Turfgrass Selection and Grass Clippings Management Influence Soil Carbon and Nitrogen Dynamics

Core Ideas Less than 3 yr post‐establishment, tall fescue accumulated more soil C (i.e., labile soil C, total soil C, and soil organic matter) than Kentucky bluegrass. Returning grass clippings for 2 yr increased both soil C (i.e., labile soil C and total soil C) and N (i.e., total soil N) compared to collecting clippings over the same period. Labile soil C increased linearly over the 5 yr of the experiment. Little information is available about how grass species and management practices, such as grass clippings management, influence soil C and N accumulation, especially labile soil C. Thus, the objective of this field experiment was to determine the labile soil C, total soil C, soil organic matter (SOM), and total soil N accumulation of Kentucky bluegrass ( Poa pratensis L.) and tall fescue [ Schedonorus arundinaceus (Schreb.) Dumort. syn. Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh.] cultivars with differing growth rates under different grass clippings management practices. Differences in labile and total soil C occurred between turfgrass species after less than 3 yr of growth post planting: labile soil C was 9.9% higher (851 vs. 774 mg C kg −1 soil), total soil C was 4.2% higher (24.8 vs. 23.8 g C kg −1 soil), and SOM was 8.0% higher (41.7 vs. 38.6 g SOM kg −1 soil) for tall fescue than Kentucky bluegrass. After 2 yr of clippings management treatments, plots where grass clippings were returned had 3.3% more labile soil C (826 vs. 800 mg C kg −1 soil), 3.3% more total soil C (24.7 vs. 23.9 g C kg −1 soil), and 4.6% more total soil N (2.28 vs. 2.18 g N kg −1 soil) than those where clippings were collected. However, grass clippings management did not affect SOM. The results of this study highlight the importance of turfgrass selection and grass clippings management on soil C and N accumulation.