Evaluating Soil Carbon Sequestration Potential for Turfgrass Species Grown in the Transition Zone
Recent efforts have attempted to quantify management practices that enhance soil carbon (C) sequestration in turfgrass systems. However, the effect of turfgrass species has remained mostly unstudied, despite turfgrass species differing in their photosynthetic pathway and adaptability. Therefore, the objectives of this research were to: 1) quantify carbon dioxide (CO2 ), and nitrous oxide (N2O) emissions for Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), tall fescue [Lolium arundinaceum (Schreb.) Darbysh], bermudagrass [Cynodon dactylon (L.) Pers.] and zoysiagrass (Zoysia japonica Steud.) across growing seasons; 2) evaluate the effect of three turfgrass species (Kentucky bluegrass, tall fescue, and zoysiagrass), sward age, and soil sampling depth on soil C, N, soil organic matter (SOM) and permanganate oxidizable carbon (POXC) concentrations from swards of varying age located throughout Indiana; and 3) quantify the effect of bermudagrass, creeping bentgrass (Agrostis stolonifera L.), Kentucky bluegrass, tall fescue, and zoysiagrass residue additions on microbial activity and soil aggregate stability in a microcosm study. Greenhouse gas emissions were strongly influenced by photosynthetic pathway, with the cool-season (C3) species of Kentucky bluegrass, perennial ryegrass, and tall fescue among the species with the highest CO2 and N 2O fluxes, while the warm-season (C4) species of bermudagrass and zoysiagrass were among the species with the lowest CO2 and N2O fluxes across the 14 sampling dates. Turfgrass species significantly affected soil total C and POXC concentrations, but had no effect on soil total N or SOM. The species with the highest total soil C was Kentucky bluegrass, followed by zoysiagrass and tall fescue. Conversely, POXC concentration was lower for Kentucky bluegrass than zoysiagrass. Surprisingly, we saw few differences between the C pools of soils under younger turf swards (0-10 years in age) compared to older swards (11-25 years in age). It was evident that as turf swards age, total soil C, total soil N, and SOM increase most near the soil surface (0 to 7.5 cm depth) and little beyond 7.5 cm in depth. Residues from different species affected soil microbial activity, soil aggregate mean weight diameter (MWD), total soil C and N, soil C:N ratio, and total phenolic acid content in the microcosm experiments. Although turfgrass species residue treatments initially (>14 d after initiation) differed in their effect on soil microbial activity, these differences were negligible after 80 d. Despite all turfgrass residues resulting in higher MWD than the non-treated control, MWD never differed among turfgrass species throughout the duration of the microcosm experiment. This research demonstrated that turfgrass species vary in their influence on soil C and N cycling. Species exerted a strong influence on GHG emissions and soil C dynamics, but residue quality analysis indicated small differences between species and few effects on soil microbial activity and soil aggregation. Therefore other factors not examined in this research such as residue biomass, labile residue quality, or microbial community dynamics may be contributing to the differences in GHG emissions and soil C between turfgrass species measured in this research.
Patton, Purdue University.
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