Do you have a flow meter, but are not sure how to use it to apply the specific amount of nitrogen from lagoon water called for by your nutrient management plan? Check out this new Excel spreadsheet from the University of California Cooperative extension for help.

The tool allows users to easily calculate the flow rate or run time needed to apply just the right amount of lagoon nutrients using your flow meter and throttling valve.

To use the spreadsheet, simply enter the acres and expected irrigation run time for each field, choose a reasonable expected lagoon concentration from a list and the program will generate a data sheet with the needed gallons per minute or lagoon pump run time for each field, explains Marsha Campbell Mathews, University of California extension farm advisor for Stanislaus County.  Actual start and stop times, meter totalizer readings and weather data are recorded as well.

You can print out this sheet and give it to your irrigator so they can adjust the throttling valve for each field according to the instructions.

If you don’t have a flow meter, a similar spreadsheet calculates how long to run the lagoon pump on each field or check to apply the amount your plan calls for.

Access the spreadsheet here. From the left menu, choose “Applying Target Rates of Lagoon Water Nitrogen”, then follow the link for either the flow meter or flow rate method. Follow the links on those pages to select the computer spreadsheet option.

Resources for hand calculations or tables for targeting nitrogen applications are also available on this page.

Contact Matthews at: for more information.

Source: “Stanislaus Forage Farmer”