Weary of visiting farmlands with depleted fertility, specialists with the University of Arkansas are warning farmers not to rely on liquid fertilizer supplements to keep fields healthy and yields high. Any claims to the contrary should be carefully scrutinized.
“There’s nothing wrong with selling a supplement if it’s for the correct purpose,” says Rick Cartwright, university professor and Extension plant pathologist. “But there’s plenty wrong with convincing farmers to use it in place of a proven fertilizer program.
“Over the last five years, I’ve seen farms and farm families ruined by such things, and I’m tired of it. Some of the farmers are no longer in business and others are in a mighty struggle to survive because they bought into these sales pitches.
“I understand selling registered fertilizers is legal. And I understand that many of the claims made to farmers are at the tailgate and not on paper. But you know what? We need to put a stop to it. It’s hurting our farmers. I’m tired of seeing my friends suckered by smooth-talking guys.”
If you pick up a fertility textbook and look up potassium’s function in plant nutrition and growth, one thing hammered home is the nutrient plays a vital role in a plant’s ability to resist stress and diseases. Many times when Cartwright is called to fields heavily infested with disease, there appears to be a consistent link between the disease severity and potassium available to the crop.
That finding is nothing new, “but it’s something that we need to be reminded of,” says Nathan Slaton, associate professor and fertility specialist. “It’s often overlooked — especially nowadays when we’ve been farming these soils for years. The yield potential of varieties and the entire management package has increased due to irrigation, better cultivars, etc. Simply put, there’s an increasing strain on the soil’s ability to adequately supply these nutrients in the absence of adequate fertilization.”
One big factor in the surge of dubious products is the escalating cost of fertilizer.
“A lot of that has to do with fuel prices. When fuel went from $1.80 per gallon to $3 per gallon, that meant more for transporting the fertilizer; it costs more to mine or manufacture it, on down the line. So all fertilizer prices have gone up.”
Since late September, the most common questions Slaton has heard have to do with rumored price increases for fertilizer again next year. For that reason, “some fertilizer dealers suggest farmers fall-apply nutrients. Whether that’s a good idea, or not, is another issue. But that is happening.”
With the exception of soybeans, any crop that’s grown on silt and sandy loam soils needs nitrogen and most of those soils in Arkansas also require phosphorus and potassium.
“Those things are needed if, for no other reason, than to just maintain current fertility levels. And in a lot of those soils, the crop must be supplied a portion of its nutrient requirements in order for it to reach its yield potential.”
University recommendations are based on standard, granular fertilizers.
“We can calculate how much nutrient is removed in a certain yield. The total nutrient removal — outside a crop like hay — by the harvested portion of the crop is always less than the total uptake of the crop. So 99.9 percent of the work we do with P and K is based on soil applications of muriate potash, Triple Super Phosphate — those types of fertilizers.”
Regardless, the controversial fertilization “schemes” are pushing liquid supplements. The liquids are more expensive than the granulars because they’re refined and, generally, of a bit different chemistry. To be able to compete economically, the products’ rates of application are lowered.
If a farmer is growing 60-bushel, or higher, soybean yields, 80 to 100 pounds of K2O fertilizer can be removed. The field will need 140-plus pounds of muriate potash just to replace the potassium removed by that crop.
Some of the fertilizer schemes are pushing rates far below that. That leads to a situation akin to “a fat man and a skinny man on a teeter-totter. There’s no balance. If the crop is removing more nutrients from the soil than what’s being added, over time what will happen? Inevitably, the field will have nutrient deficiencies.”
Potassium, for some reason, seems to be the favorite nutrient used in the fertilization schemes, says Slaton. “Some of them push foliar applications, suggesting that’s a more efficient method of uptake. In some cases, there may be some truth to that. Most of the claims made for these schemes aren’t flat-out untruths. They’re taking some truth and twisting it.
“One company has been telling farmers ‘there’s enough potassium in the soil to grow crops for 100 years.’ And that’s actually true. Unfortunately, 98 percent of the potassium in the soil isn’t in a form that can be taken up by the plant. That’s the kind of thing we’re dealing with.”
With nitrogen, the major nutrient applied in Arkansas row crops, “we simply haven’t found a form better than urea, ammonium sulfate or ammonium nitrate,” says Rick Norman, University of Arkansas professor in soil fertility. “There aren’t any better products than those.”
One of the additives researchers have found beneficial to urea is Agrotain. “It stabilizes urea, and we recommend it. Because of its success, many copycat products have come out claiming equivalence with Agrotain. But they aren’t. When it comes to fertilizing, farmers need to use the common, tried-and-true fertilizers the universities recommend.”
As for P and K, “we’ve found no additives that will help with uptake,” says Norman. “At best, the suggested additives have worked inconsistently or, at worst, show no benefit at all.”
Companies selling the supplements often tell farmers “the products they’re selling are taken up by plants much more efficiently than standard fertilizer.”
As an example, Norman points to urea in rice. “They say urea in rice is taken up very inefficiently and their product is four to 10 times better, or whatever. As a matter of fact, rice takes up urea very efficiently when standard recommendations are followed. Sixty to 70 percent of pre-flood nitrogen gets into the plant. And another 70 to 80 percent of the mid-season nitrogen is taken up.
“The product salesmen usually target the mid-season urea application. Where we recommend 45 units, they claim the farmer needs only 10 pounds of their fertilizer product. Well, bull.”
There is “no question” long-term effects of those claims are hurting yields, says Norman. “The companies will claim they’ve come upon a new formulation of nitrogen, a complicated form that can be taken up through the leaves. But major nutrients can’t be taken into the plant in enough volume through the leaves. That’s why we fertilize the soil.”
Only micronutrients can be taken on board through the leaves in adequate amounts. The reason: the plants only need a small amount per acre.
“If you applied the required amounts of the major nutrients N, P and K to the plant foliar instead of to the soil, you’d need many multiple applications during the season of a very diluted liquid fertilizer. And you’d probably still damage the leaves severely and kill the crop, no matter what chemical formulation was utilized.
“That’s why companies recommend low rates and claim enhanced efficiency compared to standard soil applied fertilizers: so you don’t have to apply as much fertilizer in many multiple applications and realize the real cost of trying to fertilize a crop in this fashion.”
Ebb and flow
There is an ebb and flow to the popularity of fertilizer supplements.
“Right now, it’s flowing and it’s hard to keep up,” says Norman. “We test (supplemental fertilizer) products all the time. Companies assure us they’ll do great things but we find they don’t.”
Such products pop up continuously, says Slaton. “Last spring the price of zinc fertilizer went up dramatically and company ‘miracle liquids’ came out of the woodwork.
“University recommendations call for 1 pound of zinc per acre in a foliar application. We hear, ‘With our product, you won’t have to use that much. It has a secret enzyme!’ Really? A secret enzyme?”
The wave of new products mean it’s almost impossible for university researchers to keep up and produce timely, replicated data to prove or refute company claims.
“It’s a continuous thing,” says Slaton. “Only recently have these schemes shown up big in macronutrients. The last five years or so have brought a lot of potassium schemes, especially.”
A farmer who’s been in a conventional fertility program and has fairly adequate soil fertility levels can make a switch to one of the liquid-type schemes and, for a few years, may see no effect on his crops. However, over time, as the crop continues to remove more potassium than is being applied, yields will inevitably drop.
“One of the reasons I’m so sure about this is I’ve been working potassium studies at the Pine Tree Station (near Colt, Ark.) for the last eight years, looking at long-term effects of fertilization levels. When you provide the soil insufficient rates of even granular fertilizers, over time yields will plummet. Usually those yield differences show up the fourth or fifth year.”
One thing that’s interesting in those circumstances is nutrient deficiency symptoms sometimes won’t show up until yields drag. “That’s commonly called ‘hidden hunger.’ The plants need potassium but don’t show it as yellowed leaves or heavy disease infestations. It’s a gradual thing until the crop plummets.”
One of this year’s Pine Tree potassium studies was in rice. The plots with recommended and higher rates of potassium fertilizer produced 190-bushel dry rice. The unfertilized control yielded 130 to 140 bushels.
“And we saw those effects on crop growth within two weeks after flooding. We’ve been seeing plants with sub-optimal growth, they don’t tiller as well, they don’t canopy as quickly, don’t grow as tall, and set less grain.”
Among sales pitches Slaton has heard “are those pointing out muriate potash contains chloride. And, yes, soybeans are sensitive to chloride and that’s often associated with salinity. The companies can play on that — ‘chloride is bad for the soils, bad for the crops and by using our product instead of muriate potash, you’ll be better off in the long run.’”
In the short term, the product may appear equal and the farmer will make the switch.
“When a farmer is saying, ‘I’m using this stuff and it works,’ what can I say? In our research, we haven’t had time to study some of these fertilization schemes alongside standard recommendations,” says Slaton. “It’s hard to argue short-term.”
Long-term, it’s much easier. In the lengthy potassium study, Slaton has found stem rot “absolutely ravaging unfertilized controls. The plots that haven’t received potassium fertilizer in eight years are being torn apart by disease.
“With something like potassium, it’s hard to tell where all the yield loss is coming from. Are losses all nutritional? Or, are the yield losses due to both nutrition and disease damage?
“It’s kind of like a dog chasing its tail. If you don’t put the K out, you feed the disease. But then you buy fungicides to knock the disease out. Well, how much of the fungicide could be cut out with just an adequate fertility program?”
The controversial liquid fertilizers are, for the most part, temporary supplements. The researchers insist they mustn’t be used as a substitute for a complete, fundamental fertilization program. Those fundamentals should be based on individual situations that are determined by routine, consistent soil tests.
“As a plant pathologist, my interest is in helping farmers develop and manage healthy plants,” says Cartwright. “Healthy plants have high yield potential. Unhealthy plants have low yield potential and high disease potential and are much more difficult to manage. Healthy plants that are jumped by disease are much easier to help than those stressed for nutrients.
“Where these foliar supplements have been used too much and salesmen have sold them in an inappropriate manner, many problems develop. I have seen this repeatedly.”
Over time, a corn farmer using only the supplemental liquids will often lead his crop to stalk-rotting diseases. The diseases will “go after the bottom of the plant and kill it before it can set a good yield. Farmers will harvest dead plants with tiny ears and cut 100-bushel corn instead of 200 bushels. Improperly used fertilizer supplements can cost farmers a lot of money on the back end.
“In the long-term, using these dubious fertilizers will ruin soils. Quote me on that: they will ruin your farm. When that happens, it’s very difficult to build the fertility back up. Once you’ve fallen off the cliff with P or K, it’s hard to bring the soil back. Nitrogen isn’t as difficult to build back up.”
To be blunt, says Cartwright, “What we have in this state are companies selling products that are unproven for what they claim. It’s one thing to use them as a supplement, for them to be used for a minor need. It’s another thing for a salesman to claim 2 gallons of his product is equal to 100 pounds of urea. That isn’t possible, no matter how insistent they are. There is no way 2 gallons of a liquid that’s mostly water and contains 5.2 pounds, or so, of N is equal to 100 pounds of urea that contains 46 pounds of N. You honestly want to claim that?”
One central Arkansas Extension agent says in recent years he frequently spoke with farmers who have been subject to “a hard sell on these supplements. There are people actually claiming their products are so super you can (eschew) Extension fertilizer recommendations.
“If you’re a grower looking at such high urea prices, you really want to believe. ‘Well, this can’t be untrue. I’ll give it a shot.’
“This year, grain prices have been good, so some products, I think, were bought and applied unnecessarily. I just wish these products hadn’t been pushed this way. The data needs to be stronger and justified before farmers are told these products are so good. I don’t like it when someone leads his neighbor to spend money unwisely.”
Smart, clever, suckered
It doesn’t matter how smart and clever you are, you can still be fooled.
“Everyone gets taken for a ride,” says Norman. “I certainly have been. Most people are honest and so they want to believe others. And if the story is good, we want to believe it even more.”
Norman admits he would like to find miracle products. He’s looking hard. “We’re always looking for a silver bullet. We want to help agriculture — the farmer, the distributor, the maker. New technologies and products can benefit all. You think I wouldn’t be recommending a product that’s actually four to five times better at uptake than standard fertilizer? Gosh, that would be something to celebrate, something to shout from the rooftops!”