommended in the study on availability of Cu after planting.