Submitted to: International Symposium on Biogeochemistry of Trace Elements Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 1, 2001
Publication Date: July 27, 2001
Technical Abstract: Cadmium is present in all plants, crops differ in their tendency to accumulate Cd, with sunflower, flax and durum wheat containing relatively high levels when grown on uncontaminated farm soils.The uptake of Cd by plants is controlled by many different factors, with soil properties playing a large role. Among the soil properties controlling Cd availability are soil parent material, soil pH, salinity, and organic matter content. This study attempts to further clarify controlling soil factors using a large set of paired samples of soil and grain collected across the state of North Dakota, U.S.A. Corresponding soil and mature durum wheat grain were collected from 150 fields 12 24 counties in 1994 using clean techniques. Soil total and extractable, and total grain elements were analyzed by ICP-AES, and water soluble soil anions by ion chromatography. Grain Cd correlated more closely to DTPA-extractable Cd (Pearson r = 0.512) and Na-pyrophosphate-extractable soil Cd (Pearson r = 0.512) than to the NH4Cl-extractable soil Cd (Pearson r = 0.336), and log transforming the data did not alter this relationship (r = 0.567, 0.577 and 0.444 respectively). Previous studies have shown the importance of Soil Organic-C (SOC), chloride and sulfate in either reducing uptake of grain Cd (SOC) or facilitating that uptake. To determine the relative importance of these factors in our data set, a series of regression analyses were undertaken. Using a linear model grain-Cd was weakly related to SOC, and more strongly related to sulfate than chloride. 41% of the variance was explained by these soil variables. In North Dakota it appears that the effects of salinity were more important controls on grain Cd than SOC.