Calculations and Specifications

Row and tree/vine crop dispensers

You need to know how much carrier material will be used per acre with our dispensers. Most of our products use a 1/4" thick metering plate with a 3/8" hole, which yields a 0.45 ml quantity of material dispensed per cycle. Our 12 volt tractor and ATV-mounted products operate at approximately one cycle per second and use two metering holes (either front and back, or side by side). With this information we can determine how much material will be dispensed over time. From the table below, find your row crop spacing and then select the planned tractor (or ATV) driving speed. The numbers in the table represent the quantity of vermiculite that will be used per acre. If you use corn grit or other product, the quantities indicated here will be close, but not exactly what you need. You will need to calibrate the dispenser to determine the difference.

The table is large, because it contains row spacing from under four feet up to thirty six feet. For ease of access, the table is broken up into five parts as follows:

Row spacing up to 8'

Row spacing of 9-15'

  Row spacing of 16-22'

  Row spacing of 23-29'

  Row spacing of 30-36'

Spot-treatment dispensers

Our spot-treatment dispensers will meter approximately 0.45 ml of material with each cycle. The operator controls the cycling with these products, so that the quantity of vermiculite used needs to be based on the quantity of beneficial organisms desired to be dispensed per pulse. For example, suppose that two predatory mites are required (or average) per treatment cycle. In this case the pint bottle would contain approximately 2500 mites. In other words, the bottle will provide material for up to 1224 treatment cycles (at 0.45 ml per cycle).

Formulas

If you change the metering plate used in your equipment you will then need to calibrate your device in order to determine the quantity of carrier material that is dispensed. Here are formulas that you might need. Please remember that the formulas provide a theoretical value which needs to be reconciled with your calibration. A ten percent difference between the theoretical and actual values is not unusual.

volume of metering hole = 3.1416 * radius of hole * radius of hole
                                             * thickness of metering plate

If you measure in inches (yielding cubic inches), then you need to convert to milliliters.

volume in ml = volume in cubic inches / 0.06102

For example, with a 1/4" (0.25") thick plate and a 3/8" (0.375") metering hole, the volume of the metering hole is:

volume in ml = 3.1416 * (0.375/2) * (0.375/2) * 0.25 / 0.06102
                    = 0.453 ml

The quantity of carrier material used in row or tree/vine crops is calculated as follows:

quantity of      = (43560 square feet per acre vermiculite / row spacing in feet)
                            * (ml of material per hole per pulse
                            * number of holes in plate
                            * number of seconds per pulse)
                            / (5280 feet per mile 
                            * tractor speed in miles per hour
                            / 3600 seconds per hour)

Illustrating by example, assume that we have 10 foot row spacing, 0.45 ml of material per metering hole, 2 metering holes, 1 second per pulse, and a tractor moving at 3 miles per hour. The calculations are:

quantity of = (43560/10)*(0.45*2*1)/(5280*3/3600) = 891 ml vermiculite

This can be verified from the chart (using the link) above to be the correct quantity of vermiculite used. If you need help, let us know.

Quantity of Vermiculite Per Acre (milliliters)

Row Spacing: up to 8 feet

Quantity of Vermiculite Per Acre (milliliters)

Row Spacing: 9-15 feet

Quantity of Vermiculite Per Acre (milliliters)

Row Spacing: 16-22 feet

Quantity of Vermiculite Per Acre (milliliters)

Row Spacing: 23-29 feet