The 2009 ASHS Annual Conference

The agricultural soils of Maryland are relatively sandy resulting in an environmental concern about nitrate leaching into the sensitive ecosystem of the Chesapeake Bay. Improved efficiency in the use of available nitrogen may lead to reductions in run-off and leaching, and be financially advantageous to growers.  This research examines effects of nitrogen applied at reduced rates in combination with Acadian  Ascophyllum nodosum seaweed extract on yield and nitrate levels in the petioles of watermelons.  Replicated trials on Crimson Sweet watermelons were established at the Lower Eastern Shore Research and Education Center (LESREC near Salisbury, MD, soil type: Fort Mott loamy sand), and the Central Maryland Research and Education Center (Upper Marlboro, MD, soil type: Adelphia fine sandy loam) using a randomized complete block design with 5 replications.  Treatments included nitrogen applied at planting at rates of 100 and 150 pounds/acre, with and without Acadian Ascophyllum nodosum seaweed extract  applied at 1.5 quarts/acre 2 weeks after transplanting, at bloom, at fruit set, approximately two weeks after fruit set, and 4 weeks after fruit set. Nitrate-N petiole-sap measurements were taken with a Cardy meter starting near fruit set and every 7-10 days until harvest.  Yield data consisted of melon weight and number. Nitrate petiole sap measurements in 100 lbs. N+seaweed extract treatment were similar to those from 150 lbs. N treatments.  Treatments with 100 lbs N and the addition of seaweed extract showed yield results similar to those from the 150 lbs. N plots.  Acadian Ascophyllum nodosum extract treatments allowed for reduced nitrogen applications while maintaining yields in watermelon.