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Response of Microsprinkler‐Irrigated Navel Oranges to Fertigated Nitrogen Rate and Frequency
Author(s) -
Kusakabe Ayako,
White Scott A.,
Walworth James L.,
Wright Glenn C.,
Thompson Thomas L.
Publication year - 2006
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2005.0346
Subject(s) - fertigation , citrus × sinensis , irrigation , loam , drip irrigation , horticulture , rootstock , agronomy , calcareous , orange (colour) , rutaceae , mathematics , environmental science , botany , soil water , biology , soil science
Microsprinklers allow precise control of irrigation water applications and offer the potential for higher efficiency of water and fertilizer use compared with flood irrigation. A field experiment was conducted during 1999–2002 in central Arizona (AZ) to evaluate effects of various N rates and fertigation frequencies on fruit yield and quality, leaf N concentration, and residual soil N of ‘Newhall’ navel oranges ( Citrus sinensis ) on ‘Carrizo’ citrange ( Porcirus trifoliata x Citrus sinensis ) rootstock (planted in 1997) grown in a Gilman (coarse‐loamy, mixed, superactive, calcareous, hyperthermic Typic Torrifluvents) fine sandy loam. The experiment included nonfertilized control plots and factorial combinations of three fertigation frequencies (27, 9, and 3 applications annually) and three N rates (68, 136, and 204 g N tree −1 yr −1 ). Maximum yields occurred at N rates of 105 to 153 g N tree −1 yr −1 for the fourth to the sixth growing seasons. The yield‐maximizing N rates were equivalent to 17 to 34% of currently recommended N rates for citrus grown in AZ. Fruit and juice quality did not show significant response to N rate or fertigation frequency. Leaf N concentrations at yield‐maximizing N rates were above the critical leaf tissue N range of 25 to 27 mg g −1 , indicating that this range may be too low for these ‘Newhall’ navel orange trees. During all three seasons, higher residual soil NO 3 concentrations resulted from the highest N rate. Our results suggest that optimum N rates for microsprinkler‐irrigated ‘Newhall’ navel oranges in AZ are lower than currently recommended N rates.