Iron Impregnated Elemental Sulfur Application to Kentucky Bluegrass Turf: Rates and Application Method.

Problems occur when landscape managers apply excess nitrogen (N) to maintain an aesthetically pleasing turf. Shallow roots (resulting in unsafe athletic fields), excess shoot growth, and ground water contamination are problems associated with over applying N. Applying iron (Fe) in addition to N has proven to reduce N application and correct chlorosis. However, current Fe treatments are ineffective or labor/cost intensive. A new Fe fertilizer, elemental sulfur impregnated with Fe (ES-Fe), was evaluated when applied to Kentucky bluegrass (Poa pratensis L.) at three rates (49, 196, and 784 kg Fe ha^-1) applied either to the surface or mixed into either an alkaline sand or a calcareous loam and compared to an untreated check. All treatments received a balanced rate of S. The turfgrass was grown in a glasshouse over 18 weeks. Clippings were harvested every 3-4 days and cumulative yields were measured periodically. Analysis of Fe and S was performed on the clippings by ICP. Chlorophyll content was estimated using SPAD meter. The concentration of both Fe and S was significantly increased by 12 and 45%, respectively, over the untreated check for all Fe treatments, with a significant impact for rate, but not for soil or application method. Clipping yield and visual and SPAD readings were unaffected by treatment. Iron chlorosis was not observed in any treated turfgrass, probably due to conditions related to growth in a glasshouse. Despite the lack of chlorosis, these results suggest that the new ES fertilizer is effective in supplying Fe and S to turfgrass.