Section 001-350-3 - PLANT NUTRIENTS1. In addition to Total Nitrogen (N), Available Phosphate (P2O5), and Soluble Potash (K2O), other plant nutrients when mentioned in any form or manner shall be registered and shall be guaranteed. Guarantees shall be made on the elemental basis, sources of the elements guaranteed and proof of availability shall be provided to the Maine Department of Agriculture upon request. Except guarantees for those water soluble nutrients labeled for ready to use foliar fertilizers, ready to use specialty liquid fertilizers, hydroponic or continuous liquid feed programs and guarantees for potting soils, the following percentages represent the minimum concentrations for any secondary or minor nutrients contained in fertilizers which may be accepted for registration: | Element | Minimum Conc., % |
| Calcium (Ca) | 1.0000 |
| Magnesium (Mg) | 0.5000 |
| Sulfur (S) | 1.0000 |
| Boron (B) | 0.0200 |
| Chlorine (Cl) | 0.1000 |
| Cobalt (Co) | 0.0005 |
| Copper (Cu) | 0.0500 |
| Iron (Fe) | 0.1000 |
| Manganese (Mn) | 0.0500 |
| Molybdenum (Mo) | 0.0005 |
| Nickel | 0.0010 |
| Sodium (Na) | 0.1000 |
| Zinc (Zn) | 0.0500 |
2. Only fertilizers containing one or more of the above listed plant nutrients, with guaranteed amounts meeting the minimum concentrations, may be accepted for registration. Any of the above listed plant nutrients which are guaranteed must appear, in the order listed, immediately following guarantees for the primary nutrients of nitrogen, phosphate and potash.01-001 C.M.R. ch. 350, § 3