When broadcasting manure, a number of variables affect the unloading speed and spread pattern produced by your tanker:
Manure viscosity can differ drastically from one pit to another—even during the discharge of a single pit. Thicker manure unloads more slowly and usually produces a narrower spread band. Unloading time and spread width has to be checked more often.
Impeller blade: Jamesway offer 5 different models, ranging from very low-flow (for use with injectors) up to high-flow blades for fast unloading at high ground speed.
Minor changes in PTO speed will vary both the flow rate and the width of coverage.
Spreading plate: Jamesway offer 3 orifice sizes; 3.75, 5 or 6” outlet. Matching the spreading plate to the impeller flow produces a high quality spread pattern with even coverage.
Position of spreading plate (high or low mounted): High mounting covers a wider area than low mounting but is more prone to wind drift.
Tankers equipped with a flowmeter and GPS are extremely precise at applying manure at the desired rate, but this technology is expensive. Fortunately, spread pattern and the rate of unloading are constant when operating at a steady PTO speed—regardless of the equipment set up you use. Essentially, the speed you drive determines the amount of manure applied per acre.
Using only a watch and tape measure, Jamesway’s new Tanker Calibration Calculator makes it easy for operators to calibrate the rate of application. Simply measure the time it takes to spread a full tanker load while running at typical PTO speed and measure the width of the spread pattern. With this information, you’re now ready to use the calibration calculator—available in both metric and imperial measurements.
Enter the tanker capacity and desired application rate, together with the spreading width and unloading time. The calculator will then work out the following information for you:
Here’s an example, using a Jamesway 7,400 U.S. gallon Ultra-Trac tanker: You measured the spread width at 45 feet, and it took 3 mins. 15 secs. to empty the load. If you want to apply 6,000 gal/acre, the calculator works out that you need to drive at 4.2 MPH. If you change the desired application rate to 8,000 gal/acre, the calculator adjusts the required speed to 3.15 MPH.