ATLANTA, GA. May 25, 2006 --
In two studies conducted by Texas A&M University and the University of Florida, Nitamin® Steady-Delivery® liquid fertilizer from Georgia-Pacific increased marketable watermelon yield while reducing culls and increasing fruit size. The data also shows that two to three applications of Nitamin Liquid fertilizer during the growing season can be more effective than spoon feeding quick-release fertilizer weekly or adding fertilizer at preplant.
Nitamin, developed by the scientists at Georgia-Pacific, is an innovative slowly-available nitrogen (N) source. The patented Steady-Delivery fertilizer delivers N to crops at a rate they can effectively use throughout the growing season. N is released from Nitamin by the activity of soil microbes, which are most active at temperatures that are optimal for plant growth. This helps to ensure that watermelon plants get the N when it is needed most - during the period of rapid vine growth and fruit development.
In the Texas A&M University study, conducted in 2005 by Dr. Russell Wallace, Texas Cooperative Extension vegetable specialist at the TexasAgriculturalResearch & ExtensionCenter, Nitamin Liquid increased total yield and marketable yield compared to urea. The highest yield of 230 cwt/acre occurred when Nitamin was applied as a split application compared to single applications of either Nitamin or urea, which produced yields of 220 cwt/acre and 210 cwt/acre, respectively (See Figure 1). Yield differences between fertilizers were greatest at the highest N rates, and split applications of Nitamin at 80 and 120 lb. N/acre increased average fruit size compared to the 120 lb. N/acre urea treatment.
“The soil in our Texas study had high clay content and high cation exchange capacity (CEC) making it likely that split Nitamin applications increased plant available nitrogen,” said Dr. Wallace. “Plant vigor ratings and vine length measurements in late June and early July showed that Nitamin plants got off to a faster start which may have resulted in earlier fruit set and increased fruit size.”
Figure 1
The University of Florida study, led by Dr. George Hochmuth, professor of Horticultural Sciences at the IFASNorthFloridaResearchCenterin 2005, showed that Nitamin Liquid produced the highest yield when 75% of the total N was injected through the irrigation system bi-weekly during the first half of the growing season. The yield increase from the injected Nitamin treatment over the ammonium nitrate (AN) treatments ranged from 54 to 76 cwt/acre. The injected Nitamin treatment also tended to have fewer cull fruit than any AN treatment or Nitamin applied as a single application. Nitamin applied as a one time application before planting produced lower yield, and this application method is not recommended for soils with over 90% sand. However, Nitamin applied through the irrigation system in multiple injections resulted in an 8.5 ton yield increase compared to the single pre-plant application. The soil in this study was highly leachable (containing 96% sand and low CEC) making split applications a necessity.
Nitamin yielded good results when a portion of the N was applied at planting and then in three additional injections during the growing season. The scaled back Nitamin application schedule outperformed 12 weekly injections of AN even though the last Nitamin application was made seven weeks after transplanting, ending five weeks earlier than the ammonium nitrate treatments. The results from this watermelon trial demonstrate that injecting Nitamin using a shortened application schedule can increase yield and improve quality compared to spoon feeding ammonium nitrate over the growing season (See Figure 2).
Figure 2
Effect of nitrogen source on watermelon yield and quality- University of FL, Live Oak, FL. (2005)
Total Season Yield (cwt/acre) by Treatment
Ammonium nitrate (injected 12 times - 150lb N/ac)
Marketable: 404; Cull: 30
Nitamin Liquid (preplant - 150lb N/ac)
Marketable: 311; Cull: 24
Nitamin Liquid (injected 3 times - 150lb N/ac)
Marketable: 480; Cull: 7
LSD 0.05 (marketable 87; cull NS)
Jim Wargo, research agronomist with Georgia-Pacific says,“These results from Texas A&M Universityand the University of Florida confirm that Nitamin is an effective fertilizer on watermelons, compared to conventional N sources such as urea or ammonium nitrate. In addition to improving crop quality and production, Nitamin requires fewer applications compared to spoon feeding ammonium nitrate. The result is more efficient watermelon fertilization, even in highly leachable soil.”
Experiment Details
Texas A&M University : The soil at the trial site was an Amarillo clay loam (47% sand, 20% silt and 33% clay) with 0.9% OM, pH 8.1 and CEC 16.5. Core samples were taken pretreatment from 6” to 8” depth and showed 8 lb. NO3/acre were available in April 2005. The test plots were treated with Prefar 4E herbicide and other standard practices were used for disease and pest control in addition to weeding by hand. The plot size was 16.75’ x 25’ with four replicates in a Randomized Complete Block design. The plots were transplanted with three week old Sugar Baby watermelon seedlings on June 9 and drip irrigation was used as needed. Harvest occurred once on August 9. Other variables measured were vigor, rated on July 10 and August 4, and vine length on June 28.
The treatments included urea broadcast and incorporated prior to planting (PP) at rates of 80 and 120 lb. N/acre, Nitamin Liquid applied all at planting (AP) or as split applications AP and just before vine run on June 27, at rates of 40, 80 and 120 lb. N/acre. Nitamin was applied by hand to open trenches 4” deep and 4” to the side of each row with a pressurized backpack sprayer.
University of Florida: The plot soil consisted of Lakeland sand (96% sand, 0% silt and 4% clay) with pH 6.0 and organic matter < 1.0% with high soil phosphorus. The plots were formed with black plastic mulch and fumigated with methyl bromide: chloripicrin at 400 lb/acre. The test area was drip irrigated to maintain a soil moisture of -8 cb to -12 cb measured by a tensiometer at 6” soil depth. This resulted in irrigation periods of 15 minutes twice/day from planting until May 10, 2005, 30 minutes twice/day from May 10 to 26, and 38 minutes twice/day through harvest. Mardigras watermelon transplants were planted on March 10 in a single row with 36” spacing. The experimental design was Randomized Complete Block with four replicates for each treatment in 8’ x 35’ plots.
The treatments included ammonium nitrate (AN) and Nitamin Liquid applied at different rates and times. Nitrogen rates were 105, 150 and 188 lb. N/acre for Nitamin and 150 and 188 lb. N/acre for AN. AN was applied through weekly fertigation for 12 weeks with 25% of N applied to the plot pre-plant. All three Nitamin rates were applied to the plot prior to planting and incorporated before plastic mulch was laid. An additional Nitamin Liquid treatment (150 lb. N/acre) was injected through the irrigation system in three bi-weekly applications beginning three weeks after planting. Twenty-five percent of the N was applied to the plot before planting and the remainder was applied in three equal applications of 25% on each of the application dates.
Georgia-Pacific Resins, Inc. (GPRI) is a wholly owned subsidiary of Georgia-Pacific Corp., and is a market leader in chemical products for the paper, pulp and building products industries, as well as other industrial manufacturing processes. GPRI has been a major raw material supplier to leading fertilizer producers for over 20 years and has over 40 years of experience with urea-based polymer technology. GPRI operates 15 manufacturing facilities throughout the United States. The company also has plants in South Americaand a manufacturing presence in South Africaand China. The company's headquarters is located at 55 Park Place, 16th Floor, Atlanta, GA30303. For additional information, please visit the company’s web sites http://www.gp.com/chemical/ and http://www.nitamin.com/ or call the Nitaminhotline at 866-2nitamin.
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*The University of Florida and Texas A&M University do not endorse Georgia-Pacific, Nitamin, or the use of Nitamin.
Nitamin is a registered trademark and Optimal Nitrogen Diet and Steady-Delivery are trademarks of Georgia-Pacific Resins, INC.
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