Core Aerification Amount, Frequency and Topdressing Rate On Soil Physical Properties

Soil compaction is an issue faced by turfgrass managers in areas with heavy traffic such as golf course putting greens and sports fields.  While much research exists on the benefits of proper aerification, little exists quantifying the optimum amount of surface area removed on a yearly basis, the number of aerifications needed to reach the optimum surface area impacted, nor optimum amounts of topdressing applied post-aerification. A study was conducted at Clemson University, Clemson, SC in 2008 and 2009 on a 10-year old USGA-specified “TifEagle” bermudagrass putting green and included two percentages of surface area removed or impacted per year, 15 and 25%.  Each impacted area treatment was core aerified either once, twice, or three times yearly, with cores removed.  Following aerification, each treatment received one of two topdressing rates; the mathematical equivalent of soil removed with aerification or one-half this rate.  Parameters measured included turf quality, bulk density, surface hardness, infiltration, thatch depth and thatch weight. Topdressing did not impact any measured parameter while the untreated had highest average turf quality throughout the study.  Turf quality temporarily decreased with increasing surface area impacted and frequency of aerification. Surface hardness was greatest in non-aerified treatments as increasing aerification frequency decreased this, regardless of percent surface area impacted.  Differences were not evident in bulk density or infiltration in either study year.  Thatch weight and thatch depth were similar in year one, however in year two, the untreated had higher thatch weight compared to all other treatments while thatch depth remained similar. In conclusion, as core aerification impacted area increased, turf quality temporarily declined. However, most other soil parameters measured improved. Future research will continue to evaluate the timing of aerification and amount of surface area impacted to optimize the effectiveness of aerification practices.