November 2000, Volume VII, Issue 11

Liquid Lawn Fertilizers
What You Need to Know

David M. Kopec, Extension Turfgrass Specialist

Liquid lawns! Sounds pretty slippery? Well, the answer is...yes.... and no.
It all depends on how much you do know!

Liquid lawn fertilizers are really an encompassing group of products, which may encompass any of the following.

1. Nitrogen fertilizer carriers

2. Complete fertilizer carriers (contains N-P-K).

3. Iron containing products (either with or without nitrogen).

4. Bugs in a jug, or organic acid mixtures, or >carbon based= nutrients.

Nitrogen carriers in liquid form are diluted solutions of urea, and/or ammonium nitrate, and/or potassium or calcium nitrate. These forms of nitrogen are completely water soluble. [These same fertilizer products are sold as solid granules, usually much cheaper for cost per unit lb.]

Always check the label directions for application amounts and application method. Most concentrate products call for a dilution of a specific amount of product per gallons of water to be added to a sprayer. For example, a liquid fertilizer product may call for 1 pint of >Ferti-Wet= fertilizer to be mixed with 2.5 gallons of water (which is the same size as a small back pack sprayer). Simply mix the 1 pint of concentrate in the 2.5 sprayer (fill halfway and shake first), and then spray till the leaves are wet.

Complete liquid fertilizers contain any mixture of water soluble fertilizers that contain N-P-K, together. It will say on the label to apply a specific amount of the bottle concentrate, in a mixture of water. It will say usually how much of the dilution (concentrate plus water) or how much of the concentrate alone (they are leaving the dilution up to you) is to be applied to the lawn. Instructions can include either of these volumes per 100, 250 or 500 square feet of turf.

Note that in the case of liquid fertilizers, that it may take several bottles of concentrate to apply 1.0 lb. Of actual -N- per 1000 square feet of lawn. Many homeowner products are low concentration products to be on the safe side. The manufacturer does not want to have the homeowner potentially damage the lawn if the dilutions and/or applications are made incorrectly. The damage here would be foliar damage to the leaves (foliar burn)!

Iron containing products in liquid form are readily available for homeowner use. Iron sources range from insoluble iron (such as ferrous sulfite), quickly soluble but short lived forms (such as ferrous sulphate), to top off the line chelated (long lasting iron wrapped in special chemical protecting agents).

If you buy a big jug for only a few dollars, check the label. Either the concentration is low, or the source is of low solubility (ferrous sulfite type products).

Bugs in a jug are being sold to a fair amount of home lawn markets. Concentrations of organic acids (humic and/or fulvic acids, for example) are being sold to increase the degradation of lawn thatch and to increase the fertilizer holding capacity of the soils. In theory, this may be true, but you need phenomenal amounts of product over time to demonstrate any potential benefits. This is also true for adding organic based carbon compounds like sugar or molasses to the turf to feed microbes. The amount added is anywhere from 1/10,000 to 1/100,000 times required to provide enough carbon skeletons for all the soil bacteria, actinomycetes and fungi.

Any or all of the above products can be sold commercially as hose-end applicator products that reside inside a jar or cartridge. At the end of the jar or cartridge is a hose thread, and on the other side a spray outlet. Simply follow the directions on how many square feet to spray each bottle of product on the lawn. A 10'x10' square area of the lawn is equal to 100 square feet of lawn space.

Some products are refillable, in that you can install a block of fertilizer inside the cartridge or some amount of concentrate inside the jar again after it's used up. Others (such as pesticides) are sealed permanently in non-reusable canisters.

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Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

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