the inner wall of the shell is maintained at approximately 140 u00b0 150 u00b0 f no heat is applied to the last half of the dryer and the product is allowed to cool as it travels the length of the dryer solidifying and exiting as a granular or semi granular product at about 90 u00b0 f to assist in directing the flow of vapors and fertilizers in the dryer as well as enhance heat transfer a small amount of sweep gas e g nitrogen may be introduced to the dryer the fertilizer produced by this process is comprised of a seed material coated with nutrients and micronutrients and optionally one or more biologically active agents exemplary seed materials include potassium nitrate ammonium nitrate urea calcium nitrate sodium nitrate potassium sulfate and ammonium sulfate generally in the form of prills the seed material should be selected so as to meet the desired size restrictions i e granular or semi granular the seed material is coated with a coating containing nutrients and secondary micronutrients as exemplary nutrients one or more of phorphous potassium and urea may be included in the mixture it is important to note that in contrast to prior art systems urea need not be present for the formation of a coating about the prill and is included optionally only as a nutrient if urea is either not desired or is supplied by an alternative source the fertilizer may omit urea the fertilizer may also include a buffer which.