Michigan Compiled Laws, Chapter 324. Natural Resources and Environmental Protection § 324.8503

(a) Total nitrogen (N).____%

Available phosphate (P₂O₅).____%

Soluble potash (K₂O).____%

(b) When applied to mixed fertilizers, grade shall be given in whole numbers only. However, specialty fertilizers with a guarantee of less than 1% of total nitrogen, available phosphate, and soluble potash may use fractional units. Fertilizer materials, bone meal, manures, and similar materials may be guaranteed in fractional units.

(c) When applied to custom blends, grade can either be given in whole numbers or in numbers expressed to the nearest 1/10 of a percent in the form of a decimal in the analysis.

(d) For unacidulated mineral phosphatic material and basic slag, bone, tankage, and other organic phosphatic materials, the total phosphate or degree of fineness, or both, may also be guaranteed.