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Using Fluxmeters to measure Cd drainage in cropping system
Col Gray, AgResearch, March 2021
Introduction
The industry continues to support the Cadmium Management Group in developing our scientific understanding and knowledge of soil cadmium. Our understanding of very gradual soil accumulation relies on the modelling and assessment of soil fluxes, including potential leaching losses.
The modelled losses require more validation and a study was commissioned to analyse archived soil water (drainage) samples to assess cadmium losses from cropping soils.
The measured cadmium values were compared to the estimates calculated using the methods used in modelling. From the seven sampling sites, results were generally below the detection limit. Cadmium in drainage was only occasionally detected from two sites and no detection occurred at four other sites. Drainage from one site (with six fluxmeters) showed very low cadmium leaching loss, ranging from 0.06 - 0.18 μg/L (millionths of a gram per litre). On this one site where cadmium was detected in drainage water, the levels were low, but similar to the estimates expected based on the soil cadmium levels. However, there was insufficient data from these assessments to make a robust evaluation of the modelled leaching losses.
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Cadmium Balance Model Decision Support Tool (CadBal): A web-based tool to help land managers make decisions on how to manage cadmium accumulation in agricultural soils.
