Getting Green from Brown – Fertilizer Value of Manure
Extension Educator, Crop Systems
Rockford Extension Center
Dept. of Agricultural & Biological Engineering
The increases in commercial fertilizer prices have contributed to a renewed interest in using manure as a source of crop nutrients. Determining the value of manure requires knowing: the nutrient content of the manure, nutrient requirements of the crop(s), soil test analysis, application rate of the manure, and environmental factors that may affect rate and timing of application. This abstract and presentation will focus on liquid swine manure.
(1) Determining the nutrient content of manure starts with obtaining a representative sample. Agitation of the manure prior to taking a sample will provide a more consistent analysis. A quart-sized plastic container with a screwon lid filled two-thirds full can be sent to a laboratory. At a minimum, the analysis should include dry matter or moisture content, total nitrogen, ammonium-nitrogen, phosphorus (P2O5), and potassium (K2O). Average analysis of liquid swine manure (based on 18 samples) from a commercial laboratory in Illinois and “book” values from Midwest Plan Service publication number MWPS-18 Section 1, “Manure Characteristics” are shown below.
|Percent Solid||Total N||Ammonium-N||P2O5||K2O|
|Lbs. per 1,000 gallons of manure|
Laboratory analysis is recommended since the actual concentration of nutrients may be considerably more or less than “book” values. Manure analysis will vary by animal species, age and stage of production, and form of manure (liquid, slurry, solid).
Laboratories that test manure are listed on the Illinois Manure Management Plan web site, https://webs.extension.uiuc.edu/immp/resources/
(2) Phosphorus and potassium maintenance level required for selected crops are shown in the following table. Nitrogen rate for corn can be determined using the N-rate calculator http://extension.agron.iastate.edu/soilfertility/ nrate.aspx
|Corn grain||0.43 lb. per bu.||0.28 lb. per bu.|
|Corn silage||2.70 lbs. per ton||7.00 lbs. per ton|
|Soybean||0.87 lb. per bu.||1.30 lbs. per bu.|
|Wheat||0.90 lb. per bu.||0.30 lb. per bu.|
|Alfalfa/grass||12.00 lbs. per ton||50.00 lbs. per ton|
(3) Fields need to be soil tested every three years as per the Illinois Livestock Management Facilities Act (LMFA). Monitoring the status of phosphorus and potassium is critical. According to LMFA, if the field average Bray P1 or Mehlich soil test is less than 300 lbs. per acre, manure can be applied based on the nitrogen need of the crop. If greater than 300 lbs. per acre, manure cannot exceed the phosphorus maintenance rate of the crop. The first priority for manure application is on lower phosphorus and potassium testing soils.
For a listing of soil testing labs, see the Illinois Soil Testing Association web site http://www.soiltesting.org/
(4) Calibrating manure spreaders enables producers to know the rate and uniformity of manure application. Methods to calibrate various types of manure application equipment are provided at this web site https://webs.extension.uiuc.edu/immp/menu/
(5) Environmental factors affecting manure application include setbacks or buffers; for example, 200 feet from surface water, one-quarter mile from non-farm residence for broadcast manure, and 150 feet from drinking wells. Other environmental factors include not applying manure in waterways, and not applying manure to frozen or snowcovered ground with land slopes of 5 percent or more unless adequate erosion control practices exist. You can find the regulations on manure application at web.extension.illinois.edu/ezregs
Adjustments in value may need to be made since the nutrients in manure will not be in the same proportion as commercial fertilizer and will not be supplied in balance with crop needs. Method of storage and application, ration composition, and the time of application also affect the value. It may be difficult to establish a value for organic matter, sulfur, iron and other components contained in manure.
The presentation will discuss establishing a “dollar value” to manure.
Sample lease agreements for manure application on land not owned or rented are provided here https://webs.extension.uiuc.edu/immp/resources/
Other web site references include: Illinois Certified Livestock Managers Training www.livestocktraining.com , EZregs – Making Sense of Illinois Agricultural and Horticultural Regulations web.extension.illinois.edu/ezregs , Midwest Plan Service www.mwps.org, and Illinois Manure Management Plan www.immp.uiuc.edu