Seedling Performance Associated with Live or Herbicide Treated Tall Fescue

Abstract

Tall fescue is an important forage grass which can host systemic fungal endophytes. The association of host grass and endophyte is known to influence herbivore behavior and host plant competition for resources. Establishing legumes into existing tall fescue sods is a desirable means to acquire nitrogen and enhance the nutritive value of forage for livestock production. Competition from existing tall fescue typically must be controlled to ensure interseeding success. We used a soil-on-agar method to determine if soil from intact, living (L), or an herbicide killed (K) tall fescue sward influenced germination and seedling growth of three cultivars of tall fescue (E+, MaxQ, and E−) or legumes (alfalfa, red clover, and white clover). After 30 days, seedlings were larger and present in greater numbers when grown in L soil rather than K soil. Root growth of legumes (especially white clover) and tall fescue (especially MaxQ) were not as vigorous in K soil as L soil. While shoot biomass was similar for all cultivars of tall fescue in L soil, MaxQ produced less herbage when grown in K soil. Our data suggest establishing legumes or fescue cultivars may not be improved by first killing the existing fescue sod and seedling performance can exhibit significant interseasonal variation, related only to soil conditions.

Determining Thresholds for Grassland Renovation by Sod-Seeding

“…Sod-seeding in ryegrass at an initial sward coverage above 10% did not allow a successful red clover seedling establishment in our study, neither in late summer, nor in early spring. Previous trials (9) in the same region showed that ryegrass sward renovation by sod-seeding or wet-seeding was successful only in fields with >50% bare soil, and although new ryegrass plants established, no improvements were measurable in total forage yield [28]. The authors concluded that sward renovation might only be profitable when forage yield and quality are improved, with the least costs for labor and seeds.…”

“…The most commonly used legume species in Northern Europe and Northern America are red clover (Trifolium pratense L.), white clover (Trifolium repens L.), and alfalfa (Medicago sativa L.), which mainly contribute with potential nitrogen fixation, stabilization of forage dry matter and increasing forage protein content [3,4,7]. However, introducing legumes can be very challenging, particularly in well-established stands where competition is strong [8,9]. Such stands may have a good sward coverage (e.g., >75%) across the field, and some phytotoxins may be released through the living grass roots to prevent germination and root growth of legume seedlings [10] or through the decomposition of grass killed by ice-encasement [8].…”

“…Sod-seeding has been subject of research for many decades, to determine effectiveness of the seed drill [13]; identify optimal seed mixtures and seeding rates [1]; determine functions in ecosystems of grass mixtures [14]; establishment success in relation to sowing methods, depth and width of cultivation and sowing date [3,6,8]; effects of suppression treatments prior reseeding to reduce competition with existing sward [5,9]; identification of factors determining establishment success of newly sown forage legumes [4]; and effects of application of slurry together with sod-seeding in one operation [15]. This research has led to the development of many general guidelines concerning how to ensure establishment success, often involving measures to improve the contact between seeds and soil by tillage and management operations to reduce competition from the existing sward, such as defoliation or herbicide application.…”