Benefits of Manure Fertilizers and Analysis

Manure from livestock has been used by farmers and gardeners since the beginning of farming, with evidence of the benefits of manure are documented dating back nearly 8,000 years.  Manure can help improve soil, but there are a couple common misconceptions about its benefits.  An often-overlooked factor about manure is, that unlike the majority of fertilizers we use on the farm, manure does not come with a guaranteed analysis. We need to know the nutrient make-up of the manure we’re adding, so we can determine how much additional fertilizer is needed to have a good yield.  The second misconception goes along with the first, which is that manure is applied solely as a nutritional supplement.  Not only does manure work similalry to commercial fertilizers, but it also improves soil structure.  Adding manure to a sandy soil improves the soil’s water holding capacity.  Adding manure to a clay soil improves the soil’s drainage by increasing macropore space.  The last misconception is that all manure from farm animals is safe for food crops.  While pig manure will improve soil structure and provide nutrients to our crops, it is not safe for food crops because it may contain parasites.  This is also true for dog, cat, and human waste.  Even for other manures, such as cow and chicken waste, you should follow the USDA’s recommendations for applying manure for food crops.

Spreading manure for crop and pasture fertilization has a number of benefits, but before you apply, find out the nutrient levels to ensure adequate fertilization. Credit AdobeStock 283112235

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It’s hard to guess the nutrient content of different manures.  The nutrient content varies depending on a number of factors including age and sex of livestock, consistency of the manure (Is it a slurry, sludge, solid, or liquid?), and whether or not bedding material is mixed with the manure.  North Carolina State University published a table with common nutrient content of livestock waste.  Even though this is a helpful table, it only lists an average of nutrient contents of different types of manures.  It is not specific to manure from your livestock or other local farms.  Fortunately, the University of Florida has a lab for that.  The UF/IFAS Livestock Waste Testing Lab analyzes manures for nutrient content and provides supplemental fertilizer rate recommendations based on the analysis and the crop to be grown.  Please be mindful that the recommendations are based on the nutrient needs of the crop to be grown, not the available nutrients in the soil the crop will be grown in.  You should also send a soil sample to the UF/IFAS Extension Soil Testing Laboratory to determine the nutritional needs of your soil.

Analytical Services Laboratories. Photo taken 12-11-23.

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Livestock manures improve the structure, drainage, water holding capacity, and organic matter content of our native soils.  They can also provide some valuable nutrients to our crops.  Follow the simple recommendations listed in this article and your farm can benefit from the positive effects of adding manure to your fields.