Practical Applications of the Indore Process [of Composting]
Sir Albert Howard, 1940
As is well known, the leaves of the sisal plant yields about 93 percent of waste material and about 7 percent of fibre, of which not more than 5 percent is ordinarily extracted. The wastes are removed from the decorticators by a stream of water, usually to some neighboring ravine or hollow in which they accumulate. Sometimes they are led into streams or rivers. The results are deplorable. Putrefaction takes place in the dumps and nuisance results, which can be detected for miles. The streams are contaminated and the fish are killed. On account of these primitive methods of waste disposal, the average sisal factory is a most depressing and disagreeable spot.
Seed shares at least one thing with sisal as a crop. Only a tiny fraction of the biomass from the growing season leaves the farm as product. The bulk of the carbon and nutrients are “waste,” in the common view, and they are in a difficult form (woody, bulky, and possibly disease ridden). There are also a lot of fine materials that come from the seed cleaning process, and these are thickly laced with weed seeds of every noxious kind (wild buckwheat, morning glory, grass, buttercup, bedstraw, wild geranium, mallow, pigweed), as well as the lightest fraction of every crop seed.
These leftovers cannot just be tilled in to be rid of them. The woodiness of kale stems approaches that of cord wood, so it does not go down easily. But worse, there is a terrible seedborne disease that afflicts the entire Brassica family, called Phoma or blackleg, and can persist in the woody tissues of Brassica seed stems and roots for up to 5 years. When these woody tissues are left on the soil surface, or when they return to the surface after a period of burial, they release infective ascospores into the wind from autumn through spring, spreading the disease widely. This is not a good mulch for the pathways.
As a matter of practice, many seed crops are cut at maturity, removed from the field, and windrowed on fabric to dry down before threshing. After threshing, the stems are not in a location where flailing and deep plowing are appropriate or possible. Indeed, they begin to pile up and soon there is a considerable heap of tough stuff that would plug any mower. And as we know, loading woody debris into the soil is a sure way to shut down productivity until all that stuff has rotted away, and nitrogen again becomes available for plant growth rather than decomposition.
We also eventually face the problem of disposing of seed which has become outdated. When the germ reaches some critical threshold it is time to refresh the supply with new crop, and sometimes many pounds (sometimes hundreds) must be dumped. Of course, the germ on these lots is commonly 75% or more, so wherever you dump it there will be volunteer crop sprouting for years, inviting common diseases and threatening to inflict cross pollination as volunteers.
The challenge then, and it is one that can’t be ignored for long, is how to handle these leftovers from seed growing, processing, and sale. Hot composting is really the only solution, and this reaffirms Sir Albert Howard’s observation that composting is not only about “the efficient manufacture of humus,” but is also about farm hygiene and the management of farm refuse. I seldom see reference to this aspect of composting, but it is one of the reasons that I have never been without a working pile on the farm.
There was a time when we were composting with soil building in mind. I have grown on some pretty depauperate soils in my career. Having a penchant for mountain agriculture (or really, just mountain living), I once farmed a glacial moraine near Puget Sound, where the earth was really more rock than soil. Nothing would grow there without a real layer of good compost, and I spent a lot of time composting fishery wastes and often whole spoiled fish with horse manure and any dry vegetation I could scrounge. That was some potent soil food, and it transformed the earth wherever it fell. This was during my salad days, well before seed debris was an issue to deal with.
Now our situation is different. We purchased real farming soil with 5.3-6% organic matter and a healthy mineral content, and our friends at Gathering Together Farm produce the finest compost one could ask for directly across the county road from us. I can purchase this as I need it for less than I can make it myself. So I don’t need to compost now as a matter of fertility management, but rather for the sake of farm health, and refuse sanitization and disposal. If we didn’t have the knowledge and experience to accomplish this properly, the results could be “deplorable,” as Howard puts it, leaving us in a “most depressing and disagreeable spot.”
I took it as a challenge to accomplish a hot composting system that would not require hauling in manure or other nitrogenous feedstocks to support the process. In part, this is just the kind of challenge to my self-reliance that I enjoy in life. Taking care of one’s own daily shit is harder than most folks realize, and having lived with a homemade composting toilet for 30 years, I can tell you it’s a matter of personal satisfaction. The difficult part of making sanitizing compost without imported manures is largely about timing of the availability of the different compost components.
In spring through summer in the Pacific Northwest we are flush with available greenery and the nitrogen it carries. I have acres of grass and white clover to mow from around the cultivated ground, the lawn, the orchard trees, slopes and ley areas where crops will eventually be laid out in windrows to dry down. By July the rain has stopped and this nitrogenous resource literally dries up. This is when seed harvest begins in earnest with Brassica, and the woody stems and tough seed husks begin to pile up quickly. In August, the spinach, then lettuce, then Beta crops arrive, with chard and beet stems like 6’ trees, followed by quinoa and everything else. By September the pile of dry woody materials is high and long. Then a different sort of waste looms, as the fruited crops of pepper, tomato, and squash need to be crushed to extract the seed. Once processed, these don’t wait around gracefully—they putrefy and become a nuisance of fruit flies and foul odors if they aren’t dealt with immediately. No, you can’t feed all this to pigs—in the first place there are never enough pigs nearby to eat 15 cubic yards of squash before it rots, in the second place it costs money to haul that heavy stuff anywhere. Thirdly, compost piles need to eat too. Seed cleaning begins in October, and chaff with its weeds and light crop seed fill tarps and bins to overflowing. The last week of October, about a quarter acre of 6’ fennel plants bury us in stems.
The pattern here is one of surplus nitrogen up until July, then a long period of dry brown materials, followed by sugary fruit bodies, cleaning fines, and umbel stalks. The problem is, those brown stems of late summer and autumn need the nitrogenous greens of spring and early summer to provide the nitrogen for decomposition. The delivery order of feedstocks for good compost is backwards.
To compensate for the natural order of things, I need to conserve the readily available nitrogen of the early season until the dry materials that need them arrive in enough abundance to absorb the nitrogen efficiently. I do this by making a spring/summer compost of mowed grass/clover/ley mixed with plenty of soil, weeds, overwintered debris, seed cleaning chaff, and some completely rotted wood chips. This makes a very hot pile and over-rich compost. The volume shrinks considerably for lack of carbonaceous bulk, and care must be taken to keep it moist. This pile will be used like sourdough starter for a much larger pile that will commence when the stems and seed shells of mustards become available in July. The starter pile is turned twice to aerate, evenly moisten, and uniformly decompose the materials. I make these piles like bread loaves, and keep them covered with permeable tarps that keep the surface warm and moist but allow for breathing.
As soon as the first Brassica crop is threshed, the stems are laid out alongside the starter pile. Keeping the stems parallel is always a good idea. It makes turning and handling the materials so much easier. At this time there are still mowings available to layer with the dry stems and seed shells. Thin layers of the starter pile material (it isn’t finished compost yet, more like a spoiled silage) top the mowings, and this layering continues until the pile is at least 4 feet tall. Materials are wetted with a hose as each layer is applied. This pile is about 6 feet wide by 12 feet long and uses 1/3 of the starter pile. When complete, the loaf is covered with a tarp to hold in moisture and heat. It will begin heating within 3 days, reaching 135F in short order. The next time mowings are available, more stems are added to extend the pile another 12 feet, and layers are made as before. Finally, a third section is piled this way making a pile about 36 feet long. The object is to create an actively cooking compost pile long enough to eventually digest all the seed refuse for the year.
Once active along its full length, this pile is ready to start absorbing every kind of refuse. August is a good time to empty the inventory of outdated seed, and I begin the sad task of dumping the work we didn’t get paid for, the breeding projects that were unfinished, 50 pound bins and packets with elaborate descriptive language. This is always a contemplative task, reminding me of grand ambitions and stupid ideas that are now being turned toward earth, reminding me that much of my time has been wasted, the price of experience. Such is life.
When composting seed, doubly so for noxious weed seed, it is essential to place it in the center of the pile. There is no room for sloppiness here. Actually, this entire process of layering materials requires as much care and thought of purpose as cooking a fine meal. For this reason, I am the only one who adds to this pile. When others try, I am seldom happy, like a chef with too many cooks in the kitchen. I want to stoke this beast, to get the temperature to 160F from end to end. Seeds and cleaning fines are great fuel for the purpose. The seeds are protein rich, and protein is where the nitrogen is stored in the living. The fines also have some nitrogen, coming from the seedheads where the mother plant directed all her dying resources. They have great surface area and little lignin, so are quickly consumed by the fungi and bacteria that are heating the pile, providing the energy needed to attack the tougher, intact stems. At 160F ammonia is being liberated from the rapid degeneration of proteins in the middle of the pile, but this precious gas is immediately absorbed by the woody tissues and decomposers eating them. Soil is added as a thin layer after feeding and watering, before re-covering with the tarp. Bacteria in this soil “casing” effectively scavenge ammonia that reaches the surface.
Because of the bulkiness of the stemmy layers, there is an overabundance of air in the pile. It is a good idea to tread the pile once a day at first to bring materials into intimate contact. This helps get the biological fire to spread, and it makes the new pile breathe, exhaling CO2 as you tread all over it, then inhaling oxygen when it rebounds. Bouncing on the pile is a bit like bellowing a fire.
More materials are added as the pile collapses, always keeping it at least 4 feet high. When the temperature falls to 140F, it’s time to turn. Though I mostly build the pile by hand, it is turned with the tractor bucket. From the uphill side, the bucket slides under the pile 18”, is slowly lifted to within 18” of the top, then moved forward to push the top over the far side of the pile, and this is repeated along the full length of the pile, essentially scalping off the outer layer and pushing it to the far side. This is repeated with another 18” scalping that buries the materials first removed. Essentially the pile is turned outside in and inside out, so that the new outer layer has all been pasteurized by heat, and the unsanitized material is now inside the beast, which quickly returns to 160F. That is the chef’s goal, a thorough and complete cooking of every morsel.
This pattern is repeated through seed cleaning season until every stem and fruit and bin of chaff has been included. The pile is slowly rolled down a gentle incline until the sanitizing is complete and materials are evenly mixed and actively decomposing. It remains covered against the rain until March, when it is turned once more. Once the temperature reaches 85F, it is ready for use.
Composting isn’t just about the end product. It produces benefits in a wholistic sense, and when properly managed functions as a sort of organic Dispose-All to a lot of potential problems. Compost can be a living, feeding being that spins straw and trouble into gold.
Originally published in the 2019 Wild Garden Seed Catalog.