Evaluation of main soil properties affecting Cd concentrations in soil and wheat grains on some calcareous soils of Khuzestan Province

Soil properties are influencing the amount and bioavailability of heavy metals in soil. Therefore, determining soil characteristics affecting cadmium (Cd) solubility and its uptake by plants are of great importance. The objective of this study was to evaluate the relations between main soil properties and Cd concentrations in soil and wheat grains in 4000 km2 wheat farms. A number of 255 pair soil and grain coordinate samples were taken in an weighing sampling scheme. Some soil characteristics including pH. EC, CEC, organic carbon (OC), clay content, lime content (TNV), available P, soil Cd and grain Cd concentrations were measured. The results indicated that the average TNV in the studied soils was more than 46 percent. Average total and DTPA-extractable soil Cd and grain Cd concentrations were 1.47, 0.085, and 0.7 mg kg-1, respectively. In the studied calcareous soils, total Cd concentrations had significant correlation with TNV (P≤0.01), available P (P≤0.01), CEC (P≤0.05), and OC (P≤0.05). The DTPA-extractable Cd had significant correlation with OC (P≤0.01), pH, and clay content (P≤0.05). Significant correlations were also found between grain Cd concentrations with OC (P≤0.05), CEC (P≤0.01), and DTPA-extractable Cd (P≤0.05). However, the total Cd, soil pH and lime content (TNV) had no significant (P≤0.05) correlations with wheat grain Cd in the study area. However, the correlations between soil properties and two wheat cultivars (Bread and Durum) were different. A significant (P≤0.01) correlation was obtained between durum grain Cd and OC, CEC, and DTPA-extractable soils Cd. For bread Cd in grains, a significant (P≤0.01) correlation was found between more soil properties, including OC, CEC, and DTPA-extractable Cd, TNV and clay content. The Pearson coefficient values for durum wheat cultivar shows that, the OC, CEC and Cd-DTPA had more effects on durum wheat than bread wheat cultivar. It could be concluded that plant-availability of soil Cd as effected by soil properties and wheat cultivar