Fertile Mulching: Why It Works So Well
by Gary Kline
Fertile Mulching is the name of a gardening technique developed by Black Lake Organic that has proven unexpectedly effective in the revival and health maintenance of trees, shrubs and other perennial plants. We can say this because of the amazing results reported by customers who have used this method. But just what is the explanation for the incredible growth response we and customers see when Fertile Mulch is applied around plants?
Starting out, I want to be clear that we are talking about something more, much more, than simple mulching. And, for that matter, more than simply fertilizing. We are talking about a synergy of materials and processes where one and one equals five. Recognize too, that the technique was developed for treating plants already established (or in the ground), but you could also adapt it for use at the time of planting, when you would have the opportunity to mix some of these ingredients down in the root zone.
Giving credit where credit is due, I have to acknowledge that the inspiration for this method comes from “The Dirt Doctor”, Howard Garrett, and his 1995 book The Dirt Doctor’s Guide to Organic Gardening. However, I suspect that Garrett got the ideas or information from others who are not specifically acknowledged in his book. I have to say too, that Garrett impressed upon me that oxygen is a fertilizing nutrient, and getting it to the roots is vitally important.
At the time I first formulated my version of Garrett’s method, I had some unanswered questions about how fertile mulching worked and what the different components contributed. I think I’ve since figured most of that out, and that’s what I want to tell you about because this, truthfully, is a major contribution to horticulture and to the successful growing of plants in a way that makes the most of nature’s actors in concert. It does so without doing harm. Indeed, Fertile Mulching makes a hugely positive contribution to environmental health, if for no other reason than it potentially eliminates the need to routinely use toxic pest and disease control sprays in orchards and landscapes. Try it, you’ll like it.
What’s involved here is the principle of nutritional pest control whereby pest deterrence is achieved through creation of internal resistance or plant immunity. However, before it can work, gardeners have to be persuaded to switch paradigms. In other words, you’ve got to become a believer, if you aren’t already. I find that people get this (i.e., it clicks) when I point out that it’s the same thing that goes on with the human immune system.
The next step of the paradigm conversion happens when you get the “mineral message”. Immunity has largely to do with vitamins and enzymes, complex regulatory compounds that are powered mostly by various trace minerals. If you’ve got them, great; if you don’t, you’re sick, and vulnerable to attack by pathogens and parasites. The same goes for that sickly apple tree out in your backyard. Ultimately, what makes this system work is that we get the required nutrients for optimal nutrition and health into the plant. Pests and pathogens are repulsed by the taste of health. But you get better taste, plus more and better fruit. Such a deal!
Other growth factors, of course, are at work as well. All higher plants need ample sunlight, warmth, water (but not too much), air (O2, CO2 and, ultimately, N) and anchorage (a good, loose medium to sink their roots into). But if all those things are in reasonably optimal status, the thing that makes the greatest difference between superb and marginal growth is nutrition. Plants, too, are what they eat, or are fed.
What the mulching system does is help to create an optimal soil environment for the plant’s roots, but also for all the cooperating and facilitating soil biota (microbes, earthworms, etc.) that process nutrient-supplying materials and more or less feed them to plant roots, a la nature. Wide temperature fluctuations are prevented and moisture and air supply held more steady.
The BLO Fertile Mulching System is described in Gardening Information Leaflet (GIL) No. 4 that is available at the store and on the BLO website. As GIL No. 4 points out, the old wisdom about roots extending out to the dripline is generally incorrect. With most trees, the roots extend far beyond the dripline, and it is out on the fine root tips where most of the feeding takes place. That’s where you want to put most of the fertilizer and mulch cover.
Visualize a small cherry tree that’s been in the ground a few years but never received any fertilization at the time of planting or thereafter. Chances are, unless that particular site happened already to be naturally very fertile, the tree is producing few cherries and maybe looks less than spunky. There can be about four different ground environments around the base and under the canopy; namely, bare ground, cultivated ground, grass (or other low-growing vegetation), or a mulch covering of bark, chips or leaves, etc. Which is best for the tree?
Surprisingly, grass is the worst; bare ground would be better, even if you had to hoe it up from time to time to keep grass and weeds out. Why is that? It’s because the grass competes with the tree roots for food. It also chokes off the supply of oxygen to the tree roots.
A person who drove that point home for me was Sir Albert Howard in his 1940 book An Agricultural Testament (see chapter IX). Sir Albert conducted some experiments (a.k.a. grow trials) in India with a variety of fruit trees. What he discovered was that the trees that had grass planted around them in the third year grew very poorly; whereas the trees that were clean cultivated underneath grew very well. However, what Howard did not do in this test was to mulch under some of the trees, let alone mulch and fertilize. Howard did find, however, that the older or larger the tree, the less effect grass had on it and, in the case of forest tree species, grass had no effect, apparently because deeper roots find more minerals and were less affected by low oxygen levels or got it from old root channels.
Besides the mulch itself, there are two main fertilizing components in our system. One of these is our BLOOM complete and mineralized organic fertilizers (according to the class of plant) and a liquid concoction we named Witches’ Brew, which gets poured on the bare ground and can also be applied as a foliar spray. Witches’ Brew is made from equal parts liquid fish, liquid seaweed, molasses and apple cider vinegar. You dilute it five tablespoons to a gallon of water and generously wet the ground.
An interesting question is what does each of these liquids contribute? Well, we know that liquid fish and liquid kelp are long-standing, premium natural fertilizers providing mainly the major elements (with fish) and a smorgasbord of trace minerals (with kelp). The molasses is an energy-rich food for soil microbes. The vinegar supplies certain kinds of microbes, also probably enzymes and vitamins, and may acidify the soil pH in a favorable way that helps to free-up various nutrients. But, beyond all those separate effects, there no doubt is a special synergy involved.
Another part of Howard’s research was to examine shallow and deep root growth patterns with the change of seasons in India. He did this by digging down as deep as 20 feet and washing (or hosing?) off the roots. What he found under the bare ground plants was that in the dry months, due to intense sunlight on the soil and high heat, the upper roots would go dormant or die-off. In the monsoon months the ground water would rise and drown the roots at the lower level or cause them to go dormant. Of course, when things are dormant there’s no growth going on. The return of the rains would stimulate roots in the upper soil to regrow, thus sending out new foliage on the trees and fruiting.
We can only wonder how those climatic extremes would have been moderated or what the effect would have been from supplying a mulch layer, and, more so, the effect of providing natural fertilizer that included nutrient minerals. We know that it does amazing things here compared to simply mulching or to doing nothing and to allowing grass to grow under shrubs and fruit trees.
One final thought about the Witches’ Brew, which you can purchase ready-made at BLO. It was developed for the Fertile Mulching System. If you use it as a more general liquid fertilizer, we can’t predict exactly what effect it will have or not have. Proceed at your own risk.
Once the liquid and granular fertilizers are put down and the mulch overlaid, then an ideal environment is created for microbes and earthworms to proliferate in a “climate-controlled” situation. The earthworms dine on decaying organic matter and on microbes, and they carry these down into the root zone and effectively stir the upper soil layer, distributing fertility, opening up the soil for aeration and water drainage, as well as creating an ideal nutrient pellet with their castings. Eventually, part of the overlying mulch gets decomposed, eaten and turned into a mineral-rich humus that further fosters feeding of the whole symbiotic network.
Meanwhile, the mulch (with optional cardboard layer) serves to suppress grass and weed growth beneath the tree and out as far as the applied mulch extends. Be sure to wet the ground and the cardboard when putting it down. Eventually, the cardboard also rots down and gets consumed by worms and microbes. Everyone is happy. Don’t say this story doesn’t have a happy ending.
© 2013 Gary L. Kline
All Rights Reserved