Evaluation of Organic Fertilizer on Performance of St. Augustinegrass Cultivars

Sustainable lawn care practices include reduced fertilizer and water inputs.  Lawn fertilization with organic fertilizer sources are gaining acceptance in landscape maintenance practices.  Interest in landscape water conservation practices are peaked by shortages in water supply across the United States.  A goal of this study is to measure growth responses of st. augustinegrass [Stenotaphrum secundatum (Walt.) Kutze] ‘Amerishade’, ‘Captiva’, ‘Delmar’, ‘Palmetto’, and ‘Raleigh’ fertilized at three rates of organic fertilizer source while implementing water conserving practices.  An organic fertilizer source was applied at a rate of 100, 200, and 300 kg N ha^-1 per year (low, medium, and high N) split over three applications with the first application in May 2014.  Plots are irrigated using seasonal crop coefficients, minus rainfall, of 0.5, 0.6, and 0.7 for spring, summer, and fall, respectively. A regular cutting height of 7.6 cm was maintained. Spring 2015 greenup ratings in both low N and high N treatments indicate no differences among cultivars.  Raleigh, Palmetto, and Captiva had significantly larger spring greenup ratings than Amerishade, but not larger than Delmar in the medium N treatment.  Leaf stomatal conductance means did not vary by cultivar.  Density, color ratings, and soil nutrient analysis will be presented.