I have lots of kitchen scraps (eggshells, coffee grounds, fruit and vegetable peelings) but cannot figure out how to develop compost out of it. Everything I’ve read says to add green and brown such as dried leaves and green grass to it. I need to figure out some sort of ratio. But how?
Books have been written on the topic of making compost; my current favorite is Compost Gardening by Barbara Pleasant and Deborah L. Martin. It represents a wealth of wisdom and practical experience on a topic that, when it comes down to it, is really quite simple. The decomposition of organic matter into compost is going to happen whether you’re measuring and manipulating the materials in a pile or not. “Compost happens,” as the tongue-in-cheek bumper sticker says.
The ratio you’re referring to is the balance of carbon-rich materials (or “brown” ingredients, such as straw, shredded paper, sawdust, and dry leaves) to nitrogen-rich materials (the “greens,” including your kitchen scraps, manure, and fresh grass clippings or weeds). In theory, a proper balance of these ingredients makes for a fast and efficient compost pile. In practice, however, most gardeners add whatever organic debris we have on hand to our compost piles without giving much thought to the carbon-nitrogen ratio. We end up with compost, too, even if it takes longer than it would with a perfectly managed pile.
You can layer your kitchen scraps with dry leaves or other “browns” in a pile or bin. Or you can try pit composting, a technique that involves digging holes or trenches in the garden (often between rows of vegetables or in fallow areas of the garden), depositing your kitchen scraps in the ground, and immediately covering them with soil. The scraps break down quickly—and you don’t have to worry about getting the ratio right.
For more information about how to make and use compost, you’ll find a great collection of articles and videos on this website. —Doug Hall
Please define organic where using superphosphate is concerned. Also when using 10-10-10. Thank you.
Superphosphate is a synthetic chemical fertilizer that is not approved for use in organic agriculture. It is manufactured by treating mined phosphate rock with sulfuric acid. It’s toxic to the microbial life of your soil. Because it’s water soluble, it can also contribute to phosphorus pollution of waterways.
If your garden soil lacks phosphorus, it’s better to apply it in the form of bone meal, rock phosphate, composted poultry manure, or compost made from yard waste and kitchen scraps. These organic materials release phosphorus to the soil slowly as they are broken down by soil bacteria. Fish emulsion and liquid seaweed fertilizers offer a quick phosphorus boost.
The ratio 10-10-10 describes the quantities of nutrients within a fertilizer but doesn’t reveal whether or not it’s organic. That said, the vast majority of fertilizers with a 10-10-10 analysis are synthetic. The three numbers represent the percentages of available nitrogen, phosphorus, and potassium in the fertilizer.
Gardeners who are in the habit of regularly feeding their soil with rich compost often find that they have no need for additional fertilizers. If necessary, you can supplement compost with complete organic fertilizers that blend natural sources of nitrogen, phosphorus, and potassium, as well as micronutrients such as iron and calcium. You’ll know which products at the garden center are organic by their “OMRI Listed” label. —Doug Hall
My order of 50 bareroot strawberry plants will arrive at the end of April. The supplier recommends mixing 10-10-10 chemical fertilizer into the soil. Can you suggest an organic alternative? I have some horse manure, but it doesn’t appear to be fully rotted to use at this time.
Strawberries grow best where the soil is fertile, well-drained, and amply enriched with organic matter. If you have been using compost, organic mulches, and cover crops in your garden for several years, you may need to do nothing further before planting the strawberries. A soil test will give you an accurate reading of how fertile your soil is.
If your soil falls short of the ideal, I recommend you dig in some organic amendments before you plant. Composted horse or steer manure is excellent for this purpose; it’s sufficiently composted when it looks and smells like soil. Yard-waste compost is another good source of nutrients and organic matter. Sphagnum peat moss as a soil amendment adds organic matter but little in the way of nutrients. Ideally, you should prepare the soil a few weeks before planting the strawberries.
Water thoroughly after planting, then give each plant one cup of a half-strength fish emulsion solution or compost tea to jump-start growth. Follow up 3 weeks later with another application if growth is slow.
Let your supply of fresh horse manure decompose longer before using it. You can layer it with leaves, kitchen scraps, and other garden debris to make compost, if you wish, or simply let it age in a pile. Next spring, use it to top-dress the strawberry bed when the plants begin to bloom. —Doug Hall
I’m not sure what to do with all my excess wood ash from the fireplace. I need to lower my soil pH, so I can’t add the ash to the garden or compost.
The ash from a wood-burning fireplace contains nutrients that plants need, including potassium, calcium, and trace amounts of zinc, magnesium, and phosphorus. But those nutrients come with a warning: Wood ash is strongly alkaline. If added to soil, it will raise the pH, or the measure of a soil’s acidity or alkalinity. Where the soil is too acidic (pH too low) and a higher pH would be beneficial, wood ash can be applied to lawns or gardens in place of agricultural lime to raise the pH. But if you are dealing with a neutral or alkaline (high pH) soil, adding wood ash would be a mistake.
The same goes for adding wood ash to a compost pile. Consider including wood ash as a compost ingredient only if the pile contains significant quantities of acidic materials, such as shredded oak leaves or pine needles. Even then, apply the ash with restraint, because too much can result in a loss of nitrogen from the compost. At a higher pH, the nitrogen present in the compost pile will escape to the air as ammonium hydroxide; if you smell ammonia near your compost pile, it’s losing nitrogen.
If you decide you shouldn’t use wood ash in your garden or compost, and you can’t find a farmer or gardener who can use it, I suggest you send the ash to a landfill with the rest of your household waste. —Doug Hall
Last week you recommended burying kitchen scraps to let them compost directly in the soil. But I have seen raccoons in my neighborhood. What if they dig up my garden to get at the compost?
Whether you compost aboveground or below, animals may be attracted by the smell of the composting scraps and dig into the pile in search of something edible. Fences will keep out neighborhood dogs but they aren’t much help when it comes to excluding other digging or burrowing animals, such as rats, field mice, and raccoons.
Some manufactured composting bins and tumblers are designed to be critter-proof, with solid sides and tight-fitting lids. Homemade compost bins can be lined with wire mesh or hardware cloth. When pit composting, bury the compostables under several inches of soil. This makes it less likely that marauding animals will smell food and dig.
Don’t add meat or dairy products to your compost pile. If the problem with unwanted wildlife persists, eliminate kitchen scraps entirely and compost only yard wastes—things that won’t interest raccoons, like leaves, grass clippings, shrub prunings, and weeds. —Doug Hall
I want to recycle my kitchen scraps in the garden but I have no room in my back yard for a compost pile. What’s a good way to compost that doesn’t take much space?
Dig a hole, dump in your compostable kitchen waste, and cover it with soil. Most of the scraps break down in a month or less (things like melon rinds and eggshells might take longer), and during that time you don’t have to worry about the temperature or moisture level of the decomposing organic waste, nor do you need to stir or turn the materials. Soil microbes and earthworms do all the work for you.
This technique, called pit composting, is especially good in vegetable gardens, because you can bury your scraps between rows or wherever a crop has just been harvested. The nutrients from the decomposing organic materials are released slowly to the soil and are available for crops that follow. As with aboveground compost piles, you should avoid adding meat or dairy wastes, which can attract animals. Pit composting is difficult for large amounts of yard debris, but it’s a good way to deal with the day’s coffee grounds, potato peelings, apple cores, and other food wastes. —Doug Hall
The other day, an Organic Gardening reader emailed us a question about whether or not he should add shredded newspapers to his compost pile. (My opinion: Shredded newspaper is OK in moderation, especially in piles that are blessed with too much nitrogen and need some extra carbon-rich materials to balance it out. In my garden at home I’m more likely to utilize newspapers in an unshredded layer under the mulch, where they have a compounding influence on the mulch’s beneficial effects.)
The reader’s question inspired me to start a list of items that shouldn’t be added to a compost pile. Weeds that have gone to seed; meat scraps from the kitchen; used cat litter: Some things are obviously unwelcome as compost ingredients.
Others require some research. Wood ash, for example, is often considered a safe compost ingredient—in small quantities. But it is highly alkaline and raises the pH of the decomposing pile, allowing nitrogen to be released into the air as ammonia gas. Not just smelly, but a waste of an essential plant nutrient.
In the end, I came up with 10 items that are best kept out of the compost bin. Look for the list in the Skills & Abilities section of the June/July 2011 issue of Organic Gardening. —Doug Hall