Non-Conventional Fertilizer Additives and Amendments

Higher commodity prices have been an incentive for the marketing of a deluge of products designed; it seems, to drain away farm income. Most of these products have at best no advantage over standard commercial products, and in some cases may cause economic losses to growers who choose to use them over less expensive standard products and programs. I have limited space, so I will confine this alert to product groups with the exception of a couple of well-publicized products of questionable value. For more information on individual products, search the web for Iowa State Compendium Non-conventional Additives. The compendium contains research from non-biased sources for a large number of products. Since new products are continually introduced and it is not possible to test them all, look for product categories. For example, if a starter fertilizer is fish/shellfish extract based, search within the compendium for ‘fish’ and a number of product experimental results will be displayed. These associated studies will provide some direction to growers and suppliers whether the new product has a reasonable chance of success. Here is a summary of product categories:

Soil conditioners: These products are generally soap-based or surfactant based. In the short term (a few days) these products may reduce surface tension and allow water to penetrate soil better. However, they appear to break down rapidly and have had no long-term seasonal effects. Careful experiments on products such as Agri-SC™ have shown no differences in soil properties following its use. These products have no effect on soil salts.

Biological nitrogen fixers:  All soils have bacteria that fix nitrogen. Clostridium and other bacteria are natural parts of all of our soils. In very controlled laboratory conditions, the amount of N that these bacteria can fix can be large. However, in soil most studies show only about 1-5 lb N/year. Environmental conditions including temperature, moisture, and perhaps natural pathogens and competitors limit their effectiveness. Adding more of these to the soil has not been helpful in field experiments.

Nitrogen-fixing signal molecules:  In legumes, there is a complicated feedback mechanism for nitrogen-fixing bacteria attraction, infection and sustenance. Some of the signal molecules sent out by legumes to attract bacteria have been isolated and are now marketed under a variety of names. In careful field experiments, these products generally have not resulted in higher yield than normally inoculated varieties. With any growth regulator, the application of a one-time stimulant ignores the elegant feedback from the plant and the interaction of bacteria and plant. Legumes will only support so much nitrogen-fixation. With our present technologies we do not seem to be able to force them to fix more.

Ortho-phosphate is better than poly-phosphate? The debate over orthopoly phosphate has raged for 40 years, since TVA developed poly-phosphate fertilizers (usually 10-34-0) in the early 1970s. Many hundreds of unbiased studies have been conducted, including many in this region. There is no difference in plant P uptake or crop yield whether a grower applies ortho or polyphosphate fertilizers. Neither is more efficient than the other. I recommend a grower uses a P fertilizer based on cost per pound of P₂O₅ and the convenience of the formulation. If your brother-in-law sells a high-priced ortho, maybe you need to buy a little to have peace at Christmas. This is the only reason I can think of to use the high-priced materials.

Phosphate inoculants: These products, including Tag-Team™ and Jumpstart™, contain a fungi that acidifies its hyphae zone (fungal root zone). If a soil has a pH well over 7 with significant carbonates, the acidification can dissolve carbonate minerals that coat P compounds and release some, perhaps as much as 10 lb P₂/O_rseason. However, if the soil has a pH of 7 or below, it has no carbonates and it has no coatings of carbonates and it does nothing to improve P nutrition. Several studies of this fungus in the region have shown that without the proper soil conditions the product does not increase P availability to crops. The company knows this is what the data shows because a representative visited with Dr. Goos and myself before they went to market and they chose to ignore us. Hmmm.

Micronutrient mixes: A large amount of micronutrient mixes are sold I think because growers and maybe some suppliers do not understand soil or plant analysis. Just because a zinc test is ‘low’ does not mean it is low for all crops. A low zinc test should compel a zinc application only on responsive crops. In North Dakota, these crops are corn, potato, flax and dry edible beans (not soybeans or other legumes). The only other micronutrients that we have found responses to in North Dakota are iron and copper. Iron responses have been recorded in sugarbeet, at Fe-ortho-ortho-EDDHA rates of about 1 lb formulation/acre. In soybeans, the rate of Fe-ortho-ortho-EDDHA should be about 2 lb formulation/acre. Both of these applications are in-furrow soil applications in water only. We have not seen an iron response in other crops. Copper responses have been seen at low frequency in low organic matter sandy soil with spring wheat and durum. Canadian research also indicates that barley is responsive on these types of soils, but we have not researched it in North Dakota recently. Copper responses would not be expected in other crops. Micronutrient mixes contain not only a nutrient a crop might need, but nutrients it does not. The number of micronutrients actually beneficial and the crops they benefit are very small. A specific micronutrient application would be much more cost-effective than a blanket application over crops with little potential for benefit.

Nutrisphere™:   This product advertises its benefits as a nitrification inhibitor and a urease inhibitor. Careful laboratory experiments at NDSU by Dr. Goos and at University of Arkansas-Fayetteville by Dr. Norman have shown it does neither. Not that it only does a little, but it really has no effect at all. I think that is all I need to write. I would not recommend this product, buy this product, stock this product or sell this product. We also alerted the supplier three years ago that the product did not perform as advertised, but they too chose to ignore us.

Low-rate slow release N products:  Although low-rate slow-release N products have been successful in golf courses, their use in commercial farming is not recommended (unless you have a quarter section of daily irrigated sandy bent-grass greens). These products are no more efficient foliar-applied than UAN or other standard commercial N products. Their use in soil is limited by their high cost. A product like ESN (a polycoated urea) would be more practical due to its cost advantage over the slow-release products evaluated at NDSU during the last five years.

Humates: Humate is a warm and fuzzy word that makes one think immediately of humus, which is a desirable thing to have in soils associated with active organic matter. However, humates are made through the treatment of a high carbon material, usually a low grade coal (in our state, usually Leonardite) with strong base, and the extract is a black high organic containing, but dead material called Humic acid, or Humate. These products have been extensively tested and you can find several studies in the compendium. The only improvement in crop condition I have read about is in a very leached white sand. If there is no organic matter in soils, any organic material is good. In what I would consider a normal field soil I cannot recall a single positive yield increase from their use at recommended rates. I have conducted several studies with some of these materials and have not found a benefit.

Things that work: Urease inhibitor- Agrotain™    Nitrification inhibitor- N-Serve™ (nitrapyrin) or Instinct™ (encapsu­lated nitrapyrin), DCD if used at effective rates (Guardian™, Agrotain Plus™ or Super U™)

Summary: Be very careful when buying a new product that seems like it would perform miraculous deeds. Chances are that it does not. If you do try a product, do not just split a field or try it on one field. Enough natural variation is present in soils that it will over-shadow any true effects or non-effects. Multiple check strips evaluated with a yield monitor at harvest is a much better method of conducting farm trials. One of the red-flags from compa­nies to look out for is a statement such as ‘the University really is behind the times and doesn’t understand the product’. Unfortu­nately for the marketers of these products, we really do understand them.

Note: The mention of trademarked products is not necessarily an endorsement of the products and their use is not endorsed by me or NDSU.

Dave Franzen Extension Soil Specialist david.franzen@ndsu.edu