Organic matter and nutrient content within putting green root zones in Tennessee

Organic matter and soil nutrient accumulation within putting green root zones affects surface quality and performance. Research was conducted to explore differences in organic matter and nutrient content within creeping bentgrass (CBG; Agrostis stolonifera L.) and ultradwarf bermudagrass [UDBG; C. dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] putting greens. Sampling was conducted from January 30 to February 23, 2023, on 22 putting greens (11 CBG and 11 UDBG) in Tennessee. Forty cores (1.91-cm diameter by 10-cm depth) were randomly collected from each putting green and analyzed for total organic material (TOM; undisturbed cores) by profile depth (0–2 cm, 2–4 cm, and 4–6 cm), TOM throughout a 10-cm core, soil organic matter (SOM; passed through sieve with 2 mm openings) throughout a 10-cm core, and nutrient content. All organic matter measurements were determined via loss-on-ignition (LOI) testing, whereas nutrient content was determined by Mehlich-3 extraction. LOI testing at 440°C resulted in greater TOM values than 360°C; however, values from both temperatures were closely related (R² = 0.99). TOM values from UDBG greens were greater than those recorded on CBG at all profile depths. Greens established via no-till conversion contained more TOM than those planted in a constructed sand-matrix root zone. While TOM and SOM were associated (R² = 0.62), removing verdure for SOM assessments reduced the amount of organic material in each sample by 38% and increased variability. Nutrient contents were lower than sufficiency level of available nutrients benchmarks but exceeded minimum levels for sustainable nutrition.