Sandia

2007 Slow Release Nitrogen Fertilizer Study in Watermelon
Investigator:

Mark Seitz, Extension Area Agent – Commercial Horticulture & Marketing North Carolina Cooperative Extension – Jones County Center Harvest Moon Farm Herb and Tyler Griffin Pollocksville, NC

Jones County Center 110 South Market Street P. O. Box 218 Trenton, NC 28585 Phone 252.448.9621 Fax 252.448.1243

Cooperators:Introduction: Commercial production of watermelon generates a significant amount of income for North Carolina farms. In 2006 North Carolina ranked seventh in the US in total production of watermelon with an estimated value of $7.3 million dollars.1 The climate of North Carolina is well suited to the production of watermelon. Watermelon is a heat tolerant crop in the Cucurbitaceae family.Watermelon is generally grown on very sandy soils across North Carolina. Nitrogen fertilizer applications on these soils are highly susceptible to leaching in wet years, or volatilization in dry years, which can leave the crop with an insufficient amount of nitrogen to allow the crop to reach full maturity. Farmers routinely express concerns about the availability of nitrogen for vegetable crops grown onsandy soils. Traditional fertilizers such as ammonium nitrate and calcium nitrate are susceptible to leaching and volatilization in extremely wet or extremely dry conditions respectively. Slow release nitrogen fertilizer technology has been available for many years. However, most farmers believe marketable yield in these crops cannot justify the additional cost of this slow release technology. Itis for these reasons that an on-farm slow release nitrogen fertilizer demonstration was initiated in April 2007. Methodology: The objective of this test was to determine if there was any significant difference in the number of marketable fruit per acre in watermelon using slow release nitrogen fertilizers as compared to calcium nitrate. Four nitrogen fertilizer sources were selected for use in thistest. Three slow release nitrogen products: JMAXX (47% N), Super Urea (46% N), Nitamin (31% N) and calcium nitrate (15.5% N) were used. The plots were not replicated. A single, 100 pound per acre application of nitrogen and a split application totaling 100 pounds per acre (40 lbs / 60 lbs – split) were tested.
North Carolina State University and North Carolina A&T State University committhemselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

1

North Carolina AgricultureStatistics 2006. North Carolina Department of Agriculture and Consumer Services, Raleigh, NC.

1

The plots were planted from transplants on April 25, 2007 across 11 rows of watermelon on 42” row middles. Plots 1 through 4 were 60 feet long and plots 5 (single application) through 9 (split application plots) were 30 foot long. In each test, nine (9) rows were planted to the variety CrimsonSweet and two (2) rows in each plot were planted to Royal Sweet. There were 17 plants per 60 ft row in the single, 100 lb / acre plots and eight plants per row in the plots treated with the split application of nitrogen. The granular and liquid nitrogen fertilizers were measured and applied in a side dress manner. The granular products: JMAXX, Super Urea and calcium nitrate were applied by hand andcultivated into the soil in a band adjacent to each row. In each plot the following amounts were applied per row to equate to 100 lbs per acre of actual N: JMAXX - 1.2 lbs per row; Super U – 1.2 lbs per row; CaNO3- 3.6 lbs per row. In the Nitamin (liquid) plots 835 mL was applied to each row in the 60 foot long plots. In the plots where the nitrogen was applied two times, 167 mL was applied on...