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This week's Book of the Week feature is Building Soils Naturally, by Phil Nauta.
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From Chapter 8: Compost
Compost is our way of mimicking nature, yet speeding it up substantially. Whereas nature slowly decomposes animal manure, leaves and other organic matter all over the ground, we put a large amount of these things into a pile, in specific combinations and ratios, to make it happen quickly.
Compost is not natural. I love making and using compost, but we should remember that fact. Nature makes humus by covering the ground in plants that continually grow and die throughout the seasons and years. Masanobu Fukuoka points out in The One-Straw Revolution that we don’t need to compost if we maintain plant cover and mulch. This is true. The reason we compost is just to speed things up a little bit, particularly when we’re dealing with degraded soils. It works, but it doesn’t mean we should forget about mulching and maintaining plant cover.
We add compost to our soil to quickly increase the number and diversity of microbes and small animals, organic matter content, and nutrients in our soil, all of which are often low because of past gardening or other land use practices. A lot of resources refer to the organic matter and nutrients, but fail to focus on the microbes. The way compost breaks down is through the action of microbes, earthworms and insects. Their numbers multiply many times in the pile, and to me, they are the number one reason to compost. For most of us, getting that biology back into the soil is more important than using fertilizers.
How much compost should you make? As much as you’re willing to make. I’ve never heard a gardener complain of having too much compost. That being said, it’s better to concentrate your efforts on one properly managed pile than many, poorly managed piles. As you’ll see, you actually need very little compost to get big benefits. And you don’t have to get too scientific about it, but you do need to do a few things right. Poorly made compost can be plant-toxic putrefying organic matter.
I’m not going to list all of the materials you can use in your com- post. Obviously use good judgement, but pretty much anything that was once alive can go in there. The more variety in your raw materials, the more diverse the resulting compost. As you’ll see, I don’t use any genetically modified materials (GMOs), or a few others discussed in the upcoming chapter on supplementing nutrients.
The three most important ingredients in compost are plant parts such as leaves, weeds, grass clippings, and straw; manure; and food scraps. Useful supplementary materials include newspaper, cardboard, wood chips and sawdust. You can also throw in drier lint, tea bags, animal hair, vacuum cleaner dust and so on, but these will make up just a tiny portion of the pile.
There are dozens of materials out there. Some of them are available only in certain regions. Perhaps you have a beet processing plant or an apple cider producer near your house. These processes make wastes that can be composted, as does residue from cocoa beans, coffee, wineries and breweries. I taught a composting class for Gaia College where we used a nitrogen-rich material called okara, a soybean by-product from the manufacture of soymilk, tofu and tempeh.
You may not have enough stuff on your property to keep a good pile going. For this, get food scraps from your friends and neighbors and offer to take their leaves in the fall. Find a farm or orchard with some spoiled hay or fruit. While you’re out there, find a source of animal manure from a farm or stable. This isn’t absolutely necessary for the pile, but will definitely improve it. If you have many forests in your area, you’ll probably find someone selling or giving away sawdust or wood chips. In the city, find breweries, canneries or other food processors.
In the long term, a good goal for achieving a more sustainable garden is to use at least 50% of your garden beds to grow this biomass. Some of it can be turned into the soil, and some of it can be composted. Grasses and legumes are the best for this, and we’ll look at them in the cover crops chapter. To be as close to being sustainable as possible, we should really be composting our own human manure, too, and maybe even have some of our own animals that make manure for the garden.
Carbon and Nitrogen
We loosely categorize our materials as being carbon materials and nitrogen materials. Carbon materials tend to be yellow-brown and dry, so they’re often referred to as “browns.” They can have anywhere from a 30:1 carbon to nitrogen ratio to hundreds of times as much carbon as nitrogen. Nitrogen materials tend to be wet and often green, so they’re often called “greens.”
Despite the “greens” name, they still have more carbon than nitrogen, but the ratio is generally much lower — between 10:1 and 30:1. Just because something is actually brown in color doesn’t mean it’s necessarily a high-carbon material. Chicken manure, for example, is definitely a “green,” though if it actually looks green you should check what you’re feeding your chickens.
Carbon materials, roughly in order of increasing carbon content, include leaves, straw, hay, paper/cardboard, and wood/sawdust. Nitrogen materials, roughly in order of increasing nitrogen content, include manure, seaweed, grass clippings, alfalfa hay and food scraps, although manure varies depending on the animal and the freshness. In reality, all of these materials vary based on different factors. Kitchen scraps, for example, can range from being high in nitrogen to a moderate 25:1 carbon to nitrogen ratio. You can find many reference charts online with carbon to nitrogen ratios for common materials. It’s worth checking more than one, since they don’t always agree with each other’s estimates.
Most experts tell you not to compost cat and dog manure because they contain pathogens. I think we just need to know how to make a good pile that will kill most of the pathogens. Obviously we don’t want our pile to be 50% dog manure. It will more likely be 2% dog manure, and that’s just fine. It’s true that these manures contain pathogens. Cat manure contains a microbe that is hazardous to children and fetuses in the womb. It’s just as hazardous in the litter box and out on the lawn, so my opinion is that composting it is fine, as long as you’re building a proper compost.
Experts also say not to compost diseased plants, but I disagree. First of all, most pathogens will be killed in a well-made pile, and perhaps more importantly, their predators will be given a reason to flourish if their food source is around. We need some disease around in order to keep the predators that eat that disease around, so I put all diseased plants right into the pile.
About the only things I don’t compost are toxic materials such as colored paper and carpet, and noxious weeds such as quack grass and bindweed that may survive the composting process and be subsequently spread throughout the garden. But yes, I use oak leaves, pine needles, cooking oil, ashes, and even a small amount of meat in the middle of the pile.
If all of this sounds like a bit of work, it is. If you have more money than time, you can pay someone else to do it for you or buy compost, as long as it gets done. Using compost may be one of the most important things you can do for your garden.
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About the Author:
Phil Nauta grew up working for his parents in their garden center. He maintained the nursery stock in the yard and did some of the landscaping. Since then, he has played many roles in the organic gardening world. He started a gardening business called Only Organic, later taken over by his sister. He received his Permaculture Design Certificate and completed a certificate in Sustainable Building and Design from Yestermorrow Design Build School. He became a Certified Organic Land Care Professional through SOUL, The Society For Organic Urban Land Care. He later served as SOUL Treasurer for three years and continues to maintain their website. He started The Organic Gardener’s Pantry to sell high quality organic fertilizers. He has taught courses for Gaia College and helped put together their cutting edge online learning environment.
Titles of Similar Interest:
The Biological Farmer, Second Edition, by Gary F. Zimmer & Leilani Zimmer-Durand
Hands-On Agronomy, by Neal Kinsey & Charles Walters
Humusphere, by Herwig Pommeresche