CompostIowa Fertilizer Law - Delegated by the Iowa Department of Agriculture and Land Stewardship (IDALS)

This fact sheet has been prepared by the Iowa Waste Reduction Center (IWRC) to assist those selling compost in Iowa in complying with the state regulations.  This document is intended solely as guidance and is not a substitute for reading applicable regulations.

Soil Conditioner and Compost

A soil conditioner is any substance which when added to the soil or applied to plants will produce a favorable growth, yield, or quality excluding fertilizers, pesticides, manure, and calcium and magnesium carbonate material.  A soil conditioner for the purpose of this summary is also referred to as compost. 


A license must first be obtained to manufacture, mix, blend, sell, or distribute any soil conditioner/compost in Iowa.  The cost of a license is $10 for each place of manufacture or distribution where soil conditioner/compost products are sold or distributed in Iowa.  To obtain a license:

To maintain a license:

  • Repay the $10 license fee annually by July 1 of each year.
  • Produce a uniform mixture of soil conditioner/compost at all times.  When two or more mixes are delivered in the same load they must be mixed thoroughly and uniformly unless they are in separate compartments.


Each brand or grade (the percentage of total nitrogen, available phosphorus or P2O5 or both, and soluble potassium or K2O or both) of soil conditioner/compost must be registered before being offered for sale, sold, or otherwise distributed in Iowa.  Registration requirements for the sale or distribution of soil conditioner/compost in Iowa include the following:

Include current labels (as described below) for all products being registered.


When soil conditioners/compost are sold or distributed in bags or containers, the following information must be affixed to the container in legible, printed form either on tags affixed to the end of the package or directly on the package:

  • Net weight
  • Name and address of the registrant
  • Name of the product
  • Brand
  • Grade
  • Guaranteed Analysis (as described below)
  • The name or chemical designation and percentage of each of the active ingredients.

If distributed in bulk, the shipment must include a written or printed statement with the information required above. If a custom mix is created specifically for the customer the purchaser’s name and address must also be included.

Guaranteed Analysis

An analysis of the soil conditioner/compost must be completed prior to the sale or distribution of the product to guarantee plant nutrient content.  The minimum percentage of plant nutrients must be claimed and reported as total Nitrogen (N), available Phosphorus (P) or P2O5 or both, and soluble Potassium (K) or K2O or both.  Minimum percentages must be included in the guaranteed analysis and registered as such. 

Any additional plant nutrient elements contained in a soil conditioner/compost that are claimed in writing must be identified in the guarantee expressed as the element and will be subject to inspection and analysis.  Guarantees must be made on the elemental basis and shown on the application for registration. 

Inspection Fees

The licensee of soil conditioners/compost sold or distributed in the state must pay an inspection fee that is annually fixed by the secretary of agriculture and will not exceed twenty cents per ton.  Inspection fees must be filed no later than January 31 and July 31 of each year on the following form:

  • The Fertilizer Inspection Fee Report must include a semi-annual statement including the number of net tons of soil conditioners/compost distributed in Iowa by grade for each county during the preceding six months.


Failure to comply with this rule when selling soil conditioner/compost could result in fines, fees, seizure of products, “stop sale” orders, or revocation of registration and/or license.  In addition, misleading or false statements whatsoever as well as adding inert or damaging filler material to soil conditioners/compost is unlawful and could also result in penalties.