Clover (Trifolium spp.) Inclusion in Kentucky Bluegrass (Poa pratensis) Lawns

Abstract

Historically, white clover (Trifolium repens) seed was included in turfgrass seed mixtures to provide biodiversity and nitrogen (N) to lawns. White clover dicultures have been studied recently for inclusion in both warm- and cool-season turfgrasses, with the goals of reducing fertilizer applications and providing pollinator forage in lawns; however, other clovers have not been as widely researched in turfgrass. The objectives of this study were to evaluate 1) if white, strawberry (T. fragiferum), crimson (T. incarnatum), and rose (T. hirtum) clovers can persist in dicultures with Kentucky bluegrass (Poa pratensis); 2) if clover inclusion in dicultures impacts broadleaf weed cover; and 3) if low levels of N fertilization impact clover persistence or quality of clover–bluegrass dicultures. Kentucky bluegrass was grown as a monoculture or as a diculture with each of the four clover species. Each mono- or diculture was then treated with a low rate of N fertilizer (48.8 kg⋅ha–1 N) or no N fertilizer to determine quality and percentage of grass, clover, or weed and bare-soil cover. Dicultures contained similar or less weed and bare-soil cover, and maintained similar or greater quality compared with bluegrass monocultures, indicating clover and Kentucky bluegrass dicultures are suitable alternatives to Kentucky bluegrass monoculture lawns, and can potentially lead to reduced fertilizer and pesticide requirements. Fertilizer generally had no effect on cover, likely because of the low rates of N applied.