Soil loss in the tropics is fast! Soil losses of up to 500 tons per hectare*, per year can occur as a result of deforestation and bad land management practices. Even in the home garden soils are often sandy and leached of most of its organic matter. Fortunately, decomposition in the tropics is also fast. The breakdown of organic matter is rapid; and with the rampant growth during the rainy season, facilitating soil creation can be achieved relatively quickly.
Here are a few of my preferred techniques for building soil quickly that may seem a little unusual to the conventional farmer or gardener, but are nonetheless very effective.
What i like to call “bulk mulching”, sometimes referred to as “rough mulching”, is the practice of using large, chunky, relatively unprocessed pieces of organic matter like tree limbs, stumps, and banana stalks laid out on the ground to break down in situ. This technique is meant to closely resemble what happens in a forest.
People often ask me whether this is the same thing as using chipped wood mulch. My experience is that using whole pieces of wood material achieves a much different result. In fact, when I get wood chip mulch from local arborists, I often ask for the tree limbs and stumps that were too large to put through the power chipper. Wood chips make great mulch, but they break down quickly. Whole pieces of wood, particularly hard wood, break down slowly, allowing time for more long term, slow feeding, beneficial fungi to work at them. As these larger pieces of material breakdown, they become like little condominiums for all kinds of soil creatures from microorganisms and fungi to wood lice and millipedes.
Another benefit is that when large pieces of wood root, they become very spongy and waterlogged. I like to think of it as a slow release irrigation system. Once completely broken down, they make a very fine humus, resembling espresso coffee grounds. This humus layer helps keep the top soil damp, even in dry periods. Additionally, humic acid leaching into the soil helps dissolve rock and minerals, making them available to plants. The key to using this kind of material is that it makes good contact with the soil, allowing the fungi to quickly start the decomposition cycle. I often line my garden beds with woody material and shredded banana stalks, completely sheeting the ground. Depending on the diameter of the material, I like to cut pieces about 12 -18 inches in length. Next, I come back and put in pockets of compost and insert seedlings and seeds.
Ernst Götsch’s Syntropic agroforestry system is a well known example of this technique. After hard pruning trees and bananas, he neatly arranges the material shoulder to shoulder, lining his garden path ways and beds. Geoff Lawton has adopted a similar technique, lining the pathway edges of his food forest with bulky material laid-out on contour. The latter technique has the added advantage of acting as a snag for organic material and slows overland water flow. Large pieces could even be inoculated with gourmet mushrooms.
Instant garden beds:
This technique is simple, straightforward and quick. First, organic material like kitchen food scraps are laid out on the ground; no need to worry about weeds or grass. Next, a layer of manure is laid down. This is followed by a thick light-proof layer like cardboard or paper. This light-proof layer will help block sun to weed seeds, smother the grass and trap moisture, especially if the material is soaked in water or worm tea first. The layers in between and below the cardboard become a favorite place for earthworms to occupy.
Next, the paper is topped with a thick layer of mulch 12” -18” ( 30-45 cm). Usually this is pasture slashing, straw or hay. I like to use manured duck bedding from our duck pen.
To plant: a small “nest“ is hollowed out in the mulch and a few holes are punched in the paper layer. A large, double handful of compost is then placed in the hollow in the mulch. Lastly, a plant seedling or seeds are placed in the nest.
The nice thing about this method is that this sort of “lasagna layering” can be repeated over and over until you’ve built up a raised bed of deep, fertile soil. Just continue adding material on top.
This is by far my favorite. It consist of a pit dug in the ground with the spoils piled around the rim to form a donut like mound. Around this are planted species of plants that like moisture and are heavy feeders. Banana, papaya, coconut, squash, sweet potato, taro, etc. Then the pit is filled with rough mulch and manure. The pit stays moist for months, especially if you line the bottom with logs, and the plants feed centrally saving space and stacking functions. And since there is little light penetration, little to no weeds grow. It’s rather satisfying to throw big chunky awkward yard debris in the pit. Items that would have taken hours to chop up or haul off. It also keeps the biomass out of landfills. Palm fronds, tree branches, weeds, card board, urine ( in moderation ), coconuts etc. are all suitable materials. I’ve even heard of people throwing in tin cans for iron. Bananas grown in this manner grow like weeds and outpreform all our other clumps, especially in the dry season. These gardens are more intended for the tropics but could be adapted for other climates. In dryer climates, grey water can be directed to these pits.
The edges can be dressed up a bit with ground cover like sweet potato for a tidier look. Eventually, you are left with a deep pit of extremely fertile soil that can be harvested or planted with a long term fruit or rainforest tree.
The great thing about these three methods are that they are straightforward, use readily available materials and don’t require any machinery or special technical knowledge. By mimicking nature, we can build soil quickly and start the process to recovering one of our most precious resources.
Geoff Lawton talks mulch and chop & drop in a food forest: https://youtu.be/mHoW92qT03s
Geoff’s instant garden explained: https://youtu.be/S5wgHQtxgJw
Ernst Götsch Syntropic technique: https://youtu.be/gSPNRu4ZPvE
See the author’s technique in action here
* “Permiculture A Designers’ Manual” by Bill Mollison