Written Paper

Frequent fertigation does not affect citrus tree growth, fruit yield, nitrogen uptake, and leaching losses  [2001]

Syversten, J. P. J. L. Jifon

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Effects of fertigation frequency on tree growth, yield and nitrate leaching losses were studied in 1999-2000 using 6-year-old 'Hamlin' orange (Citrus sinsensis [L.] Osb.) trees on Single citrumelo (C. paradisi Macf. x Poncirus trifoliata [L.] Raf.) rootstock growing in 7.6 m³ lysimeter tanks filled with native Candler sand. All trees were irrigated frequently (except for rainy periods) and fertigated with ammonium nitrate at similar annual rates of N that varied from 324 to 462 g of N per tree. Three groups of six trees each were either fertigated with every irrigation (about 80 times per year), fertigated about 37 times per year, or about 12 times per year. There was not effect of fertigation frequency on leaf nutrient concentration, canopy size, fruit yield, or juice quality. Variability in tree size resulted in larger trees using more water, taking up more N and yielding more fruit than smaller trees. The average concentrations of N in the drainage water ranged from 27 to 86 mg•L⁻¹ but such variations were not related to total amounts of N leached below the root zone because of the smaller drainage volumes from below larger trees. Nitrogen uptake efficiencies ranged from 24 to 41% of N applied, but there was not effect of fertigation frequency on the amount of N that was leached or taken up by trees. Thus, these trees received more than sufficient N regardless of fertigation scheduling and there was no significant reduction in N leaching losses wh
en fertigation frequency was increased 12 times per year to 80 times per year.

From the journal

Proceedings of the ... annual meeting of the Florida State Horticultural Society

ISSN : 0886-7283