Iron Layer Development in Sand-Based Greens

110113 Research Update


Photo Caption: USGA-sponsored field research at the University of Wisconsin-Madison has revealed that iron (red) and manganese (black) can accumulate in a USGA putting green rootzone at the interface between the sand and gravel. The layers are most likely to occur at low areas on the putting green where water tends to accumulate before draining from the green.

Have you ever you sampled the full profile of your sand-based putting greens? Very rarely, if ever, are the sand rootzones of putting greens sampled all the way down to the pea gravel layer. However, USGA-funded research from the University of Wisconsin-Madison suggests we might be missing the full picture when we fail to sample to the depth of the pea gravel. Iron-oxide layering has been observed at the sand-gravel interface of putting greens for some golf courses across the United States. This layer, which may form in greens just above the pea gravel layer, decreases water infiltration that leads to anaerobic soil conditions and poor turfgrass quality.

Soil scientists are trying to find out exactly what causes this layer to form and how to prevent it. The iron could be coming from applications to improve turfgrass color. The iron also could be in irrigation water. Many golf courses use groundwater that contains dissolved iron, and the amount of iron added through irrigation could be the problem. Finally, iron could be coming from the breakdown of minerals in the sand used for root zone construction. Most likely, all of these sources could contribute to the formation of the iron layer to some degree.

Six golf courses that had putting green problems were identified by USGA Green Section agronomists or golf course superintendents. The putting greens, built using the USGA Method of Putting Green Construction, were chosen from distinct climates in the United States and ranged in age from nine to 35 years. The iron layer, as well as a manganese layer, was more severe in samples taken from poorly-drained areas of putting greens. Scientists suggest that iron applications and irrigation water be carefully monitored to prevent the risk of the iron layer formation. Future studies will investigate the contribution of iron sources to determine effective methods that prevent iron layers from forming.

Additional Information:

Iron layering in two-tiered putting greens




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