We often are asked about fertilizing trees in a deer orchard. This is a very important aspect of managing these special areas for your deer. Just as with forage crops, trees also need the proper nutrients. The questions are what, when and how?
Your trees should not be fertilized the first year; rather the following spring. Fertilizers come in many forms such as granules or “prills,” liquid and spikes. In most cases we prefer to use granular fertilizers, with the exception of some micronutrients. We classify nutrients as macronutrients and micronutrients. It has nothing to do with their size, rather how much a plant needs.
The most common macronutrients are nitrogen (N), phosphorus (P) and potassium (K), also known as potash. In general, N supports leaf and stem growth, P supports metabolic processes and reproduction, and K supports root growth. Fertilizers are labeled with three numbers such as 13-13-13. Each number stands, in general for the percentages of N,P and K.
There are critical micronutrients, especially for nut trees, that include copper (Cu), Zinc (Zn) and boron ((Bo). These are required in very small amounts, and can be toxic if applied at too high a rate!
We strongly recommend you collect soil samples from your feet orchard, and have a soils laboratory analyze them and make recommendations. You should clearly label your soil samples with the designated crop as fruit/nut trees.
Once you have a recommendation for the formulation, you should distribute the fertilizer evenly within the drip line of each tree (the crown edges projected down to the ground). Never put fertilizer witin a foot of the base of the tree. It could damage or kill your tree.
You may know the right formulation, but how much do you distribute around each tree? For trees less than 7 in diameter at the base, spread one pound; for 7-12 in. trees, spread 2 pounds; and for trees greater than 12 in. At the base, distribute three pounds.
What if you cannot get a soil analysis? A very crude recommendation would be 20-10-10 fertilizer.
When should you apply the fertilizer? The best time is just at spring green up for your area.
As to micronutrients, there are various products sold as to be used as foliar sprays. For example, zinc can be supplied as zinc sulfate, mixed 2-3 pounds per 100 gallons of water. Most orchard managers recommend foliar spraying in three applications through the growing season. Zinc can be applied as a granule, at a rate of 2-3 pounds per acre, but it will not be as effective.
Your deer orchard is a long term investment, requiring attention each year to keep it productive. Proper fertilization is a critical part of this program.