Bone Meal & Orange Trees

Bone Meal

• Bone meal is made from finely ground animal bones, usually sourced from slaughterhouse waste, and is often treated with steam to prevent the spread of pathogens. Although bone meal is primarily considered a source of phosphorus, it also supplies significant quantities of nitrogen and calcium. The typical nutrient analysis of bone meal is 5-12-0, or 5 percent nitrogen, 12 percent phosphorus and 0 percent potash by weight; it also contains 22 percent calcium by weight.

Using Bone Meal

• Bone meal is expensive in relation to its quantity of major nutrients. It would be cheaper to supply nitrogen with synthetic fertilizers, phosphorus with soft rock phosphate and calcium with agricultural lime. The primary advantage of bone meal is that it is an organic source of immediately available phosphorus, while rock-based phosphorus amendments release their nutrients slower. If you are preparing soil several months before planting your orange trees, it would be more economical to use rock phosphate. If you are almost ready to plant your trees or for trees that are already established, bone meal is a good choice.

Phosphorus for Orange Trees

• Oranges and most other citrus fruits do not have particularly high phosphorus needs. If your soil is relatively fertile, you may get acceptable yields without any phosphorus fertilizer. If you are concerned about your soil's native supply of phosphorus or if you want to do all you can to ensure optimal yields, apply about 1 pound of phosphate to each tree every three years. Bone meal is 12 percent phosphate by weight, so you would need to apply about 8.3 pounds of bone meal to supply 1 pound of phosphate per year. Spread the bone meal around the base of the tree and gently stir in into the top few inches of soil.

Nitrogen for Orange Trees

• Orange trees require high levels of nitrogen. If your trees are not producing as well as you would expect, the problem is most likely a nitrogen deficiency. Orange trees need about 1.5 pounds of nitrogen per year. Bone meal is 5 percent nitrogen by weight, so you would need 30 pounds of bone meal per tree per year. This would be impractically expensive, but more importantly, this much bone meal would supply far too much phosphorus. Consequently, bone meal is not an appropriate nitrogen source for oranges.