Nitrogen Leaching from Young Florida Citrusby Brian J. Boman, Univ of Florida, Ft. Pierce, United States,
Document Type: Proceeding Paper
Part of: Management of Irrigation and Drainage Systems: Integrated Perspectives
Sixteen buried drainage lysimeters were constructed from 2300 L polyethylene containment basins for the study. The lysimeters were 2.1 m in diameter by 0.8 m deep and were filled with Oldsmar fine sand series soil. 'Midsweet' orange on Carrizo citrange rootstock trees were planted on May 5, 1991. Water applications with microsprinklers were measured with totalizing flow meters. Water samples were taken weekly by applying a vacuum to a ceramic cup system located in the bottom of the lysimeters. The quantity of nutrients leached was determined by multiplying the quantity of leachate by the concentration of the constituent nutrient in the water sample. Fertilization treatments included conventional application of dry fertilizer at 6 week intervals, 17 weekly fertigation applications, and single applications of 2 different controlled-release materials. The traditional and fertigation treatment trees each received 135 g tree-1 of nitrogen (N) while the controlled-release treatment trees each received 60 g tree-1 of N. Each fertilization treatment was replicated in 4 lysimeters. All treatments having less than 2.5% of the applied N leached. However, since higher rates were applied to the traditional and fertigated trees, these treatments had more N leached. The total N leached by the fertigated trees was about 2 times more than for the controlled-release. The traditional broadcast applications resulted in about 2.3 times more N leached than the slow release materials. About 60% of the total N leached with the slow release fertilizer occurred during the last week of July when over 200 mm of rain fell. Very little N was leached from the controlled-release or traditional fertilization treatments after the heavy rains ceased in the first part of October. No difference in three growth among fertilizer treatments was measured.
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