NITROGEN LEACHING, N UPTAKE EFFICIENCY AND WATER USE FROM CITRUS TREES FERTILIZED AT THREE N RATES

SYVERTSEN, J. P.

Abstract


Four-yr-old 'Redblush' grapefruit (Citrus paradisi Macf.) trees on either 'Volkamer' lemon (VL, C. volkameriana Ten. & Pasq.) or sour orange (SO, C. aurantium L.) rootstocks were transplanted into eighteen 2000 gal drainage lysimeter tanks filled with native Candler sand, irrigated similarly and fertigated weekly with nitrogen (N) application rates of about 0.3, 0.7 or 1.6 lbs N/tree/yr during a 2.5 yr period. A lysimeter tank with no tree also received the intermediate N treatment. N concentration in the drainage water increased with N rate and exceeded 10 ppm for trees receiving the highest rate and also for the no tree tank. Leachate N concentration and total N recovered was greater from trees on SO than from those on VL. Average N uptake efficiencies of intermediate N rate trees on VL was 68% of the applied N and 61% for trees on SO. Canopy volume, water use and leaf N concentration increased with N rate, but rootstock had no effect on leaf N concentration. Fruit yield increased with N rates except that yields of intermediate and high N rate trees on SO did not differ. Trees on VL developed larger canopies, more fibrous roots, used more water and yielded more fruit than trees on SO. Based on growth, fruit yield and N leaching under these conditions, 1 to 1.2 lb N/tree/ yr was appropriate for trees on the more vigorous VL rootstock but these rates were 22 to 69% too high for trees on SO.

Keywords


citrus paradisi; grapefruit; c. volkameriana; 'Volkamer' lemon; c. aurantium; sour orange; canopy growth; fruit yield; evapotranspiration; leaf nitrogen

Full Text:

PDF

Refbacks

  • There are currently no refbacks.


Proc. Fla. State Hort. Soc.     ISSN 0886-7283