Submitted by Brandy Brabham
WVU Extension Agent
Even though the prices of most fertilizers are much lower now than they were this time last year, farmers are always looking for a bargain. This is the exact time to be cautious about claims that seem too good to be true.
To protect producers, several laws and regulations are in place through the West Virginia Department of Agriculture. All brands and grades of fertilizer, lime and soil/plant amendment products must be registered before they can be sold in the state.
Before you buy, evaluate whether what you are being sold is real or bogus. Follow these steps recommended by Ohio State University's Robert Mullen, soil fertility specialist, and Edwin Lentz, Extension educator.
Think Before You Buy
If it sounds too good to be true, it probably is. This old adage is almost always true. So if a product is promising tremendous yield improvements by supplying adequate nutrition, suppressing weeds, and improving soil health via a small application rate, it is most likely not going to deliver the desired benefits.
Take a lesson from the first law of thermodynamics. That law states that energy can neither be created nor destroyed - it simply changes form. Therefore, nutrients can neither be created nor destroyed; they can only be shuttled between different pools.
So, if the product label states that application of the material is equal to 50 pounds of phosphorus per acre, if the material fertilizer analysis (required on the bag by law) has 20 percent phosphorus and if the application rate is not 250 pounds per acre, you can not supply the same amount of nutrients at a rate of 50 pounds per acre. The maximum efficiency of any system is 100 percent. So how can this product magically supply more than is being applied?
Look for unbiased research results. Many products are vetted through land-grant universities to determine their potential usefulness. Just because a product works at some remote location does not necessarily mean it will work on your farm. (That is why land-grant universities conduct field research.) If the individual selling you the product is also the individual conducting the research, be wary.
Start small. Before completely adopting an alternative product on your entire farm, evaluate the product on a limited basis and make simple comparisons to current practices. If you see no yield advantages, you have your answer.
Consider This
Liquid formulations are not used throughout West Virginia. A liquid fertilizer material being promoted in parts of the state provides a good example of the questions producers need to consider this spring.
Here's some helpful background from the Penn State Agronomy Guide: "The bottom line in comparing fluid fertilizers with dry fertilizers on the basis of amount of plant food, is that they are equal in agronomic effectiveness when each is used properly. Remember, when making calculations of fluid fertilizers, that the analysis is given as a weight percentage, not on a volume or 'per-gallon' basis. Most fluids weigh between 10 and 12 pounds per gallon."
Consider that a recommendation for nitrogen application in the spring is 50 pounds per acre. Imagine that the liquid fertilizer material a farmer is considering states it has an 8-16-8 analysis. For every 100 pounds of material applied per acre, the field would receive 8 pounds of nitrogen, 16 pounds of phosphorous and 8 pounds of potassium.
If the estimated weight of each gallon is approximately 11 pounds, to apply 8 pounds of nitrogen the farmer would have to apply 9 gallons of the material per acre. If the material costs $50 per gallon, it would cost the user $450 per acre to only apply 8 pounds of nitrogen, 16 pounds of phosphorous and 8 pounds of potassium.
To make an application of 50 pounds of nitrogen per acre, the user would have to apply 56.25 gallons at a cost of $2,812.50. Using this liquid material, the farmer would have applied 50 pounds of nitrogen, 100 pounds of phosphorous and 50 pounds of potassium. The label on this material recommends using 24 ounces (.19 gallons) per acre in 15 gallons of water. Following these directions, the farmer would apply .2 pounds of nitrogen, .4 pounds of phosphorous and .2 pounds of potassium per acre.
A producer has several ways to reach the goal of 50 pounds of nitrogen. The most efficient way is to use Urea (47-0-0), which requires just over 100 pounds per acreâor approximately $22 per acre. (Use this material early in the morning or late in the evening, preferably before a rain to reduce volatilization.)
To achieve 50 pounds of nitrogen with 10-20-20 fertilizer, a producer must apply 500 pounds per acre at a cost of $157.25. The applicator would not only get 50 pounds of nitrogen but also 100 pounds of phosphorous and 100 pounds of potassium, whether it is needed or not.
Following these simple rules can help you separate good products from bad.
Also remember that soil testing through the West Virginia University Soil Testing Laboratory every three years can provide you with an accurate measure of fertility needs.
Consult your local WVU Extension office if you have any questions about fertilization of pastures, meadows, cropland, gardens or lawns at 304-927-0975 in Roane County and 304-354-6332 in Calhoun County.
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