Iron Impregnated Elemental Sulfur Aplication to Kentucky Bluegrass Turf: Comparison with Standard Fertilization Methods.

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 compared to elemental sulfur alone (ES) and three predominate Fe fertilization techniques, including: broadcast ferrous sulfate (FS), broadcast chelated Fe applied to soil (CS), and foliar applied chelated Fe (CF). The treatments were applied to two Kentucky bluegrass (Poa pratensis L.) varieties with differing susceptibility to iron chlorosis grown in calcareous soil. The ES-Fe and FS treatments received an equivalent of 49 kg Fe ha^-1 applied pre-plant and worked into the top cm of soil. Both chelated Fe treatments received 0.9 kg Fe ha^-1 applied every 14 days for a total of 49 kg Fe ha^-1. 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 9 and 41%, respectively, over the untreated check for all Fe treatments, but 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.