THE INFLUENCE OF LIQUID SEAWEED PRODUCTS ON TURF GRASS GROWTH AND DEVELOPMENT

Today, many factors including regular close grass mowing, increasing all year round use, compaction and an inert sand based rootzone combine to stress turfgrass plants. This stress is exacerbated through limited leaf photosynthesis and hence verdure growth. Environmental awareness, escalating costs of synthetic fertilisers and high transport costs is making renewable nutrient resources such as seaweed extracts worthy of consideration as alternative turfgrass growth stimulants.
Perennial ryegrass (Lolium preene L. ‘Barcredo’ seed was sown and germinated in sand filled 100 mm pots during October 1998 in a heated glasshouse under natural light conditions. Liquid seaweed extracts (Kelpak and Marigrow) were applied as a drench to the rootzone at either 0.1% or 0.2% separately or in combination with inorganic nutrients at weekly intervals. Leaf colour was ranked by visual appearance on a scale of one to five. Growth was measured weekly just prior to treatment application. Potassium and phosphorus tissue and rootzone levels together with rootzone organic matter were also measured. While both seaweed extracts alone were capable of sustaining grass growth, Marigrow in combination with normal nutrient levels induced the best grass colour. Organic matter levels in the rootzone were enhanced where seaweed concentrate was applied without inorganic nutrients. Kelpac and Marigrow contained insufficient levels of potassium (K) and phosphorus (P) to satisfy rootzone potassium and phosphorus sufficiency levels. Both products satisfied tissue potassium and phosphorus sufficiency levels. The work demonstrated that selected seaweed extracts may have application in managing sportsturf.