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2006 Annual Report: Avail® Fertilizer Additive


Avail is a water soluble additive for granular or liquid phosphorus fertilizer and acts to keep the phosphorus available upon reaching the soil. This product is marketed by United Suppliers. Research by Universities is limited; however, research by the University of Idaho with phosphorus fertilizers applied to potatoes on calcareous soils has shown a yield response.

We were approached by a local dealer to examine if this product had any value in protecting urea from volatilization. Again, this is not what the product is designed for.

Our objective was to determine if the use of Avail would increase the efficiency of urea fertilizer despite its recommended use to increase phosphate availability.

Methods and Materials

Planting Date: April 18, 2006
Herbicides: Pre: Glyphosate + Dual + Atrazine + Callisto Post: Accent + Clarity
Hybrid: Pioneer 34B24
Insecticides: Lorsban Banded 8oz/1000ft
Population: 32,400 seeds/acre
Row Width: 30-inch
Supplemental nitrogen applications of: Urea, Urea +Avail, Urea + Agrotain

Two treatments of pre-plant ammonium nitrate and urea were applied at a rate of 120 pounds per acre. An additional 40 pounds of nitrogen were applied top-dressed over corn on May 4 with the different urea treatments.


There were no significant differences between the ammonium nitrate and urea preplant treatments. Also, there were not any significant differences between the 40 pound supplemental nitrogen treatments of urea, urea plus Agrotain and urea plus Avail.