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Cadmium availability from granulated and bulk-blended phosphate-potassium fertilizers
S H Chien1, G Carmona, L I Prochnow
1Resource Development Division, IFDC, P.O. Box 2040, Muscle Shoals, AL 35662, USA. nchien@ifdc.org
Journal of Environmental Quality
|October 11, 2003
Summary
Granulating potassium chloride (KCl) with cadmium (Cd)-containing phosphorus (P) fertilizers significantly increases Cd uptake in crops compared to bulk-blending. This highlights the importance of fertilizer formulation in managing soil heavy metal contamination.
Area of Science:
- Soil Science
- Environmental Chemistry
- Agronomy
Background:
- High chloride (Cl) in irrigation water increases soil cadmium (Cd) uptake by crops.
- Soluble ion-pair complexes of Cd with Cl in soil solution are responsible for enhanced Cd uptake.
Purpose of the Study:
- To test if KCl in granulated PK fertilizers enhances Cd uptake from Cd-containing P fertilizers due to close contact.
- To compare Cd uptake from granulated vs. bulk-blended PK fertilizers.
Main Methods:
- Single superphosphate (SSP) with Cd was granulated with KCl.
- Granular KCl was bulk-blended with SSP or Cd-free monocalcium phosphate (MCP).
- Upland rice, soybean, and signalgrass were grown in an acid Ultisol treated with these fertilizers.
Main Results:
- Agronomic effectiveness for crop yield was similar for granulated and bulk-blended fertilizers.
- Cd concentrations in plant tissues were lower for MCP than SSP.
- Granulated (SSP + KCl) resulted in significantly higher Cd concentrations in plant tissues (except upland rice grain) than bulk-blended (SSP) + (KCl).
Conclusions:
- Fertilizer granulation significantly impacts soil cadmium bioavailability.
- Close contact between KCl and Cd-containing P fertilizers in granules enhances crop Cd uptake.
- Fertilizer management strategies should consider formulation to mitigate heavy metal uptake.