PIECES OF THE PAST: Reflections on Fertilization

Daniel Cooper Nutrition, Pieces of the Past

Applying fertilizer by hand

By Brenda Eubanks Burnette

In his book, “The Cultivation of Citrus Fruits,” first published in 1926 by The MacMillan Company, H. Harold Hume covers a variety of topics, including the use of fertilizers and the different needs of young trees versus bearing trees. Following are insightful excerpts:


“Young adult trees differ in their fertilizer requirements. Young trees use their food supply in the formation of wood and leaves. For the first four or five seasons they grow vigorously. When the bearing period is reached, a gradual change comes about; the trees do not grow so rapidly, and a large portion of the food supply is diverted to fruit formation. The demands on the trees being different, the food supplied should be different in character. For young trees, the fertilizer should contain about 6% phosphoric acid, 5% potash, and 4% ammonia, while one containing 8% phosphoric acid, 10% potash, and 3% ammonia should be applied to the grove of bearing trees.

“The amounts of fertilizer required depend on the age, size of the crop, the amount of fertility already in the soil, and the amount of nitrogen supplied by the cover crop, if one is grown.

“On poor soils, a half-pound of fertilizer for each young tree should be incorporated with the soil at the time of planting; if the trees are set in winter, an additional pound should be given in June and one-half to three-fourths pound in early September. The second year, the amount should be increased. Each succeeding year the quantity must be augmented, never allowing the trees to become stunted or to assume a starved appearance. It is better to anticipate their needs than to wait until they are injured. It is usually better to estimate the amount of fertilizer on the basis of so many pounds for each tree, rather than to figure requirements on acreage basis.

“When the trees begin to fruit, the formula should be changed to one for fruit; and the formula for growth may be re-applied whenever it is seen that the trees are not adding sufficient new wood. Trees in Florida producing 10 boxes of fruit should receive about 30 to 50 pounds each. This same proportion may be preserved for each additional 10 boxes of fruit.”

Hume goes on to note that “When fertilizing for growth in young or old trees, greater results may be obtained from a given amount of fertilizer applied so as to take effect in early spring than that given at a much later time.” As a grower once put it, referring to making growth, “An application of 1 pound of fertilizer before July 1 is worth 2 applied thereafter.”

Hume closes his chapter on fertilization with this: “The carrying of a crop of fruit through the fall and winter months is a heavy drain on vitality. Some persons think that when the crop is grown and begins to color it is no further burden on the tree. This is not the case. It still requires plant food to keep it in good condition. In this period the trees must also prepare for and produce another crop of bloom, and the double burden must be provided for by fertilizing. Nitrogen particularly is needed; it is often good policy to apply, late in August, 2 to 3 pounds of nitrate of soda to each tree carrying 10 or more boxes of fruit, if the weather conditions are right. Often this plan is of great assistance in securing uniformly heavy crops from year to year. After all, the wise grower watches his grove and crops closely and gives fertilizer or withholds it as the condition of the trees may indicate. One of the compensations in growing citrus fruits on poorer lands is that the growth of the trees and the quality of the fruit are more definitely under the control of the grower than if the land is well supplied with plant food. It is true of citrus fruits that they reflect in their character and quality the wisdom and care of him who produces them.”

Now that’s a reflection to consider!

Brenda Eubanks Burnette is executive director of the Florida Citrus Hall of Fame. Pieces of the Past is presented in partnership with Florida Southern College’s McKay Archives Center in Lakeland.

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