The Influence of Fertilizers from Different Nitrogen Sources on Strawberry (Fragaria ×ananassa) Production

The United States is a leading producer of strawberries worldwide, accounting for approximately 30% of the total world strawberry production. While the majority of the U.S. strawberry production is conventional, consumer demand for organic strawberries has been increasing in recent years and interest in organic strawberry production is growing among producers. Hydrolyzed fish fertilizer and sodium nitrate based fertilizer have been used through the fertigation system by organic strawberry growers in Florida during the production season. The two types of fertilizers differ in nitrogen source and release rate as well as contribution to soil biological activity. In this greenhouse study, fertilizers from different nitrogen sources used in organic and conventional production, respectively, were compared in terms of their effects on strawberry growth and yield performance. Plants were grown in 7.6 L pots filled with sandy soil from the certified organic field at Plant Science Research and Education Unit in Citra, FL. Plug plants of two strawberry cultivars SensationTM Brand ‘Florida127’ and WinterstarTM were transplanted on Oct. 30, 2014. The fertilizer treatments included Neptune’s Harvest 2-0-2 with the ingredients of hydrolyzed fish, molasses, and seaweed extract, Gator 96002/3-0-6 0-0 organic liquid blended with sodium nitrate, and a conventional fertilizer 6-0-8. Potassium fertilizer was added in the Neptune’s Harvest and conventional fertilizer treatments to match the amount of both nitrogen and potassium provided by the Gator organic liquid treatment. A randomized complete block design with four replications was used. The fertilizer effect was significant on strawberry early yield, and significant differences in plant growth and fruit yield were observed among strawberry cultivars. Plants fertilized with Neptune’s Harvest 2-0-2 showed higher total fruit yield than Gator 96002/3-0-6 0-0 organic liquid during Dec. 2014. Interestingly, conventional fertilization did not differ significantly from the other two fertilizer treatments. SensationTM Brand ‘Florida127’ showed fewer marketable fruit per plant than WinterstarTM, whereas WinterstarTM exhibited lower average fruit weight during Dec. 2014 to Jan. 2015. With respect to the growth parameters at early stage, WinterstarTM plants demonstrated significantly larger crown, while SensationTM Brand ‘Florida127’ was higher in plant leaf number.