ENVIRONMENTAL EDUCATION SERIES
ENVIRONMENTAL QUALITY
Agriculture & Natural Resources
EXTENSION ENVIRONMENTAL EDUCATION, AUBURN UNIVERSITY, AL 36849-5647
Calibrating Spreaders for the Application of Animal and Poultry Manure
Circular 11/90-006. By Charles B. Ogburn, Extension Agricultural Engineer (Retired), Agriculture, Auburn University, James O. Donald, Extension Agricultural Engineer, Agriculture, Auburn University
Animal and poultry manure cannot be utilized effectively if you do not know how much you are applying to a given area. Calibrating your spreader is a simple and effective way for you to improve the utilization of the nutrients in the manure. Only by knowing the application rate of your spreader can you correctly apply manure to correspond to crop needs.

Calibration of Solid Manure Spreaders

 In order to calibrate a spreader for solid (20% or more solids) manure, the following materials are needed:

  1. Bucket
  2. Plastic sheet, tarp, or old bedsheet (an even size, 8 ft. x 8 ft., 10 ft. x 10 ft., 10 ft. x 12 ft., etc., will make calculation easier)
  3. Scales
To calibrate your spreader:
  1. Locate a large and reasonably smooth, flat area where manure can be applied.
  2. Spread the plastic sheet, tarp, or bedsheet smoothly and evenly on the surface of the test field.
  3. Start driving the spreader at the normal application speed toward the sheet spread on the ground, allowing the manure to begin leaving the spreader at an even, normal rate.
  4. Drive over the sheet at the normal application speed while continuing to apply manure.
  5. Collect all manure spread on the sheet and pour it into the bucket.
  6. Weigh bucket with manure, then subtract empty-bucket weight. This will give you the pounds of manure applied to the sheet.
  7. Repeat the procedure three times to get a reliable average.
  8. Determine average weight of the three manure applications.
  9. Refer to the chart in Table 1 for size of the sheet and pounds of manure applied to the sheet. Then read "Tons of Manure Applied Per Acre."
If the size of your sheet is not listed, the following equation may be used to determine litter application per acre.
 
Lbs of manure collected over sheet x 21.78
Area of sheet, sq. ft.		      =     Tons/acre

This procedure is particularly suitable for dry waste such as broiler and turkey litter. Wet litter or manure is more difficult, but the basic procedure can still be used. A plastic sheet works well, with the main difference in procedure being that the sheet and the litter can be placed in the bucket together, and the dry weight of both bucket and sheet subtracted as in Step 6. The remaining steps are the same.

 Calibration of liquid Manure

The application rate for a liquid waste spreader can be determined by knowing: 1) the capacity of the tank in gallons; 2) the distance the spreader travels to empty the tank; and 3) the path width over which the waste is being spread. The path width can be paced off or measured with a tape. Determining the travel distance can be more difficult. One method is to measure and count the number of wheel rotations. Measure the tire from one side to the other. This is the tire's diameter. Multiply the diameter by 3.14 to determine the distance the spreader will travel in one tire rotation. Tie a piece of rope at the top of the tire, and as the spreader moves through the field count the number of times the rope comes to the top of the tire until the tank is empty.
 
 

Multiply this number by the length of one revolution to determine the total travel distance. The waste application rate is equal to: Tank capacity (gallons)
Travel distance (ft.) x Spreading width (ft.)		 x 43,560 ft.
Acre		      =  Application rate
in gallons per acre

Table 1. Calibrating of Manure Spreaders

 --------------------Size of Plastic Sheet--------------------
Pounds of Manure
Applied to Sheet		 8' X 8' 10' X 10' 10' X 12'
----------Tons of Manure Applied per Acre----------
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22		 0.34
0.68
1.02
1.36
1.70
2.04
2.38
2.72
3.06
3.40
3.74
4.08
4.42
4.76
5.10
5.45
5.79
6.13
6.47
6.18
7.15
7.49		 0.22
0.44
0.65
0.87
1.09
1.31
1.52
1.74
1.96
2.18
2.40
2.61
2.83
3.05
3.27
3.48
3.70
3.92
4.14
4.36
4.57
4.79		 0.18
0.36
0.54
0.73
0.91
1.09
1.27
1.45
1.63
1.82
2.00
2.18
2.36
2.54
2.72
2.90
3.09
3.27
3.45
3.63
3.81
3.99

Table 2. Estimating Manure Spreader Capacity

Spreader Size
(bushels)		 Approximate Tons
of Manure
70 -  75
90 - 100
125 - 125
180		 1.5
2.0
2.5
3.5

This circular was adapted from a publication prepared by Eldridge R Collins, Jr., Extension Agricultural Engineer, Virginia Tech., Blacksburg, Virginia, entitled "Calibration of Manure Spreaders."
For more information, call your county Extension office. Look in your telephone directory under your county's name to find the number.
Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability. 

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