Golfdom, January 2013

Super Science Continued from page 55 to the pea gravel layer removed the oxidized iron layer with a shovel and replaced the root zone with fresh sand In the short term we were successful in improving water infltration in these low areas However our fx was only temporary the factors that caused the layer to form in the frst place were still active and the layer will likely form in these areas again over time One day we were sampling and thinking about how the layer might be forming We had many questions Where is this iron coming from What factors are causing the iron to oxidize and precipitate at the sand gravel interface How do we remove this layer once it has already formed How can we prevent it from forming in the future Finally the superintendent suggested Go to graduate school study this for your masters degree Tat is exactly what I did University research A few years later I started graduate school at UW Madison Te superintendent from Hawaii sent me some samples of this layer and I confirmed that it was oxidized iron through physical and chemical analyses I thought it was a rare unique problem when I frst witnessed it in Hawaii But now that Ive studied it more and more I have seen this iron layer in Texas Missouri Virginia Pennsylvania West Virginia California North Carolina and even Vietnam Te layer seems to occur all over the United States and doesnt seem to be restricted to any specifc climate zones For my masters research I am trying to fnd out exactly what causes this layer to form how to prevent it and what to do if you already have it Te iron could be coming from fertilizer high rates of iron fertilizer have become popular for Poa annua management programs and many superintendents FiGUre 3 When we take soil samples we usually pull several plugs from the top 3 6 inches of the profile From this we get a wealth of information apply iron to improve turfgrass color Te iron could also be coming from irrigation water many golf courses use groundwater that contains dissolved iron and the amount of iron added through typical irrigation operations is comparable to typical iron fertility rates Finally iron could be coming from the dissolution of minerals in the sand used for root zone construction Most likely all of these sources FiGUre 2 Iron layer at sand gravel interface 12 inch depth of Hawaii putting green The layer reduced water infiltration resulting in anaerobic soil conditions and thin turf density at the surface Iron layer in a Wisconsin putting green The oxygenated pea gravel layer causes reduced iron in the root zone to oxidize at the textural interface The darker black color is older strongly oxidized iron the light orange color is recent weakly oxidized iron 56 Golfdom January 2013 Golfdom com