Turfgrass species and sward age influence soil carbon pools near the soil surface

Abstract Enhancing soil carbon (C) sequestration helps reduce atmospheric carbon dioxide concentrations. Turfgrasses are important crops in the urban environment and have shown potential for C sequestration. However, little is known about how turfgrass species selection affects soil C concentration or how this varies over time. The objectives of this research were to evaluate the effect of three turfgrass species, sward age, and soil sampling depth on total soil C and N, soil organic matter (SOM), and labile soil C. A total of 25 locations throughout Indiana were sampled from established swards of Kentucky bluegrass ( Poa pratensis L.), tall fescue [ Festuca arundinacea Schreb.; syn. Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.], and zoysiagrass ( Zoysia japonica Steud.) with varying sward age. Turfgrass species affected soil total C and labile C concentrations but had no effect on soil total nitrogen (N) or SOM. Differences between the C pools of soils under turf 0–10 years in age compared to those 11–25 years in age only occurred near the soil surface. As turf swards age, total soil C, total soil N, and SOM increased near the soil surface (0‐ to 7.5‐cm depth) and little beyond the 7.5 cm in depth. The strong relationship ( p ≤ 0.0001, R 2 > 0.57) between total N, SOM, and labile C highlighted their interplay in the mineralization of N from SOM and changes in the short‐term C pool of a turfgrass system.