A lack of nitrogen is often a culprit in failure to thrive, which is why leaving grass clippings or mulched leaves behind is such a great idea. A mulching mower is a terrific garden tool, both for clippings and to help leaves from healthy trees to decompose. Don’t bag, rake or burn it – mulch it!
Other human actions impact tree health. Your tree’s roots extend far beyond the dripline, so allow adequate growing areas for a good root structure. Don’t pave over the surface right up to the trunk. Installing other plants under the tree canopy also creates competition for nutrients and water.
When Tree Fertilization May Be Appropriate
Within the soil, two distinct categories of problems can occur. Not enough of a nutrient (deficiency) or too much of one (toxicity) can stunt growth or invite susceptibility to pests or diseases. In the Kalamazoo area, our most typical problems relate to the pH (acidity and alkalinity) of the soil, imbalance in specific macronutrients and micronutrients, and salinity.
Other conditions that may warrant adding fertilizer to the soil would be severe damage from pest or disease, or situations where roots are disturbed or damaged severely from trenching, digging, or compaction by earth moving equipment. In those cases, the tree may need an extra boost of nutrients to help it survive.