January 29, 2020

Calibrating Liquid Manure Application

With drag hose application, there are a lot of different factors and conditions that affect the application rate out in the field – such as tractor speed, operating pressure, friction loss from hoses, etc. By calibrating your equipment, you’ll be able to better match the application rate to the nutrient requirements of the field’s pre-determined Nutrient Management Plan. This will help you avoid misapplication issues that are brought on by under and over application. 

Proper calibration of drag hose equipment requires the measurement of tractor speed, spread width, and flow rate through the hose. Many drag hose systems – such as Puck Enterprises’ Swing Arms – incorporate the use of flow meters to present an accurate measurement of liquid flow rates while in the field. Once you have those three measurements, you can determine the desired ground speed or desired application rate for a job. Below are a few calibration formulas that can be used to figure out the optimal ground speed, needed application rate, and optimal flow rate.

Calculating Desired Ground Speed

Ground speed plays a big part in the application rate. The faster you go, the lower the application rate. To achieve a higher application rate, you decrease speed. The following formula will assist you in determining the preferred ground speed when the application rate is known. 

For example: An applicator uses a 25FT wide Puck Toolbar. The applicator measures a flow rate of 3,000 gallons per minute and wants to apply manure at a rate of 15,000 gallons per acre. With those three values, what would be the needed ground speed?

Calculating Proper Application Rate

These values can be used to figure and check the necessary application rate as well. 

Example continued:

Calculating Optimized Flow Rate for Maximized Time 

If you need to check to see if your current flow is meeting the target rate, you use the following formula to figure the current flow rate. If the rate does not meet the target, adjust either the ground speed or flow to reach the ideal flow rate. 

Example continued:

With these three formulas, you’ll be able to better stay in line with the application requirements on a particular job and make adjustments to your drag hose systems while in the field. For more information about liquid manure application equipment that is built to lead, visit