This article is part of the series, Using Compost on the Farm. Composting keeps organic materials out of the landfill, prevents water quality impacts resulting from unmanaged debris/manure piles, and provides beneficial re-use of organic waste products. Compost can improve soil health by increasing its organic matter, supporting nutrient cycling, and improving plant water availability. Compost can provide some of the nutrients needed for plant growth, including nitrogen and phosphorus. For all of these reasons and more, compost use and testing are considered best management practices in Florida agricultural production.
Why test compost?
Compost testing is a best practice to protect water resources
Compost nutrient testing provides information that growers can use in producing crops and protecting water resources. The Florida Department of Agriculture and Consumer Services (FDACS) considers compost testing an Agricultural Best Management Practice (BMP) across a range of operations, including small farms and specialty livestock, cattle and equine operations, and vegetable and agronomic crops. Specifically, BMP 1.6.1 encourages growers to document the total Nitrogen (N) and total Phosphorus (P) content of compost they plan to use on their farm or ranch.
Testing gives growers insight into compost nutrient content
In the 2025/26 growing season, UF/IFAS Extension Martin County worked with growers and compost producers to measure the total and plant available nutrient content of their compost. Through an Ag BMP Mini-Grant funded by FDACS, we were able to provide free compost testing. The growers we worked with viewed compost as a beneficial amendment, though not all had yet taken the step of compost testing. Through the project, they gained information about their compost quality through testing services offered by UF. When surveyed after the project, participants reported that they plan to continue submitting their compost samples for testing annually.
UF compost testing services
The UF/IFAS Analytical Services Laboratories (ANSERV Labs) offers two tests recommended for analysis of compost: the Compost test and the Container media test.
Compost test
The Compost test measures the total N and P content of compost, as required for growers who enroll in the FDACS Compost BMP. When preparing their sample, the grower can select a target crop from the list of crops shown on the back of the sample submittal form. If a crop is specified from the list provided, the results will include fertilizer recommendations specific to that crop, along with a suggested compost application rate to deliver the crop-specific nutrients. For example, our results ranged from 17 to 45 tons/ac recommended compost application rates for N, depending on the crop and the nutrient content of the compost sample being tested. The suggested compost application rates are only estimates, as some nutritional content may be lost from the compost during or before application, while other nutrients may not be available for plant uptake.
In addition to N and P content, the compost test also measures the pH, moisture content, percentage of solids, and other parameters. Through their use of the UF Compost test, growers can quantify the nutrients they are applying to their fields through compost amendment, participate in Florida’s compost testing BMP, and gain insight into the role of compost in supplying crop nutrients.
Container media test
As mentioned above, at any given time, only a portion of the total nutrient content within compost will be available for plant uptake. The nutrients provided in compost are made available to crops through nutrient cycling processes. The amount of total N and P crops are able to take up from compost will vary, depending on biological, physical, and chemical activity within the soil. Therefore, growers may also choose to submit a compost sample for the ANSERV Container Media Test. The Container media test serves as a tool for both containerized plant producers and producers amending their farm/ranch soils with compost. The test quantifies a sample’s plant-available nutrient content, including the mg/L of nitrogen in the form of nitrate (NO3N), P, K, Ca, and Mg.
Conclusions
Florida growers gain insight into the nutrient content that compost amendment can provide to their crops and fields by submitting compost samples for testing. The UF/IFAS ANSERV lab offers two tests of value for compost analysis: 1) the Compost test; and 2) the Container media test. To learn more or submit a sample, visit the ANSERV Labs website and download the appropriate sample submittal forms.
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