Metals | ppm per 1% P2O5 | ppm per 1% Micronutrients3 |
1. Arsenic | 13 | 112 |
2. Cadmium | 10 | 83 |
3. Cobalt | 136 | 2,2284 |
4. Lead | 61 | 463 |
5. Mercury | 1 | 6 |
6. Molybdenum | 42 | 3004 |
7. Nickel | 250 | 1,900 |
8. Selenium | 26 | 180 |
9. Zinc | 420 | 2,9004 |
To use the Table:
Multiply the percent guaranteed P2O5 or sum of the guaranteed percentages of all micronutrients (Iron, Manganese, Zinc, etc.) in each product by the value in the appropriate column in the Table to obtain the maximum allowable concentration (ppm) of these metals. The minimum value for P2O5 utilized as a multiplier shall be 6.0. The minimum value for micronutrients utilized as a multiplier shall be 1. If a product contains both P2O5 and micronutrients multiply the Guaranteed percent P2O5 by the value in the appropriate column and multiply the sum of the guaranteed percentages of the micronutrients by the value in the appropriate column. Utilize the higher of the two resulting values as the maximum allowable concentrations.
Footnotes:
1 Woltering, Daniel M. 2004. Health Risk Assessment for Metals in Inorganic Fertilizers: Development and Use in Risk Management. In Environmental Impact of Fertilizer on Soil and Water. Hall, William L. Jr. and Wayne P. Robarge, Editors. American Chemical Society Symposium Series No. 872. p124-147.
2 These guidelines are not intended to be used to evaluate horticultural growing media claiming nutrients but may be applied to the sources of the nutrients added to the growing media.
3 Micronutrients (also called minor elements) are essential for both plant growth and development and are added to certain fertilizers to improve crop production and/or quality. These micronutrients are defined by AAPFCO's Official Fertilizer Term, T-9.
4 Only applies when not guaranteed.
5 Includes all compost products separately or in combination with biosolids, manure or manipulated manure, even those registered as fertilizers (making nutrient claims).(Official 2003)
01-001 C.M.R. ch. 350, § 8