You may be tempted to buy alternative fertilizers during this latest rise in fertilizer costs. But before you pull out your wallet, pencil out how the costs of these products compare to the price of conventional fertilizers. Otherwise, you may end up spending more than you expected.

The true cost. For years, salespeople have pitched the merits of alternative fertilizers, claiming better pricing, higher yields and better soil stimulation than conventional fertilizers deliver. These products go by a number of names, such as soil wetting agents, organic plant food and soil conditioners.

These products do no agronomic harm. Yet, there's a catch. They may be a perfectly good fertilizer material, but when you compare prices to other fertilizer products, they're expensive on a pound of plant food basis, says Jim Gerwing, South Dakota State University extension soil scientist.

If the high fertilizer prices of the last few months make your pulse race, the cost of alternative fertilizers can put it into overdrive. In our example, an alternative product, 34-4-4-4, costs nearly 12 times as much as a conventional fertilizer, 18-46-0 (see box).

Product marketers often sell these substances in small increments. If you think $400/ton is a high price to pay for anhydrous ammonia, consider the 34-4-4-4 in our example. Sold in 50-lb. increments at $55, the product's per-ton cost is $2,200.

That's why they sell it in 50-lb. units, Gerwing says. It masks the true cost.

Farmers who already face tight fertilizer budgets may not be able to properly fertilize their fields if they buy these expensive products, Gerwing says. Thus, these products harm farmers twice: first with excessive fertilizer costs and again with lower yields.

Red flags. One way you can protect your bank account is to be aware of red flag phrases that these salespeople may use.

They'll often say, We don't know why it works, it just does, says Robert Hoeft, University of Illinois extension soil scientist. They'll also say that the product either replaces fertilizer and costs less, or is a natural product without strong acids.

Microorganism stimulation is another buzzword that these sellers use. Microorganisms do some wonderful things for us, but most of them are out there in the soil working for us already, Hoeft says.

Promoters will also tout the superior plant availability of nontraditional fertilizers. They'll say their fertilizer is 100% available to the plant, Gerwing says.

That's true. Yet, less expensive conventional fertilizers such as 28% N or 7-21-7 also are 100% available to plants.

By law, fertilizers have to be 100% available, Gerwing explains. Otherwise, nutrients can't be claimed in the analysis.

Low in salt is another familiar claim that's sometimes true, Gerwing says. However, this statement isn't as positive as it sounds, because salt is a fertilizer nutrient. Materials that have less salt in them also normally have less fertilizer value, Gerwing says.

Sellers also promote low rates. Oftentimes, they recommend low rates, such as about one-fourth as much as conventional fertilizer, Gerwing says. If you need more nutrients, though, you will reduce your yields.

What makes these products so difficult to resist is that they are often sold through sources other than fertilizer dealers.

Many times, farmers buy these products from neighbors, friends and relatives, Gerwing says. Often when people buy these things, they'll say, I'm kind of skeptical, but I bought it from someone I know. It's difficult to say no to the guy down the road, or the guy that you see at church. So, they'll buy a small amount as a social kind of thing.

What can you do? Maybe you're a nice guy who doesn't mind parting with your hard-earned dollars. Then again, the money that you spend on these products could buy much more conventional fertilizer to cover your acres. If salespeople pitch you these products, follow this advice that we rounded up from extension soil specialists.

Ask for research data. Sellers of alternative products often show company data to support their claims. If you ask them for unbiased research information, one of their comments is that universities wanted us to pay them money, and we aren't going to do that, Hoeft says.

Data should be from multiple years and multiple locations. Data from just one site or replication can be misleading, says John Sawyer, an Iowa State University extension soil scientist.

You have to take the time to obtain multiple sources of information to make an informed decision, Sawyer says.

Walk away from high-pressure tactics. Some of these folks will want you to buy the product before you have time to verify its worth. Don't buy on the spot until you've had some time to check it out, says David Whitney, Kansas State University extension soil specialist. Ask questions and call others to see if what they're saying is right. Try to discern what the active ingredients are, and if the rate they recommend really works. If the salesmen say the price will change if you take time to check it out, so be it. Don't let the hype get to you.

To help you decide, soil scientists in the north-central region have compiled reports about many alternative products. Compendium of research reports on use of non-traditional materials for crop production is available from Iowa State University Extension Distribution Center. The compendium costs $10 and its two supplements cost $3 and $7, respectively. Shipping is $6.38 extra. To order, call 515/294-5247, fax 515/294-2945 or e-mail pubdist@iastate.edu.

Test it on your farm. If everything looks okay, you can still learn more by testing the product on a small portion of your farm, says Keith Kelling, University of Wisconsin extension soil specialist.

If you're satisfied that the program is doing what you want it to do, good, Kelling says. At least you have a real basis for comparison.

Although it's good to be open-minded, retain a healthy dose of skepticism about these products, Sawyer says.

Do your homework and find out what multiple people, including researchers and crop advisers, say about these products, Sawyer says. The main thing to remember is that if it sounds too good to be true, it probably is.

Cost comparison

Nontraditional fertilizer

Analysis: 34-4-4-4

Percentage of nutrients contained in fertilizer: 46%

Product amount: 50 lbs.

Price: $55

Price per pound of plant food:
Multiply nutrient percentage by total amount: .46 50 = 23 lbs.
Divide price by total amount of nutrients: $55 23 = $2.39/lb. of plant food

Conventional fertilizer

Analysis: 18-46-0 (diammonium phosphate)

Percentage of nutrients contained in fertilizer: 64%

Product amount: 50 lbs.

Price: $6.50 (based on $260/ton price)

Price per pound of plant food:
Multiply nutrient percentage by total pounds of material: .64 50 = 32 lbs.
Divide price by total amount of nutrients: $6.50 32 = $0.20/lb. of plant food

Example courtesy of Jim Gerwing, South Dakota State University extension soil scientist, and John Sawyer, Iowa State University extension soil fertility specialist