Manure Spreader Calibration


To be able to manage manure on farms it is essential to know the quantity being spread.   Knowing the amount of manure spread and plant nutrients available from the manure enables an adjustment to be made to the amount of fertilizer needed. It is important to spread the manure evenly possible to avoid part of the field getting excessive nutrients and another part of the crop not getting enough.  Equally important is to spread the manure over the whole farm since the nutrients in the manure in part come from crops harvested from the whole farm. This will avoid potential accumulation of excess nutrients in fields close to the barn. 

To calibrate the manure spreader use either of the following procedures.

Spreader Calibration - Method 1

Equipment: plastic sheet 6 x 6ft or 10 x 10ft, scale, bucket

1. Weigh sheet with bucket on the scale

2. Lay sheet in field in the path of manure spreader positioning it so the tractor will be at spreading

    speed before it reaches the sheet.

3. After spreading weigh sheet and manure in the bucket.  Subtract weight of sheet plus bucket

4. Tons manure/acre = lb manure x 21.8

                                   sheet size, sq ft


Spreader Calibration - Method 2

Equipment: yard stick, rope

1. Determine manure spreader capacity

2. Tie rope around tractor tire to determine distance traveled in one revolution

3. Spread manure load, counting wheel revolutions to determine the distance traveled

4. Measure width spreader is covering with manure, multiply by distance traveled

5. Divide by 43,560 to determine acres covered by one load

6. Divide spreader capacity by acres covered to determine tons or gallons applied per acre


Stephen J. Herbert

Dept. Plant and Soil Sciences

University of Massachusetts Amherst

CDL Publ. 00-5

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Last updated: 11/11/02.