New phosphorus fertilizer amendments

PA 151 of 2013 amends the phosphorus use restrictions for turf fertilizers.

PA 299 of 2010 was the first set of phosphorus restrictions to the original Michigan Fertilizer Law and applied specifically to lawn fertilizers containing phosphorus. To learn more about this law, read the news article Michigan Fertilizer Act helps protect water quality. These amendments provided many needed updates for water quality protection.

While PA 299 of 2010 was being passed by the legislature and signed into law, it was apparent that a number of amendments were needed. Several definitions from PA 299 of 2010 were in need of technical updates to be more in line with existing legislation and definitions. In addition, natural turf fertilizers were not included in the low-phosphorus application exemption that was offered to biosolids and manure-based products. Despite a strong niche market and demand for natural lawn fertilizers, many natural lawn fertilizer ingredients have phosphorus and could not be used on turf (except when a soil test shows the need or for new turn establishment). Visit the Michigan State University Extension website for soil test recommendations for phosphorus applications to turf grass.

PA 151 of 2013 was signed into law on November 5, 2013. These amendments dealt with the request to update terminology and clarify and incorporate omitted materials. It changed the term “finished sewage sludge product” to “biosolids” but kept the same definition. A biosolid is a product consisting in whole or in part of sewage sludge that is distributed to the public and this is disinfected by means of composting, pasteurization, wet air oxidation, heat treatment or other means. The new law omitted “organic manure” and added “natural fertilizer” with a definition of “a substance composed only of natural organic, natural inorganic, or both types of fertilizer materials and natural fillers.”  The law then added “natural fertilizer” to its list of materials that may be applied at a rate of not more than 0.25 pounds phosphorus per 1,000 square feet per application.

So what is a “natural inorganic fertilizer” and “natural organic fertilizer”? The Association of American Plant Food Control Officials’ Official Publication ( defines each as:

Natural inorganic fertilizer – a mineral nutrient source that exists in or is produced by nature and may be altered from its originals ate only by physical manipulation.

Natural organic fertilizer – materials derived from either plant or animal products containing one or more elements (other than carbon, hydrogen and oxygen) which are essential for plant growth. These materials may be subjected to biological degradation processes under normal condition of aging, rainfall, suncuring, air drying, composting, rotting, enzymatic or anaerobic/aerobic bacterial action, or any combination of these. These materials shall not be mixed with synthetic materials or changed in any physical or chemical manner from their initial state except by manipulations such as drying, cooling, chopping, grinding, shredding, hydrolysis or pelleting.

The original 2010 amendments were the first to define no application zones adjacent to surface water bodies. The 2013 amendment changes the law from “shall not apply fertilizer to turf less than 15 feet from any surface water” to “shall not apply within 15 feet . . .”

The original 2010 amendments grandfathered in community’s existing ordinances in Michigan communities. This still applies.

For more information, MSU Extension and Michigan Department of Agriculture & Rural Development (MDARD) also recorded a webinar on the 2010 Fertilizer amendments.

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