Issue No. 20, Article 6/August 8, 2008
Nontraditional Fertilizer and Additive Products
Every year many products circulate the fertilizer market claiming to replace commercial fertilizers, to make nutrients in the soil more available, to cost less than traditional fertilizers, to supply micronutrients, or to be a natural product. While some of the claims may be true, more often they are not, or at best are partially true.
Generally speaking one can distinguish between soil additives and fertilizers by the fact that additives have little or no nutrient content, and there is no requirement, as with fertilizers, to have a guaranteed analysis label (e.g., 11-48-0). Those who promote the products typically use testimonials from farmers and present data from suspect sources. Commonly they tout either a substantial increase in yield or a small increase of 2 to 4 bushels an acre. When high yields are being advertised, remember: You get what you pay for. I would ask myself, If a product can produce such increases, why is it so inexpensive? On the other hand, if the yield increase is only a few bushels, it is often difficult to determine whether the increase is related to treatment because those supposed increases are within the inherent variability of most field studies.
The types of products being advertised can be broadly assigned to three categories: soil activators, wetting agents or surfactants, and soil conditioners. Some products are said to introduce beneficial organisms or to stimulate existing soil microbes. While these so-called soil activators might increase microbial activity, their effect compared to what is already present in the soil can be considered a drop in the bucket that does not translate into improved yield.
Products sold as wetting agents or surfactants are successfully used to improve the surface coverage of insecticides and herbicides by reducing water surface tension. However, there is no basis for using such products to improve water infiltration and retention in the soil or to loosen compacted soils.
Products advertised as soil conditioners are designed to improve the physical condition of the soil and thus enhance aeration, root growth, and water retention. The typical products in this category contain humates and humic acid, or some other type of organic material mixed with inorganic elements such as rock phosphate, limestone, or some other mined mineral that has been ground.
The best approach with new products is caution. If the product is being advertised to make nutrients more available in the soil, ask yourself, If the product increases the availability of a particular nutrient, how can it increase yields (as is being advertised) in a field where that nutrient is already present in ample quantities? Other points to consider are these: Do I have problems with this nutrient in my field? Have I seen micronutrient deficiencies there? More often than not you will find that you do not need the product, and if you discover that you are lacking in a particular nutrient it is better to invest in products that have been proven through time.
People promoting new products are well versed in selling techniques and can be very persuasive. If you become convinced that you really need a given product, or you are simply curious to find out how well it works, take a conservative approach. Apply it only on an experimental basis so you can be your own judge.
The extension specialists at the University of Illinois stand ready to provide guidelines on how to set up an experimental trial and to give unbiased advice when asked about purchasing new products. An additional resource that may be useful for information on new products is the Compendium of Research Reports on Use of Non-traditional Materials for Crop Production. This electronic compendium contains abstracts, data, and reports on a number of nontraditional products marketed for use in crop production in the north-central region of the U.S. that have been tested by scientists in state agricultural experiment stations. Not all products (especially those just being advertised) are included, but be aware that new products are often old ones being advertised with new names. When that is the case, there may be research already available. You can search for a specific product by name or by type (surfactant, foliar additive, seed coating, soil conditioner, inoculant, soil activator, wetting agent, microbial enhancer, etc.). The compendium is provided by the North Central Region NCR-103 committee on nontraditional soil amendments and growth stimulants; it can be accessed free at extension.agron.iastate.edu/compendium.--Fabián G. Fernández