Short-term soil carbon mineralization on golf course sand-based putting green and its effect on creeping bentgrass nitrogen uptake

A rapid soil test for accurately estimating nitrogen (N) supply from soil organic matter would help turfgrass managers develop N fertilization programs. In this study, we tested the feasibility of using a quick test, mineralizable carbon (min-C), to predict turfgrass growth and N uptake from sand-based putting green soils. A 2-year field experiment was conducted in Verona, WI, on four sand-based research golf greens planted with creeping bentgrass. Nitrogen fertilizer was applied at 0, 10, and 20 kg ha-1 every 2 weeks as liquid urea during the growing seasons. Soil samples were collected at 0-5 cm and 5-10 cm and tested for min-C by measuring the flush of CO2 following the rewetting dried soil, where the soil was rewetted at 50% water-filled pore space and incubated at 25 degrees C for 24 h. Min-C was greater at the shallower soil depth, and unaffected by N rates that were applied. On-site air temperature, soil moisture content, and estimated soil temperature were negatively related with min-C, where r2 = 0.26-0.60 for air temperature, r2 = 0.32-0.71 for soil moisture content, and r2 = 0.16-0.53 for estimated soil temperature, indicating the test is quite sensitive to environmental conditions at the time of sampling. Furthermore, min-C had weak positive to no relationship with creeping bentgrass growth rate (r2 = 0-0.17) and N uptake (r2 = 0-0.23) on sand-based putting green, suggesting the test does not hold promise as a method for improving fertilizer decisions to these systems. Soil mineralizable C was not predictive of creeping bentgrass growth or N uptake on sand-based putting greens.Soil mineralizable C was substantially influenced by sampling depths on sand-based putting green.Environmental variables including air temperature, soil temperature, and soil moisture affected soil mineralizable C of sand-based putting greens.