Trees: What's Going on Down There?

Photograph by Vanessa Tortolano

What lies below the ground is a complex myriad of networks; communities; exchange systems; and a small constant struggle for space, nutrients, water, and survival. We often think of this as a void with some nonpersonal disregard, almost not really thinking of it at all until we want to move it, use it for our own benefit, or we have a problem with the surface. Once we’ve broken ground, we find roots; small rodents; insects; rocks (cement or debris); nutrients; chemicals, possibly both manmade and plantmade; and organic matter, like twigs, leaves, and decaying plant fragments. Not to mention the millions upon millions of bacteria and fungi greasing the wheels and literally feeding this massive metropolis.

This system is so intricate that it resembles a tornado if drawn out with arrows circling back on themselves and off in wild directions. Even today, we are still learning new interactions and symbiotic or beneficial relationships. What’s for sure is soil is better fed naturally and left alone as much as possible.

It’s important to distinguish soil from dirt. Whereas soil is a teeming mixture of minerals, organic matter, animal and vegetable life, moisture, mycelium, bacteria, and gases/chemicals, dirt is often treated as a lifeless medium to which must be added ample amounts of water and soluble amendments in order to promote growth. The former is meant for survival, and the latter is crying for help.

So how do we attain this lovely myriad of nonstop movement and growth? There are a few small things anyone can apply; however, it may sound contrary to everything you’ve been taught. For example, start avoiding extensive digging or tilling, as it disrupts any of the fungal layer that has started to feed and protect roots, which is also crucial in maintaining moisture in the groundwater, the sustenance of all life on this planet. This fungal layer is far, far from anything bad and, in fact, creates what’s called a rhizosphere, a safe haven and nursery for new roots to carry on their venture into the soil. There are now products on the market to help you add this beneficial mycelium to anything new you plant or to top-dress existing species. Synthetic fertilizers, pesticides, insecticides, and even herbicides can be toxic, suffocating the natural rhythm that wants to inhabit there.

For the surface, consider leaves, straw, small amounts of lawn clippings (nontreated), aerated compost, steel oats can promote quick mycelium, plant debris (somewhat aged is best), and pine needles all topped with nontreated aged bark mulch to keep it safely in place and relieve the city of harmful runoff. These sandwich layers will continue to work for years, adding so much moisture and nutrients that watering demands decrease substantially and weeds either cease to grow or are removed with ease. This can be repeated as frequently as you have material available, just avoiding the crowns of any plant or tree. Compacted, treated dirt is lifeless, hard, and unforgiving in comparison.

Scaling up, let’s talk insects. These little, bitty critters are so crucial to any functioning soil food web that their presence, both in type and numbers, is a direct indication that the community (your soil) is healthy, working, and thriving. Healthy soil can have many hundreds of insects in one square foot, and over 90 percent of them are harmless to humans. The other 10 percent aren’t all bad either, as much of them make up the food source for the rest. When a system is allowed to have such a polyculture, it’s often self-moderated in numbers.

Roots go deep, and when I say deep, it’s much more than you’re probably thinking. Given the right setting, roots can and will far surpass anything you can see above the surface. Tomatoes grown in one season in Madison can have 5- to 6-foot-deep roots. Oaks and some of our larger trees are often mimicked in dimension by 60 to 90 percent below the ground. Soil conditions can drastically alter this, and there are ways to train roots to grow deeper so they are more climatically stable and resilient in the case of drought or storms. Insects are also imperative here, as they create looser soil for these roots to go so deep.

Noninvasive weed species are often seen as evil, but they really do wondrous work for us. Pesky weeds grow quick and die quick, providing loads of organic matter to the soil. They are biodynamic accumulators that make nutrients available to plants that couldn’t access and cycle them back down, creating literal feet of moving nutrients. They often tell us what’s wrong with the soil or missing in the nutrient chain.

Dig less, relax more—what I call lazy gardening—is the act of eliminating your task list; increasing bounty; and shedding labor, cost, and backache. Soil is a living, breathing, and growing metropolis. One we should honor, feed, and respect. It’s home to the bottom of everything we see. Hopefully we shed a bit of light into the darkness so your adventures above are much more fruitful.

Karina Mae is the designer and team leader at Garden Search & Rescue.

Garden Search & Rescue
Madison, WI