Review of the Cadmium Management Strategy

The Cadmium Management Group (CMG) representing regional councils, primary sector groups and central government, is convened by the Ministry for Primary Industries to manage cadmium in agriculture. A refreshed Cadmium Management Strategy has been published with the CMG's statement of how and why cadmium will be managed going forward.

What is cadmium?

Cadmium is a naturally occurring heavy metal in the earth's rocks, soils, water and air. Phosphate fertiliser, which is produced from phosphate rock, is the primary source of very gradual cadmium accumulation in agricultural soils. For this reason, the fertiliser industry has enacted a voluntary limit on the levels of cadmium in fertilisers.

Objective of the Cadmium Management Strategy

The strategy is designed to protect human health, protect the environment, maintain trade access, support a vibrant productive sector, and maintain flexibility in land use options over the long term.

The strategy approach focuses on:

• governance and reporting
• monitoring e.g. fertiliser, soils, food, environment
• management e.g. fertiliser, soils, food production, advice and information
• research e.g. food production, land use flexibility, understanding pathways of movement
• scanning international information to identify new emerging issues.
• monitoring cadmium levels in phosphate fertiliser and soil.

The fertiliser industry has a maximum voluntary industry standard of 280 mg Cd /kg P, however, since the limits was first introduced, the fertiliser cadmium levels have dropped to a long-term current average value in the order of 180 mg Cd/kg P.

Under the strategy, there has been reporting on fertiliser cadmium content, and also extended soil sampling for cadmium across New Zealand. This has provided greater transparency and understanding of cadmium levels in the environment.

Research investment

A series of significant research programmes have been completed investing approximately $1 million in funding from the members. The programme has developed science capability, while engaging and coordinating a wide range of research. Losses of cadmium in leaching and surface runoff have also been better quantified. Plant uptake by different species and varieties, including by livestock forage crops such as plantain and chicory have been examined.

New Zealand specific soil characteristics and crop management options to reduce soil cadmium uptake have also been researched.

Controlling soil accumulation - The Tiered Fertiliser Management System (TFMS)

The Tiered Fertiliser Management System is a component of the Strategy, which provides a mechanism for controlling soil cadmium accumulation. It has the principal purpose of managing phosphate fertiliser applications to reduce soil cadmium inputs as soil cadmium increases. It sets an agreed maximum soil cadmium limit and allows managed reductions in soil cadmium accumulation to ensure the agreed limit will not be exceeded.

In response to an independent review recommendation to reduce soil cadmium accumulation further at Tiers 2 and above, the TFMS has been revised to reduce the maximum recommended rates for phosphate fertilisers at these tiers. The review also asked for greater transparency in the assumed maximum cadmium content in the different categories of phosphate fertiliser products. The values are the basis for limits on phosphate applications and so the conservative nature of these assumptions are now more transparent in the TFMS.

Crop management practices to farmers

The refreshed strategy has a greater focus going forward on education and promotion of crop management practices to farmers.

Additional crop management advice and information programmes for farmers are being developed. These build on information developed from the New Zealand research programmes with the view to minimise cadmium accumulation in the food chain in the event of future land use changes on higher cadmium soils. While controlling soil cadmium accumulation is essential, the awareness of good farm management practices and the factors influencing plant uptake-regardless of soil cadmium concentration-remains an integral part of the management of soil cadmium.

Further Information:

MPI - Protection & Response - Cadmium

FANZ - Managing Contaminants