2005-03-02 / Farm & Home

Ag Line: Spraying solutions other than water

By Lannie L. Lanier
County Extension Coordinator

By Lannie L. Lanier
County Extension Coordinator


Sometimes we get calls from people who are trying to calibrate sprayers for the application of materials other than water. While most of the time water is the carrier, we often see liquid nitrogen or other fluid fertilizers being sprayed on. With some of these materials, you can add a herbicide and kill weeds while you fertilize. This is very common on small grains at this time of the year.

Quite often, sprayer manufacturers provide charts with new equipment that tell you the application rates at various settings for different liquids. Usually these charts get lost long before you need to look something up. Today I will give a few tips on how to calibrate a sprayer for spraying materials other than water.

The first step in this process is to determine how much a gallon of your liquid weighs. Water weighs 8.34 pounds per gallon and has a specific gravity of 1.0. Liquid nitrogen solutions weigh about 11 pounds per gallon and have a specific gravity of about 1.3. After all the math is done, the difference in volume pumped when you compare water to a nitrogen solution is about 13 to 15 percent. This means that if your sprayer puts out 20 gallons per acre of water, you can expect it to apply 17.5 gallons of nitrogen solution. This number of gallons per acre multiplied by the weight per gallon, multiplied by the percentage nitrogen will give you amount of nitrogen per acre.

The number of gallons per acre will be helpful to calculate the number of acres you can cover on one tank. This will help you determine how much herbicide to add to give the correct rate per acre.

This process is not difficult to master if you understand the conversion factor between water and your fertilizer solution. Please call if you have questions.

High Fertilizer Prices

On the average, fertilizer prices are up about 40% over last year. A lot of factors are involved, mainly high fuel costs, limited availability, and high international demand for certain products. The bottom line is that you will pay more for fertilizer this year.

A lot of farmers are looking at alternative fertilizer sources. One that comes to mind first is chicken litter. Good quality and well-handled chicken litter can contain 60 pounds nitrogen, 60 pounds phosphorous, and 40 pounds potassium per ton. If the litter is old and weathered, it will contain a lot less.

How much should you use? This varies by crop but generally two tons per acre is a good rate on most crops, especially cotton. You can use more on forage crops like coastal bermuda hay where up to six tons per acre per year can be applied. But at these rates, you need to have an economical source of litter to make it affordable. Chicken litter is not recommended for peanuts because you don’t need the extra nitrogen it supplies. Take the money you would spend on chicken litter and buy lime or landplaster instead.

Chicken litter varies a great deal in nutrient content. Layer litter is different than broiler litter. The moisture content also makes a difference. In order to know what you are applying, you need to see an analysis. If you are buying litter, ask to see the latest report your supplier has. If you have access to litter and need to know its nutrient content, we can help you get it tested. The state legislature has appropriated funds for poultry producers to get litter tested for free through the Extension Service. We will need about one pint of material in a zip lock plastic bag. There is no charge for the analysis, but we will need $2 per sample for postage. This is a great deal that you need to take advantage of if you need it.

The University of Georgia Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.


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