The Kinds of Fertilizers Used in Growing Oranges

Required Nutrients

• Orange trees require the macronutrients nitrogen, phosphorus, potassium, sulfur and calcium in relatively larger amounts than the micronutrients. Macronutrients are also referred to as the essential nutrients whereas micronutrients are essential to growth but are required in less amounts. Micronutrients required for citrus include magnesium, iron, copper, zinc, manganese, molybdenum, boron and chlorine.

Recommended Fertilizer

• Use especially blended citrus fertilizers to fertilize the tree as these contain all the nutrients required for oranges. Select the formulation of 16-8-4 or 16-8-2, as suggested by Jeff Myer in "The Tree Book." These numbers are also indicated as N-P-K where N is the amount of nitrogen, P is phosphorus and K is potassium. Regular fertilizer application is especially important when trees are young. The requirement generally remains the same after the age of 5 years.

Fertilizer Amount

• Fertilize a newly planted tree with about 0.12 lbs. of the fertilizer until the age of one year. Between 1 to 2 years of age, use about ¼ lb. of the fertilizer. Increase this amount to ½ lb. for 2 to 3 year old trees, to ¾ lb. for 3 to 4 year old trees, to 1 lb. for 4 to 5 year old trees, to 1-¼ lbs. for 5 to 6 year old trees and to 1-½ lbs. every year after the age of 6 years. Divide amount in three parts and apply during January, April and August, as recommended by the University of Arizona Extension.

Fertilizing Tips

• Applying fertilizer to the soil is the recommended mode of application though it can lead to loss from runoff and leaching. Foliar application, where the fertilizer is sprayed on the foliage, is also used occasionally. This mode of application is advantageous in overly wet or dry and calcareous soil. Calcareous soils have high levels of calcium carbonate and a pH level of more than 7.0. However, foliage application is not recommended on a longterm basis. Avoid replacing soil application of fertilizers with foliar feeding method.