Evaluation of MicroEssentials Sulfur Fertilizer Products for Corn Production, 2009

The main objective of this study was to evaluate the 12-40-0-10S product (MicroEssentials MES10^®), comprised of monoammonium phosphate (MAP) plus ammonium sulfate (AMS) and elemental S in equal proportions, as a S and P fertilizer source for corn production. A second objective was to provide additional data on the potential for corn response to S fertilization in Iowa. In addition, a second MicroEssentials product (MESZ^® 12-40-0-10S-1Zn) was evaluated as a Zn fertilizer source. Sites were chosen in Mason City and Madrid, Iowa, based on their potential for soil S deficiency.

Results indicate a similar plant S uptake response to all S fertilizer products, but no yield response to S application at either site in 2009. A plant P uptake response was observed with all P fertilizer products, and a yield increase to applied P was found at the Madrid site and when analyzed across sites. A yield increase from P application was present for each product. However, for an unknown reason, the yield with the MES^® product when applied at the 30 lb S/A rate resulted in no yield response at both sites compared to the control. This also occurred for the MAP product at the Madrid site. The products were surface-applied at both sites, with one difference being the Madrid site was tilled and the Mason City site was under no-tillage. However, other P and S applications (either as different products or at a lower rate of MES^®) did not generate such low yields as all of these combinations produced a yield increase from P application.

Based on the results in 2009, no real difference was noted between the S or P fertilizer products. There was no yield increase with application of Zn as MESZ^®. The MESZ^® product also appeared to supply equivalent S and P compared to the AMS and MES^® products. The MESZ^® product did not have the yield issue noted with the high rate of MES^®. This lends further evidence that the lower yield with the MES-30^® and MAP-30 treatments was due to something besides product application, although that is unconfirmed. IA-19F

Annual Reports