Abstract

The aims of this thesis were to investigate (i) the influence of soil factors on Cd concentration in carrots, (ii) the effects of lime on Cd solubility in soils and on Cd concentrations in crops, (iii) the correlation between Cd concentrations in crops in liming experiments and soil factors, i.e. Cd species in soil solution and soil extracts. Common arable crops, carrots and associated soils, soils and saturation extracts from eight liming experiments were studied. The soil pH was the best predictor of carrot Cd concentration. Liming had inconsistent effects on crop Cd concentrations. There was a decrease in crop Cd at sites with high crop Cd concentrations, but at sites with low Cd the Cd concentration in the crop increased. The Cd2+ solubility in the soils investigated was mainly controlled by soil pH and there was no detectable increase in Cd solubility due to additions of Ca(NO3)2 or of lime at higher pH levels. At sites with low crop Cd concentrations, the concentration of Cd in soil solution and batch extracts was also low. This indicates a low availability of metals in the soil, which can lead to micronutrient deficiency and a resultant decrease in biomass or to a release of exudates and a resultant increase in metal bioavailability. There were both visible Mn-deficiency symptoms and/or yield decreases in two of the experiments. It is probable that both plant factors and soil factors affect the solubility and availability of Cd. The Cd concentrations in crops were different between sites and in most cases larger than the effect of liming. The correlation between parameters in the saturation extracts and crop Cd was poor. Hence, analysis of soil solution extracts proved not to be a good tool for predicting crop Cd concentrations at low Cd concentrations in the soil solution. The recommendation coming out of this thesis is to lime soils that have low soil pH and that are known to give high Cd concentrations in crops. Soils with low pH and low crop Cd concentrations should only be given minor or no additions of lime. The thesis also indicates that site selection may be more effective than liming in managing crop Cd.

Keywords

carrots; cereals; potatoes; pH; soil Cd; soil solution; Cd solubility; Ca 2+ competition; site selection; saturation extracts

Published in

Acta Universitatis Agriculturae Sueciae. Agraria
2002, number: 341
ISBN: 91-576-6192-8
Publisher: Swedish University of Agricultural Sciences

SLU Authors

• Jansson, Gunilla

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Soil Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/107629