One of the major shortcomings in my gardening approach I identified in the previous post is adequate soil preparation. Now, this isn’t to say that I have ever actively abused my soil by adding chemical fertilizers and pestcides. I never did either of those things. But it’s become painfully obvious through lack of productivity that I also have not provided enough additives to my soil to really get the natural, organic processes going that help to create and maintain fertile soil with minimal maintenance.
Last spring, I attempted to start up several forest garden patches at the same time while also addressing many other demands on my time which I won’t recount here. The end result was predictable, and much less successful than I had hoped. In one of the forest garden beds I built a low hugelkultur berm using pieces of rotting wood obtained from the floor of an adjacent woodlot — but I did not use sufficient topsoil cover in order for it to function as intended. For the rest of the garden beds, I tried to smother the underlying grass by spreading hay in a 6″ layer. While this suppressed the grass for a brief time, by the end of the season that grass had pretty much re-established itself in most areas. I attribute this to not taking the time to adequately kill off the grass before starting, not using a thick enough mulch layer (the hay settled to 3″ in many areas after multiple rain events) and not making a detailed planting schedule a core part of my garden design. In short, my desire to create my forest gardens now resulted in poor planning which created even more work in the end.
Now, I will say that there was one benefit from using all of this hay mulch — namely, in the areas where the grass came up through, it “shifted” the majority of its root structure from the underlying clayey soil into the rotting organic matter, making its removal this fall kind of like pulling up old carpet tacked into a subfloor. The grass is also providing plenty of fodder for composting.
More on that later — it’s time to return to the core part of this post, which is soil preparation. One of the local resources I have available to me in abundance is leaves. We have some trees around the edge of our property that drop their leaves every fall. The adjacent woodlot borders our road and dumps a thick layer of leaves along the shoulder of that road. Finally, residents of the nearby village gather up the leaves from their yards and put them in paper bags along the curb to be picked up and taken away for trash — I beat the DPW workers to the punch and pack them in the back of my Honda Fit to take home. One of my regular activities over the past two months has been mulching leaves with my walk-behind mower, and either dumping them directly on annual and forest garden beds as mulch or stockpiling them for next year.
I also moved my composting operation directly into my garden. I built a large bin out of some shipping pallets and chicken wire and placed it directly on one of the vegetable garden beds. Into this I piled the weeds pulled out of the neglected vegetable garden this fall (almost enough to fill the bin) and also deposit food scraps. This way the nutrients that leach down through will go directly into the garden bed — after this bin is filled and left to cure, it will be moved to a different part of the garden for the next load, providing nutrients for another area. Plus, all of my compost will be right at the point of use rather than in a different section of the yard, reducing the work required to place it.
I also buried food scraps and pulled weeds directly into my garden soil, but after beginning to read Dave Jacke’s Edible Forest Gardens Vol. 2 I decided not to do that again. Jacke mentions that this process causes the food waste to break down anaerobically rather than aerobically, fostering some of the less desirable bacteria and fungi in the process. I’ll have to see from production this year if this is, indeed, the case.
There is still one important and, thus far neglected task in soil preparation that I need to address. Compost and mulch will certainly help to foster the kind of self-sustaining vibrant soil ecosystem that is essential for successful permaculture gardening. But, without the right mineral nutrients present, it is not enough. Perhaps its the general seredipity of the universe at work, but lately I’ve been exposed to several different sources touting the use of rock dust as a soil additive to build and maintain the healthy soil necessary for growing healthy plants.
The first exposure that really hit me was a recording of organic farmer Dan Kittredge’s presentation as part of the Full Circle Series held at the NYC Horticultural Society. Kittredge is a second-generation organic farmer living in Massachusetts. He was compelled to develop growing methods for what he terms “nutrient-dense food” after many years of observing pervasive pest problems, consistently sickly plants, and mediocre yields on his parents’ organic farm. Today he owns his own very successful and diverse 15-acre organic farm in Western Massachusetts and heads up the Bionuntrient Food Association to spread the importance of growing and consuming healthy food as a means of ultimately bringing about meaningful social, economic and environmental change.
Kittredge’s solution to the problems experienced by his parents and many other organic farmers and gardeners is actually quite simple: rock dust. He says that many of the problems of pest infestation can be traced back to significant mineral deficiencies — especially among more trace minerals like manganese, boron and zinc – in the soil. His own experience with adding rock dust resulted in a quick revitalization of the soil to include decreased compaction and an upsurge in beneficial fungal and bacterial activity. The ability of his crops to take up these key minerals helps them to better resist disease from bacteria and fungus, as well as increase their protein content, thus making them much less palatable to insect pests. Kittredge openly states that he ONLY uses rock dust, diluted seawater and seaweed on his garden beds to achieve these outcomes — he does not compost, as he considers it to be too much work.
This subject was also broached around the same time in an episode of The Permaculture Podcast with Scott Mann. The episode posted on October 26, 2012 was “An Introduction to Nutrient Dense Farming with Mary Johnson.” Johnson touched on most of the same themes as Kittredge did, and she even cited him as one of the driving forces behind this work. While she delved a little more deeply into the biological science where Kittredge focused more on the practicality during his talk, the solution was essentially the same — revitalizing soils through the application of rock dust, diluted seawater and seaweed. Johnson referenced the traditional three sisters mounds as an example of the effectiveness of this approach, saying that the soil fertility in these mounds was enhanced every year by the addition of salmon carcasses harvested during each year’s salmon run. Since the salmon came from the oceans, they carried the mineral nutrients of the oceans upstream with them and then deposited it in the soils via their rotting bodies.
I also have to say that my mother — an organic gardener with over 40 years of experience but who still constantly experiments with new ideas – used rock dust on her garden this year and found that her yields were significantly increased as a result. So, with all of the evidence taken into account, I’m going to make use of it myself this year.
Most garden centers sell different forms of rock dust for different mineral deficiencies. However, I’m always on the lookout for resources that are either free or low-cost, and also that make use of another person’s “waste.” Toward that end, I’m going to reach out to rock quarries in the area and find out if I can take their rock dust for free. Dan Kittredge mentioned this approach in his Full Circle Series talk. In order to hopefully mitigate future difficulties it will be important to determine what rock type or types the dust was taken from.
I’m going to apply this rock dust on top of my thick layers of mulch and let the rain wash it down into the underlying mulch and soil. This method may take longer than tilling it into the soil, but I think it will be more effective over time. First, according to what Dave Jacke writes in Edible Forest Gardens Vol. 2, piling on mulch and other additives is a more effective method than tilling them in, because it mimics the way that nature does things and thus optimizes the systems already put in place for us. I also think that this will have the benefit of putting the minerals into direct contact with the bacteria and fungus that will be prevalent at the mulch-soil interface as the mulch rots down, allowing for more efficient transfer from the bacteria and fungus to the plant roots.
I know that the idea of continuously adding rock dust is not exactly a “self-sustaining system.” In order to try and encourage it to be so I’m relying on dynamic accumulators — especially comfrey — over the longer haul. By propagating comfrey throughout my herbaceous layer, it will capture the nutrients that leach through into the subsoil, as well as bring up the already existing minerals from the subsoil. When the growth is regularly cut and composted or mulched, those minerals will return to the topsoil where they can be taken up by other plants. By also introducing bio-intensive methods — namely the dedication of sizable portions of my gardens to growing fodder crops — those minerals can be brought up by plants and continuously recycled back into the topsoil as the plants are turned into mulch. My hope is that although the rock dust will be needed as a kickstart, it will only have to be done once and after that my gardens will be able to maintain their mineral content with just a little intervention at strategic points and times on my part.