So, what is an ideal sand depth to strive for during aeration? Well, it depends on the specific rootzone characteristics. New putting greens that were built with a sand-based rootzone in accordance with USGA construction recommendations will generally only benefit from adding sand in the upper few inches of the soil where organic matter has started to accumulate. Adding sand past that depth, into the original sand mix that was installed during construction, is a waste of time and resources that will not make the putting greens perform any better.
Conversely, an older putting green that has accumulated more organic matter could likely benefit from deeper cultivation techniques. Using deep-tine aeration, drill-and-fill, or DryJect® Maximus to push sand to depths of 8 to 10 inches could prove useful. These more-aggressive aeration techniques have also been used with success on pushup greens to improve drainage and increase soil porosity.
Regardless of the specific aeration equipment you have at your disposal, make sure that your target aeration depth matches with the organic matter depth. The goal during aeration should be to punch through any distinct soil layers that could hinder root development and to add sand where organic matter is becoming too concentrated. Regular soil testing can be used to track levels of organic matter, but a lot can be gleaned from observations in the field. Such sampling is a major component during USGA Course Consulting Service visits and a great way to evaluate your cultural management program. I suggest examining several soil profile samples from your putting greens and adjusting your aeration depth accordingly.
Central Region Agronomists:
John Daniels, agronomist – email@example.com
Zach Nicoludis, agronomist – firstname.lastname@example.org