The Orchard Ecosystem: Haphazard Mulching

by Michael Phillips

The following excerpt is from Michael Phillips’s book The Holistic Orchard: Tree Fruits and Berries the Biological Way (Chelsea Green Publishing) and is reprinted with permission from the publisher.

I’m a guy who likes to take the concept of diversity to extremes. Establishing an orchard intermixed with all sorts of other plants and bugs is a healthy thing to do. We get an especially good start on the diversity highway by being wantonly diverse about how we manage the understory, meaning the ground and plantings at the base of our fruit trees. It’s time to introduce those of you on the straight and narrow to haphazard mulching…or as mom might say, being somewhat less than neat.

I know, I know. You have particular ideas about how often the lawn should be mowed. That all trees shall be in a straight line. That mulch should be applied uniformly and look tidy. That one dandelion uninvited is an abomination. Well, it’s time for you to lighten up! The appearance of your orchard isn’t about you. Its about the biology, stupid (to paraphrase a political inanity). It’s about a full smorgasbord of varied tree nutrition to be explored and utilized by tree feeder roots. Life thrives in a diverse environment. Try to let go of cultural notions of a manicured garden, especially with your fruit trees. You can find a way to please the neighbors while accommodating principles of health and diversity. Seek the middle ground, and then, as you see better and better fruit, you can come on board completely. Everything is a process, including the orchardist.

Feeder roots of healthy fruiting plants seek nutrients in the fungal duff zone. Organism consuming organism in the vicinity of these roots makes available the right sort of nitrogen and other balanced nutrition. illustration: Copyright 2011 Elayne Sears

Our goal, plain and simple, is fungal duff—that litter layer where mineralization and humification take place. Other plants will grow beneath our trees, certainly tufts of grass, but the density of these other species will be thin, essentially patches of green in between ramial wood chips, piles of shredded leaves, rotting hay, and compost smatterings. The preponderance of all this fungal food is what drives the fungal dominance we want for healthy trees and berries.

Recognizing what makes for acceptable orchard mulch is important. We have defined ramial wood chips, but nevertheless I  know  landscape  notions are going to enter in here and confuse some of you. The arrays of familiar choices at the home and garden center generally do not cut it from a biological perspective. Bark mulch comes from softwood logs, for the most part, and therefore comes rich in tannic compounds that once protected standing evergreen trees from decay. Guess what? Tannins will suppress healthy growth in garden and orchard alike. Dyed bark mulch lifts biological ignorance to a whole new level—mulch that is “pleasingly red” instead of “earth-toned” is that way because of toxic dyes. You would knowingly treat the precious soil this way? Bulk wood chips in a bag, often cedar, sometimes hemlock, are a brown rot phenomenon. Sawdust comes with far too much carbon relative to nitrogen, as does uncomposted horse manure bedding. Let either rot for a few years and it’s a whole different story, but applied fresh beneath the trees? No, no, no. And as for some sort of landscape cloth beneath the mulch that keeps volunteer plants at bay? Forget about it. Synthetic fabrics create a bacterial environment beneath that “weed-protected” surface; meanwhile, mulch decomposition above slows to a standstill and no longer replenishes organic matter in the soil. The ground beneath compacts like cement. There’s a direct correlation here: Human notions of neatness are rarely biological! Organic growers want ramial wood chips and ramial wood chips alone—applied directly to the living earth—for a woodsy mulch.(16)

Your typical haphazard guy delivering ramial wood chip mulch in typical haphazard fashion. Photo by Frank Siteman; Copyright Michael Phillips

Haphazard basically means you don’t do everything the same all at the same time. Just like you, feeder roots like an array of nutrient choices and environments. The reception found beneath fresh ramial wood chips is different from that beneath a one-year-old pile or a two-year-old pile or the remnants of a three-year-old pile. All are worthy, just offering slightly different available nutrients and soil food web happenings. The same goes for a rotting hay bale or randomly piled straw. Both of these grassy mulches increase the level of fungal predators—the  good  nematodes!—which in turn makes available the healthier form of nitrogen (we’ll be distinguishing ammonium from nitrate sources ahead) to our fruit plants. Hay provides a good charge of potassium as it breaks down as well—potassium being one of the nutrients taken away when we harvest a full crop. All told, levels of both macronutrients and micronutrients are found to be consistently higher in the leaves of fruit trees that are mulched. The ability to hold moisture in the soil is yet another huge benefit of mulch, especially where the summer months get dry. And often hot: Soil temperatures are moderated considerably by a mulch cover.

Mulch can be thought of as “shade” as well in that it suppresses an excess of competing plant species. This can be especially important during those first five years or so when a young tree needs to grow wood structure.(17) I place a ring of peastone right up against the trunk of my young trees to keep that zone open and drier for many years to come.(18) Small-sized gravel (screened to 3⁄8 inch) does the trick, about 3–4 inches in depth, placed as a 24- to 30-inch circle with the tree right in the center. Beyond this goes your choice of mulch, replenished as necessary, creating an outer ring within which a young tree can take off . The full-sized tree will eventually shade the ground at its feet more completely, helping to keep a sod cover from filling in this fungal-directed space. We’ll be looking at certain herbs and flowers to add here once the trees come into their own.

Ramial wood chips can be put down anywhere from 2–8 inches deep. Perhaps this year I have enough wood chips to dump a wheelbarrow load or even a full tractor bucket on the south side of every tree, keeping it piled thick rather than spreading it out far and wide. Hay bales randomly go on another side of heavy- cropping trees.(19)  The next year that ramial dump goes to the north side…or the east side…or the west side, being rotated so different stages of decomposition can be found beneath every tree throughout the orchard. I watch understory plants shift from season to season, knowing that spiders and predatory ground beetles will find new homes as they move about as well. Spreading woodsy compost in the fall suits this haphazard pattern. The fungal duff stands renewed and healthy, ready and willing to pump out the fruit of our desire.

Let’s pause just a moment to consider the conventional alternative.(20) And I’m bringing this up only because I know some well-intentioned souls have asked me in the past if it’s okay to use herbicides when growing fruit organically. (We’re all learning at our own pace.) These chemicals directed at unwanted species of plants have a number of biological consequences. Decomposing fungi are destroyed and thus are no longer able to sequester atmospheric carbon into humus. The mycorrhizal network that trans- ports nutrients and water to the rhizosphere (the zone around the roots) is broken. Now the tree “requires” inorganic fertilization—from chemicals, of course— to make up for this loss. Disease becomes a far bigger problem when nutrition is no longer balanced and scab-infected leaves from the season before lie on top of biologically dead ground. Honestly. Herbicides are part of the mind-set that we are changing here. Choose a diversity of mulches instead.

Notes

  1. Good question: Does it matter if the ramial chips are fresh, or do these need to be aged as well? I currently have no reason to say one way or the other. We’ll be talking about using this same treetop source as part of an orchard compost pile. Chips piled to begin decomposition on the forest edge might actually pick up a mycorrhizal spore component (being in the vicinity of extant tree roots) over the course of a year or two. But I also use freshly chipped ramial wood directly in my orchards when it becomes available in late fall and in earliest spring when I work up cordwood. I figure those ramial chips are functioning biologically like humus on a deciduous forest floor by the time the growing season begins in earnest.
  2. The Agriculture Canada Research Station in Summerland, British Columbia, has done extensive studies as to the effect of different kinds of mulches on apple trees. Cross-sectional trunk diameter of fruit trees is up to 35 percent greater after using a biological mulch versus unmulched control trees. Come the fruiting years, cropping averaged about 15 percent more fruit per tree. The overall health and vigor of the trees with mulch were noticeably increased as well.
  3. The openness helps in deterring borers as well as bark-chewing rodents. The dryness lessens the chances of Phytophthora root, crown, and collar rot fungi establishing. Growers in the Piedmont regions of the southeastern United States especially want to keep the base of young trees clear of dead organic matter to deny southern blight fungi a food resource right by the trunk.
  4. Here we should give some consideration to the bumblebee queen. A hay bale placed out in late summer is in place when spring arrives and queen bumbles awake to search for a nest site. A semi-intact hay bale offers ample opportunity for this, particularly if field mice made a nest in that bale in the fall, leaving a cozy start for an eager queen. Come fall she and her progeny will have passed their season…and now that fairly rotten bale can be spread apart where it sits to break down even further.
  5. I’m going to state this just once: The word conventional used to describe orchard methodology really bugs me! Chemical proponents assume that spray choices of the last hundred years represent the norm; that not to use chemicals to grow fruit is somehow unconventional. The right words

About the Author

Michael Phillips is an orchardist and organic orchard consultant in addition to his roles as writer, farmer, carpenter, and speaker. Michael lives on Heartsong Farm in northern New Hampshire, where he grows apples and a variety of medicinal herbs. Michael is the author of Mycorrhizal Planet: How Symbiotic Fungi Work with Roots to Support Plant Health and Build Soil FertilityThe Apple Grower; and The Holistic Orchard.
His Lost Nation Orchard is part of the Holistic Orchard Network. He also leads the community orchard movement at www.GrowOrganicApples.com.

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