|Avocado (Persea americana
French: Avocatier; Spanish: Aguacate; Italian: Avocado; German: Avocado
Added N benefits the avocado almost universally. It is, therefore, regularly applied in four or more dressings annually, often broadcast or preferably via the irrigation system. P and K are applied only when leaf analysis indicates low levels.
Zn deficiency is second to N in its frequency of occurrence. It can be corrected by applying a Zn-containing fertilizer to certain types of soil or as a foliar spray. Foliar application is most effective when spring cycle leaves are expanded. It may be induced or aggravated by application of P-fertilizers or poultry manure.
Fe may be deficient when the crop is grown on calcareous soils or on soils with low oxygen content. The most effective application is chelated iron solution injected into the root zone.
Preferred nutrient forms:
N: as ammonium sulphate, or ammonium nitrate for alkaline soils; urea; calcium nitrate or calcium ammonium nitrate for acidic soils.
P: as superphosphate, before planting; or phosphoric acid, via the irrigation system.
K: as potassium chloride, when Cl in irrigation water is not high; or Potassium sulphate, in high Cl conditions especially when the plants are grafted on the chlorine-sensitive Mexican rootstocks.
Zn: as zinc sulphate, oxide or chelate.
Fe: as chelated compounds.
Present fertilizer practices
N application is based on foliar analysis and the cultivar:
The above amounts should be reduced on certain soils and when N is present in the irrigation water; they should be increased when trees have little new growth and pale leaf color, or heavy fruit set (over 10 t/ha for Fuerte or 15 t/ha for Hass).
GOODALL, G.E.; EMBLETON, T.W.; PLATT, R.G.: Avocado Fertilization. Div. Agric. Sci. Univ. California, Leaflet 2024 (1979)
LAHAV, E.; KADMAN, A.: Avocado fertilization. Intern. Potash Inst. Bull. 6, Worblaufen-Bern, Switzerland (1980)
MARCHAL, J.: Avocado. In: MARTIN-PREVEL, P.; GAGNARD, J.; GAUTIER, P. (eds.): Plant analysis as a guide to the nutrient requirements of temperate and tropical crops. Lavoisier publ. New York (1987)
WHILEY, A.W. et al.: Manage avocado tree growth cycles for productivity gains. Queensland Agric. J. 114, 29-36 (1988)
Author: E. Lahav, Agricultural Research Organization The Volcani Center, Bet Dagan, Israel