How Can Farmers Determine the Effects of Various Manure Types on the Soil?

Tanja Folnovic

Agronomy Expert

While there are many farm innovations that make life easier or get the job done faster, sometimes nothing beats the old-fashioned way. At least, that’s how many farmers feel when it comes to fertilizing their crops. Manure is sometimes better than synthetic fertilizers due to the carbon compounds (organic materials) that build soil structure which synthetic fertilizers cannot do.

Although the use of manure has generally declined on many farms over the past 50 years due to farm specialization with increasing separation of crop and livestock production, cost of transporting manure, and increased availability of synthetic fertilizers, manure is a valuable fertilizer for any farming operation which provide many benefits to soil and crop production generally.

Continued use of manures builds organic matter in soils and improves soil structure. This modification of soil structure helps improve water holding capacity, aeration, friability, and drainage. In addition, many trace nutrients needed for optimum plant growth are available from manures. Plant nutrients are also released more slowly and over a longer period of time than from most commercial fertilizers.

Manure is also a valuable source of organic matter. Increasing soil organic matter improves soil structure, increases the water-holding capacity of coarse-textured sandy soils, improves drainage in fine-textured clay soils, provides a source of slow release nutrients, reduces wind and water erosion, and promotes the growth of earthworms and other beneficial soil organisms.

Manure Application

Proper use of manure and compost is essential from both a production and environmental standpoint. Manure should never be applied fresh (raw) on the field. Fresh manure is high in soluble forms of N, which can lead to salt build-up and leaching losses if over applied. Fresh manure may contain high amounts of viable weed seeds, which can lead to weed problems. In addition, various pathogens such as E. coli may be present in fresh manure and can cause illness to individuals eating fresh produce unless proper precautions are taken.

Fresh, non-composted manure will generally have a higher N content than composted manure. However, the use of composted manure will contribute more to the organic matter content of the soil.

Applying rates that are too low can lead to nutrient deficiency and low yields. On the other hand, a too high rate can lead to nitrate leaching, phosphorus runoff, accelerated eutrophication of lakes, and excessive vegetative growth of some crops. Thus, understanding how to manage manure is important for any farming operation with livestock that relies on manure as a major source of nutrients, as well as for crop producers who have access to an economical supply of manure, compost, or other organic nutrient sources.

Nutrient Composition of Manure

Many different types of manure are available for crop production. It's assumed that most farmers will be using solid manure with or without bedding. It is important to remember that nutrient contents in manures vary widely according to the age of the animals, feed used, moisture content, degree of decomposition, and the amount of litter or bedding material mixed in with the manure. The only really accurate way of determining the nutrient content of the manure is through laboratory analysis.

Nitrogen Phosphorus Potassium Calcium Magnesium Organic matter Moisture content
  (N) (P2O5) (K2O) (Ca) (Mg)
FRESH MANURE % % % % % % %
Cattle 0.5 0.3 0.5 0.3 0.1 16.7 81.3
Sheep 0.9 0.5 0.8 0.2 0.3 30.7 64.8
Poultry 0.9 0.5 0.8 0.4 0.2 30.7 64.8
Horse 0.5 0.3 0.6 0.3 0.12 7.0 68.8
Swine 0.6 0.5 0.4 0.2 0.03 15.5 77.6
Cattle 2.0 1.5 2.2 2.9 0.7 69.9 7.9
Sheep 1.9 1.4 2.9 3.3 0.8 53.9 11.4
Poultry 4.5 2.7 1.4 2.9 0.6 58.6 9.2

Average percentage of nitrogen (N), phosphorus (P2O5), and potassium (K2O) commonly found in animal manures

Nutrient Availability from Manure

The analysis of manure or compost provides total nutrient content, but the availability of the nutrients for plant growth will depend on their breakdown and release from the organic components. Generally, 70 to 80% of the phosphorus (P) and 80 to 90% of the potassium (K) will be available from manure the first year after application.

When applied to soil, manure and compost undergo microbial transformations that release plant-available N over time. Volatilization, denitrification, and leaching result in N losses from the soil that reduce the amount of N that can be used by crops. Therefore it's recommended to incorporate manure within 12 hours of application to avoid excessive ammonia losses.

As managing of manure is important for proper crop growth, so tracking of applied manure is important for proper farm management. Agrivi system allows farmers to make inputs of applied manure per crop productions and fields as well as entering chemical soil analysis result to know how much manure to apply. The system gives you also powerful analysis of applied manure per all your fields which are color coded according to applied amount.


Agrivi Field analytics of applied manure

Manure is an excellent fertilizer containing nitrogen, phosphorus, potassium and other nutrients. It also adds organic matter to the soil which improves soil structure, aeration, soil moisture-holding capacity, and water infiltration.

So, use manure to improve soil fertility and Agrivi system to improve your complete crop production!


Text sources: University of Minnesota


Image sources: EcoChem