White Clover (Trifolium repens) Establishment within Dormant Bermudagrass Turf: Cultural Considerations, Establishment Timing, Seeding Rate, and Cool-season Companion Grass Species

Abstract

<jats:p>White clover (<jats:italic>Trifolium repens</jats:italic> L.) inclusion is a proposed means of increasing the sustainability of certain low-maintenance turfgrass scenarios through increased pollinator habitat and as a result of the legume’s ability to biologically fix atmospheric nitrogen (N). Proper white clover establishment is key to maximizing stand uniformity and N contribution to associated grasses. However, there are few guidelines for white clover establishment within warm-season turfgrasses. Four studies were conducted to evaluate seeded white clover establishment within a dormant hybrid bermudagrass [<jats:italic>Cynodon transvaalensis</jats:italic> Burtt-Davy × <jats:italic>C. dactylon</jats:italic> (L.) Pers.] lawn as affected by 1) pre-seeding mechanical surface disruption; 2) establishment timing; 3) seeding rate; and 4) companion grass species. White clover establishment was improved by scalping before October seeding, but these effects were not further enhanced by the addition of verticutting or hollow tine aerification. Unscalped turfgrass yielded nearly 50% lower white clover densities than those scalped before seeding, possibly as a result of decreased seed-to-soil contact and increased bermudagrass competition. January and February establishment dates generally yielded the lowest spring clover densities, whereas October timing yielded superior establishment. Clover densities resulting from six seeding rates (0, 0.4, 0.8, 1.5, 3.0, and 6.0 g live seed/m<jats:sup>2</jats:sup>) were fit to the linear model (<jats:italic>y = y</jats:italic><jats:sub><jats:italic>0</jats:italic></jats:sub> + <jats:italic>ax</jats:italic><jats:sup><jats:italic>b</jats:italic></jats:sup>, where <jats:italic>y</jats:italic> equals trifoliate leaves/m<jats:sup>2</jats:sup> and <jats:italic>x</jats:italic> is equal to initial seeding rate). An important feature of this model was that it accurately represented the diminishing response of increasing seeding rate. Clover establishment was negatively correlated with companion grass densities with the largest densities occurring when planted with tall fescue and the smallest when planted with annual ryegrass. Ultimately, scalping alone or in combination with other mechanical surface disruption should be paired with a clover variety acceptable to the height of cut and the environmental conditions of individual scenarios. Likewise, seeding rates and the decision to include a cool-season companion grass species will be dependent on the use of a turf and the desired green cover.</jats:p>

Preplant Cultivation Techniques and Planting Date Effects on White Clover Establishment into an Existing Cool-season Turfgrass Sward

“…Additionally, reduced turfgrass canopy can also increase production of legume stolons (Ballar e et al, 1995). McCurdy et al (2013) reported similar results in bermudagrass, where SC produced much higher WC germination than nonscalping treatments. While CA, on average, did not lower turf quality below an acceptable level, it also did not provide as favorable of an environment for WC germination and establishment as SC and VM.…”

Testing the Establishment of Eight Forbs in Mowed Lawns of Hard Fescue (Festuca brevipila) for Use in Pollinator Conservation

“…The number of plants establishing in plots can be difficult to determine for species with spreading vegetation, so aboveground vegetative units appropriate for the species were quantified on the premise it would correlate to the number of individuals establishing in a plot. This method has been most commonly applied for T. repens in the form of trifoliate leaves (McCurdy et al, 2013;Sparks et al, 2015), and was adopted here for additional species. Vegetative units were considered any structure that arose from the ground and could be reasonably counted over the entire plot.…”

Turfgrass Species Affect the Establishment and Bloom of Kura Clover (Trifolium ambiguum) in Lawns

“…Other studies have found effects of turfgrass species on forb establishment. A recent study involving white clover co-seeded with companion grasses into dormant bermudagrass found clover produced more trifoliate leaves in tall fescue compared with the faster growing varieties such as annual ryegrass (McCurdy et al, 2013). A similar study used three species of turfgrass co-seeded with birdsfoot trefoil (Lotus corniculatus L.), and found that kentucky bluegrass and red fescue typically had greater yields of birdsfoot trefoil than perennial ryegrass (Laskey and Wakefield, 1978).…”

“…An ideal turfgrass species would maintain groundcover, but also allow for establishment and bloom of its forb companions. Some effort has been made into developing seeding strategies for white clover into established lawns to benefit pollinators and soil nitrogen (McCurdy et al, 2013;Sparks et al, 2015). White clover is an established agronomic crop that is widely associated with pasture agriculture, and is well adapted to the grazing systems under which it evolved (Leffel and Gibson, 1973).…”