Manure as a Source of Crop Nutrients and Soil Amendment

What Is Manure Worth Compared to Commercial Fertilizer?

Animal manure is considered an agricultural commodity that can be utilized as a fertilizer source for pastureland, cropland and hay production. Manure is recognized as an excellent source of the plant nutrients nitrogen (N), phosphorus (P) and potassium (K). In addition, manure returns organic matter and other nutrients such as calcium, magnesium and sulfur to the soil, building soil fertility and quality.

Any financial valuation of manure would be dependent on the market value of the N, P, K, and other plant nutrients that the manure is replacing, organic matter as a soil amendment, and the nutrient needs of the crops and fields receiving the litter.

The nutrient content of manure will vary depending on animal type and diet, type and amount of bedding, manure moisture content, and storage method. For more information, see the Clemson University publication Livestock Manure Production Rates and Nutrient Content.

Buyers and sellers should have a lab analysis to determine moisture and nutrient concentration of the manure. Generally speaking, liquid manures will contain a lower nutrient content than solid manures, due to the dilution effect. Assuming all nutrients are needed by the crop, higher manure nutrient content corresponds to higher manure value. Higher values help to offset transportation and handling costs.



Manure Composition

Nitrogen in Manure

Nitrogen in manure is found in the organic and inorganic forms. The organic form (slow release) slowly mineralizes providing plant-available N, while inorganic forms (fast release) consist primarily of NH4-N and are immediately plant available. However, inorganic forms are also susceptible to loss through ammonia volatilization during storage and field application. Promptly incorporating the manure into the soil can reduce these N losses. Due to the slow release organic form and potential losses of the inorganic form, not all of the N is available to the crops during the year of application. Nitrogen that is expected to be available to the plant has value as a fertilizer. The N which is lost to the environment or which is not available to the crop in the year it is needed or subsequent years does not have value. The guide “Fertilizer Nutrients in Animal Manure” provides information on the amount of N expected to be available in the 1st year and subsequent years from various manure sources:

Phosphorus and Potassium in Manure

Phosphorus and Potassium in manure are mostly present in the inorganic form. This means that P and K are similar to commercial fertilizer in that they are readily available for plant uptake. Most nutrient management plans are based on a P-Index or P-threshold which may limit manure application on some fields. Therefore, the value of these nutrients is based on crop nutrient needs as determined by a soil test and yield goal.

Micronutrients in Manure

Other nutrients such as calcium (Ca), magnesium (Mg) and sulfur (S) may be found in manure and are beneficial to the soil if a deficiency exists. Both Ca and Mg create an added value by producing a liming effect when added to the soil.

Organic Matter

Organic matter, primarily undigested feed and bacteria in the feces, increases infiltration of water, increases water holding capacity, enhances retention of nutrients, reduces wind and water erosion and promotes the growth of beneficial organisms when added to the soil. Although the value of organic matter is hard to quantify, higher quality soils are associated with increased yields and higher economic returns.

Manure As a Plant Fertilizer

Because manure is not a balanced fertilizer, some plant nutrient needs may be met while other nutrients may be under- or over-supplied. Any nutrient that is undersupplied by a manure application could incur a subsequent fertilizer application cost which would, in effect, lower the net value of the manure. Any nutrient that is oversupplied by a manure application would not have immediate value because it was not needed by the crop.

Additional Links

Authors: Josh B. Payne, Oklahoma State University and John Lawrence, Iowa State University

Reviewers: Ray Massey, University of Missouri and Kelsi Bracmort, NRCS

Business Arrangements for Manure Offsite Transfer

Why Are Business Agreements Important?

Regardless of whether manure will be land applied for crop production, composted for use in nurseries, or used to generate methane, if the manure moves out of the business where it was produced, a business arrangement has been used. Business arrangements need two willing participants, a way that they can meet, agreed on terms and price, and a document spelling out expectations and responsibilities.

Local Arrangements for Manure Marketing

Often the manure producer will merchandise manure locally by contacting crop producing neighbors that need a source of nutrients. Even among neighbors it is important to get the agreement in writing to assure that both parties understand the responsibilities, application rates and manure price. This sample form for a manure agreement provide a framework for negotiations between buyers and sellers of manure. In addition to negotiating application rates and prices, it is also important for the livestock producer to secure the land for manure application as part of his/her manure management plan. An easement is a tool for legally securing land for manure application. The easement defines the rights and terms of the agreement and it “goes with the land” such that if the land is sold, the livestock producer still has a right to apply manure to the land. Here are two publications about manure easements and agreements.

Marketing Manure Over a Larger Area

If the local supply and demand for nutrients are such that the manure producer needs to consider a broader geographic area he may then look to other methods of reaching manure buyers. These methods may include brokerage services or market finder services. Manure brokerage services are fairly common in poultry sectors because firms often specialize in litter removal and bedding replacement as a service to the building owner. These firms then merchandise the litter to land owners or tenants as fertilizer and/or soil amendment. Some states or regions are also establishing market finder websites for manure buyers and sellers. Brokers are often frequent users of these sites, but not exclusively. Examples include:

If regions have a manure surplus and manure must be transported further it is often necessary to reduce the moisture of the manure to reduce transport costs. One program, the Texas Commission on Environmental Quality, offers a Composted Manure Incentive Project.

The EPA and USDA are encouraging market based incentive programs to help improve water quality in agriculture by developing a Water Quality Credit Trading Agreement. EPA has a website with information about water quality trading, FAQs, and a map of existing programs and an online presentation. One example of environmental credit trading is in the Chesapeake Bay region including an example of nutrient trading for agriculture.

Nutrient trading programs are complex and must involve parties with excess nutrients and individuals that can make environmental improvements at lower cost than the excess nutrient parties. However, if well functioning markets for nutrients do not remove enough nutrients from a watershed, water quality trading credits may be a viable option. Often the value of manure nutrients as fertilizer is a sufficient incentive to encourage offsite movement of manure. It may be necessary to help fledgling markets evolve by getting buyers and sellers together, but typically profit minded farmers or service providers will put manure where it has the greatest economic value.

Page authors: John D. Lawrence, Iowa State University, and Raymond E. Massey, University of Missouri

Page reviewers: Kelly Zering, North Carolina State University and Josh B. Payne, Oklahoma State University