Zinc Fertilizer Seal of Approval
Quality Seal Initiative
While zinc fertilizers enrich the soil and crops, some inorganic fertilizers may contain impurities – including cadmium and lead – at levels that could be inappropriate, generally derived from the source materials comprising the fertilizers.
To address contamination concerns, we have partnered with Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) to develop a set of contaminant limit values for arsenic, cadmium, chromium, lead, and mercury in zinc fertilizers. We award the zinc fertilizer seal of approval to demonstrate that fertilizers meet the impurity guidelines outlined in the CSIRO code of practice, based upon verification requirements, including submission of product specifications/analyses and third-party testing.* At the International Zinc Association, we are committed to promoting safe, beneficial zinc fertilizers.
Qualification Specifications
Based upon the Code of Practice for zinc fertilizer developed for the International Zinc Association (IZA), Table 1 sets the specifications for the limits of impurities in zinc sources for use in fertilizer. Table 2 provides the minimum level of zinc in common zinc fertilizer products.
Table 1. Limits for impurities in Zn fertilizers
| Element | Maximum allowed concentration per 1% Zn (mg/kg) | Maximum allowed concentration per kg Zn (mg element/kg Zn) | Maximum allowed concentration in ZnO (mg element/kg pure ZnO) | Maximum allowed concentration in ZnSO4 (heptahydrate) (mg element/kg pure ZnSO4.7H2O) |
| Arsenic | 60 | 6000 | 4820 | 1365 |
| Cadmium | 6.8 | 680 | 546 | 155 |
| Chromium | 81 | 8100 | 6508 | 1843 |
| Mercury | 1.3 | 130 | 104 | 30 |
| Lead | 5.3 | 530 | 426 | 121 |
Table 2. Minimum zinc content required
| ZnO | ZnSO4.7H2O | ZnSO4.H2O | |
| Zinc | % | 23% | 33% |
How To Qualify
To qualify for the Zinc Quality Seal, the following audit requirements must be met by the company:
- Submission of company product specifications for zinc and impurities
- Submission of product may be requested for review and comparison with the impurity limits
- The company must be a Member/Affiliate Member of IZA in good standing in order to participate
The Seal of Approval will be granted on a conditional basis once the product specifications are deemed to meet the requirements. A company’s use of the Seal can be stopped at any time if the audit requirements, and standards listed above are not met per the assessment of the IZA.
Resources
Code of Practice
Qualification Specifications
Contact Us
To learn more about our program or become a member,
email Zinc Nutrient Initiative Director Dr. Soumitra Das at sdas@zinc.org.
*The information contained in the Code of Practice and any documentation in relation to the Quality Seal only comprises statements of a general nature based on scientific research. Such information is not intended to address the specific circumstances of any particular individual, entity, purpose or situation.
IZA does not owe any duty of care to you, and makes no representations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability or availability of such information for any particular purpose or situation. Any reliance you may place on such information is therefore strictly at your own risk, and no reliance or actions must be made on such information without seeking prior expert professional, scientific, and technical advice.
Except to the extent such liability cannot legally be excluded, IZA (including its employees, consultants, and Members) shall in no event be liable to any person for any consequences whatsoever, including but not limited to any losses, damages, costs, expenses or any other compensation, arising directly or indirectly from relying on the Code of Practice, any documentation in relation to the Quality Seal (in part or in whole) and any information or material contained therein.