科研之友
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摘要
The application of commercial phosphate fertilizers containing Cd as an impurity is an important source of Cd to agricultural soils. The changes in the Cd status and its bioavailability in soils taken from a field trial were investigated after several years of application of fertilizers with a range of Cd contamination levels to soils. Various soil pH regimes were achieved by liming. The isotopic dilution technique was used to determine both the plant available (L-value) and isotopically exchangeable (E-value) Cd pools in soils. Firstly, we found that the L-values after 10 year of application were significantly higher at pH 5.0 than at pH 6.0, and this was reflected in the increased Cd uptake by wheat at the lower pH. There was no significant effect of the rate of soil Cd application on the L-values. Although long-term use of Cd enriched P-fertilizers increased the total concentration of Cd in soil, the impact on wheat production was insignificant. Most cultivated soils in Norway are maintained at soil pH between 5.5 and 6.5 by frequent liming. That brings up the second interesting finding, the possible impurity of lime used in this experiment. The lime was not analysed, as it was unexpected that liming might raise the total content of soil Cd substantially. That seems, however, to have been the case for this experiment since we find increase of total Cd even in the low-Cd input blocks of the trial.
- 出版日期2011-11
