Lately, I have been receiving many inquiries regarding my (or Purdue) recommendations on the use of Amisorb. At the risk of irritating some and confusing others, I feel compelled to put down a few thoughts on the product.
What is it? It is a polyaspartic acid, a relative of Nutrasweet, that has seen a number of industrial uses from adhesives to shampoo. It is non-toxic, biodegradable, and, as a crop production system additive, non-absorbable. It does not end up in grain or other plant tissue. It is currently being marketed as a root growth stimulator that enhances root branching and root hair development, and improves nutrient uptake that can result in increased yields and yield quality. It is not being sold as a replacement for fertilizer!
Does it improve plant nutrient level? There have been quite a few controlled environment studies and a limited number of field studies that have looked at plant nutrient levels. Some of the earliest investigations were done in Illinois with hydroponically-grown (a soilless rooting environment) wheat. Shoot levels of N, K, Ca, Mg, Mn, and Zn increased when Amisorb was included in the rooting media. However, studies at Texas A&M on coastal bermuda grass did not find a similar response. For corn tissue concentrations, a Princeton Kentucky study found Amisorb increased ear-leaf N concentrations, but only when the supply of N to the root was low. In this study, Amisorb did not affect ear-leaf concentrations of P, K, Ca, Mg, S, Zn, B, Cu, Mn, or Fe.
But, does it improve yields? Of course, the question that interests everyone is whether use of the product translates into increased yields in the field. To put it bluntly, results from field trails have been mixed. Last summer, Dr. Keith Kelling, an extension specialist at University of Wisconsin, Madison, reviewed all the studies that had been completed in the north central region and summarized them in a table (Table 1). He noted that some substantial responses to the product have been observed. For corn, a trial at Urbana, IL showed a 16 bu/acre yield response when Amisorb was incorporated in a band between rows, and a Scandia, KS study showed a 13 bu/acre yield response to Amisorb placed with starter (2 qt/acre rate). But results were far from consistent with only five out of nineteen studies on corn showing a significant positive response to Amisorb. Over all the studies on corn, the average yield change from the product was a scant 2 bu/acre increase. Similar, less-than-conclusive results were seen in the seven experiments on soybean and the eighteen experiments on wheat.
Dr. Kelling observed that the results from corn appear the most consistent, but he also noted that there did not seem to be a set of identifiable environmental conditions under which a field response to Amisorb is more (or less) likely. For example, since Amisorb is a "root growth enhancer" you might expect that greatest responses to the product would occur in soils testing low for P and K but that does not necessarily appear to be so. The Urbana corn response happened on soils with P test levels of 20 ppm and K test levels of 130 ppm. Dr. Kelling did note, however, that there does seem to be some indication that placement of the product near the plant versus broadcasting is a good idea.
|Table 1. Summary of yield responses to Amisorb in experiments conducted in the north central region.|
|Number of experiments||19||7||18||5|
|Number with significant response||5||1||4||0|
|Average yield change, bu/acre||+1.9||+0.7||+1.3||-0.5|
|As summarized by Dr. K. Kelling, University of Wisconsin, Madison|
What about product testing in Indiana? Dr. Dave Mengel (formerly in this department, now Head of the Agronomy Department at Kansas State "Stop and say hi if youre passing through on I-70") ran a set of field trails last year in Columbia City and West Lafayette, Indiana. For corn, soybeans, and wheat, Dr. Mengel compared a number of application methods and rates. In Table 2, I have summarized his results, listing the yield without Amisorb, the average yield increase or decrease for all rates and methods of application of the product, and the significance of the yield change. For your information (because I know you are curious), I have also listed the highest yield observed for an Amisorb treatment and the rate and method of Amisorb application in that treatment. Please note, this is not a recommendation on how to use the product. While some applications appeared to increase average yields, the response was so variable ("unpredictable") that it cannot be considered a significant response ("reliable" or "likely to happen again") for any rate or application method on the three crops tested.
|Table 2. Corn, soybean, and wheat yield response to Amisorb in Indiana (data from D.B. Mengel, 1997 crop year only).|
|Corn (bu/a)||Soybean (bu/a)||Wheat (bu/a)|
|Average Yield Change with Amisorb (all methods of application)||+1.8||-0.2||+1.3|
|Significant response to Amisorb?||No||No||No|
|Yield from most responsive Amisorb treatment (treatment application method)||132 (1 qt w/ starter & 1 qt w/ sidedress N)||51.1 (2 qt ai @ 10% granules broadcast)||56.9 (2 qt fall applied)|
What are the commercial recommendations for product use? Typically, a one to two qu/acre application rate is being recommended for corn, soybeans, or wheat. It can be mixed with liquid fertilizer, impregnated on dry fertilizer, or soil-applied. The cost of an application ranges from $8 to $15 dollars per acre.
You now have as much information as I do on the success of the product. I hope it helps in your decision on whether to invest in the product.