Avail® is promoted as a starter fertilizer additive, with claims that it prevents or reduces the conversion of soluble phosphorus (P) fertilizer to less soluble forms in the soil, keeping it in plant available form for longer.
It is available for use with either liquid or granular phosphate fertilizers. In dry form, it is designed to be coated on the granular fertilizers to provide a water-soluble shield that expands and blocks elements that are attracted to phosphorus in the soil.
A search of the scientific literature and grey literature (conference proceedings etc.) was conducted to locate data on crop yield responses for AVAIL®.
In the available studies, Avail® produced an average wheat yield gain of nearly 8%, and an average corn grain yield increase of almost 6%. These yield benefits may be associated with increased efficiency in terms of various inputs, but overall environmental impacts are uncertain. None of the available studies on this product reported any measurement of nutrient losses.
Caution is warranted in extending these results to other soil and climatic conditions, at least until additional data are available to support such conclusions. Only one source of data in the reviewed literature was in a peer-reviewed scientific journal, and most observations were not accompanied by details about field management, soil conditions, and other key information.
Given the possible low quality of these data, there may be a greater likelihood of missing (unreported) experiments for which results were inconclusive or negative (i.e., publication bias). Well-documented, repeatable experiments are needed in order to establish confidence in the mechanisms and overall responses of both yield and nutrient losses. Furthermore, since the measured response to Avail® is highly variable from year to year (and between locations), further experiments should be conducted to determine the specific conditions for which the product provides a yield benefit.