John and Rosie Wurpts, Ogden, are PFI members who have used Sustainable Project out a long term comparison of fertility management systems. Biological amendments ma Agrienergy, Inc. and recommended by a consultant have been compared to fertilization p on soil tests and ISU Extension recommendations. Input costs have been lower in the IS because, based on soil testing, usually only nitrogen has been recommended. Based on costs, the ISU recommendations were favored by $8.15 in soybeans and $22.85 in corn years that these replicated trials have been continued, the only significant yield differenc 1991 weed problem in corn in the biological system. The average economic benefit of th recommendations compared to the biological ones has been $26.63 in corn and $20.69
The Neely-Kinyon Farm, in Greenfield, evaluated ACA, a zinc ammonium acetate additive that in very small amounts has sometimes increased corn N uptake (Table 2). The three treatments were: starter fertilizer, starter-plus-ACA, and a check treatment with neither ACA nor starter. Mid-season leaf tissue samples showed no difference among the three practices in nitrogen, phosphorus or potassium, although leaves in the ACA treatment were lower in sulfur. The three yields were not significantly different, so the economic advantage went to the no-fertilizer control treatment.