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Contents:
Compost
Organic Soil Amendments and Mulches
Soil Nutrients
Composting is a form of digestion; it is a way to reuse/recycle organic materials, turning them into humus, the organic portion of soil. Decomposition of organic material will take place under all but the most extreme conditions, however, the ongoing existence of a composting process, regularly producing a valuable fertilizer and soil amendment, depends on the creation of a situation favorable to the mini- and micro-organisms whose biological activity cause differentiated plant material to break down into a substance which nourishes soil and another generation of plants.
The essentials for composting, the things that you don't always have enough of are: volume, water, nitrogen, and oxygen.
Basics of Composting
In order to make finished (usable) compost within the time frame of the growing
season, all the above essentials must be attended to at all times. In other
words, the saying “compost happens” is not entirely true. Here
are some guidelines that will make your compost project more successful.
Materials in compost – Some of the material should be water absorbent. Dried weeds and leaves, hay, saw dust and wood shavings. Ingredients should be added in amounts that approximately balance the following:
The nutrient content of your finished compost is related to the variety of materials put in. Seaweed, if available, can be added for minerals.
Methods of creation – The pile can be either built up gradually (over days, weeks, or months) or, if materials are on hand, it can be created in one day. In either case, alternate different types of material and water as you go.
Turning compost – This is the famed activity that determines if you are a “compost happens” person or an active composter. The more you turn your compost, the faster it works. Turning means completely flipping the pile upside-down. You want to, more or less, switch the top and bottom, the inside and outside. Do this with a sturdy spading fork. A shovel meets too much resistance. Turning compost oxygenates the pile and redistributes moisture. Try to break up clumps. For backyard composting units, turning the top 12-18 inches is sufficient.
Using compost – Finished compost looks, feels and smells like good soil. It should be protected from rain or nutrients will leach out. Any amount of compost can be added to your garden in the spring and before winter, however it is usually at a premium, so one to two inches all around, or whatever you have on hand will help. It can be dug into the topsoil or spread on the surface. Compost is also used during transplanting, as a side dressing, seasonally to boost production of flowers, fruit, etc. You can also make compost tea by mixing one part finished compost with l0-15 parts water. Soluble nutrients get to the roots quickly. Compost may be sifted if you desire. A plastic milk crate makes a fine sifter. Undecomposed material goes back in the pile for further composting.
Special compost piles
Leaves - Dried fall leaves are high in carbon and low in nitrogen.
Also, they don't hold water well unless they are shredded. Thus, most people
don't expect to get usable compost from their leaves for a year or more. You
can speed up leaf composting with the following three techniques.
Seeded compost - Late in the summer when weeds have mature seeds, you should be cautious about adding them to your pile. Some seeds will be rendered unviable by heat and constant moisture. Some will germinate and die. If you are adding mature seeds, put them in the center and provide plenty of moisture. You can make a separate compost heap of mature weeds as follows. Pull up weeds, keeping tops together and roots together. Bend in half to put roots and soil in contact with seeds. Make a circle with seeds and roots in the center and the bent stems at the outside. For each laver, cover seeds and roots with soil and water. After the seeds have rotted, layer the material into another compost pile.
Vermicomposting – When low volume and low temperatures are a factor, you can use earthworms to convert food scraps into an excellent fertilizer. Red wigglers (Eisenia foetida) are the worms that eat food directly rather than soil. If proper moisture and oxygen are provided, a colony of worms can compost for you all winter and leave you a box full of worm "castings." Start with a pound of red wigglers in a box (about 2 feet by 2 feet by one foot high) nearly filled with wet shredded newspaper, brown bags or corrugated cardboard mixed with a few cups of soil. Bury ½ to 2 pounds of food scraps and rotate where you place food. In about 5 months the worms will eat all the paper and food. At that point, you can separate the worms from the castings by exposing the vermicompost to light, which causes the worms to dig down. Thus they get concentrated and you can retrieve them for your next worm box. (Click here for more information on vermicomposting.)
Location – A compost pile should be convenient to its source materials and/or the place where the finished compost will be used. In the summer you will appreciate being under a tree for shade and rain protection while working the pile.
Covering layer – To keep moisture and heat in the pile, cover it with plastic or organic materials such as leaves, weeds, hay. However, since the top layer will be dry and probably carbon rather than nitrogen materials, it is best to remove it when adding new stuff. Eventually this mulch can be incorporated into the pile.
When to stop – At some point you should declare a compost pile closed and start a new one. You may turn it, but don't add any more new material with the possible exception of quickly decomposing nitrogen sources such as grass clippings or coffee grounds. If you keep adding stuff you'll never have clean finished compost to use.
For a great article from Rodale's Chemical-Free Yard & Garden with lots of general information on composting, click here. For specific information on the biology of composting from the Massachusetts Department of Environmental Protection's Division of Solid Waste Management, click here.
Organic Soil Amendments and Mulches
You can choose from a wide range of materials to layer on or dig into your soils. Factors to consider in selecting soil amendments and mulches are the availability, cost, ease of handling, and pH range of the materials.
Compost: Finished compost is the best soil amendment. You can make it yourself or buy it commercially. Finished compost is well on its way to becoming stable humus. When mixed into the soil, it resists compaction and drains quickly, yet still retains an enormous amount of water. Compost will retain ten times its weight in water. It also serves as fodder for the “micro-herd,” the soil microorganisms that break organic material down into nutrients in a form readily taken up by plant roots. Compost will vary a great deal in NPK content because of the variety of materials that can be used to make it. However, homemade compost is likely to have at least 1/2 pound each of nitrogen, phosphorus, and potassium in 100 pounds of finished product. See “Compost: Nature's Black Magic” for more information on this important soil amendment.
Shredded leaves: If you don't have enough compost to feed all the soil in your yard and garden, chopped leaves are a good second choice. Leaves are cheap, readily available, and easy to use.
Be sure to chop or shred leaves before using them as a mulch or soil amendment. Whole leaves blow away easily when dry, and after wetting can form a crusted mat that keeps almost all moisture from seeping through to the soil underneath. If you incorporate whole leaves into the soil, they will take much longer to decay than chopped leaves. If you don't own a shredder, you can shred your leaves with a lawn mower. Run the mower repeatedly over a pile of leaves, crisscrossing the leaves until only small pieces remain.
Most leaves are acidic, but will not add enough acidity to significantly affect soil pH. Pine needles are even more acidic, and may reduce soil pH. Chopped leaves are also low in nitrogen, but you can add from 100 to 200 pounds of leaves to 1,000 square feet of garden without significantly tying up soil nitrogen.
Grass clippings: Grass clippings are frequently recommended as a good organic mulch for flower and vegetable beds. While technically true, why remove grass clippings from the lawn when they are the very best organic amendment for lawns? Leaving grass clippings on the lawn not only builds the humus content of the lawn soil, but also adds nitrogen, reducing lawn fertilizing needs by as much as 30 percent. If you mow frequently, the clippings will fall down among the grass plants and never show. The only times you should rake off grass clippings are if your lawn has a thatch accumulation problem, or if you have mown very tall grass. Dense clumps of long clippings could shade out portions of the turf.
If you do rake old lawn clippings, use them as mulch or add them to the compost pile. The nitrogen content of grass clippings is high, and almost immediately available. However, they will not last more than a few weeks as a mulch. Grass-clipping mulches work well around nitrogen-loving vegetable crops like spinach and lettuce. Because you can adjust the depth of this mulch so easily, you can spread a thin layer around plants while they are still quite young. Be sure to leave a little open space around each plant, because fresh grass clippings can give off enough heat as they rapidly decompose to burn vegetable and flower transplants. It's your choice whether to use grass clippings to help fertilize your lawn or to mulch your vegetables. If you're selective in your use of lawn clippings, you might be able to pull off both. Just remove a portion of your lawn clippings for mulching jobs, changing the area from which you take them at each mowing.
Aged manure: Aged manure is a wonderful soil amendment. It adds material well on its way to becoming humus and is a significant source of nutrients. Unfortunately, animal manure is not readily available to most home gardeners. If you can get manure, add it to soil only after it has aged for at least six months. Aged manure varies in its NPK ratio, depending on the animal source and on how much it has been leached by rains during aging. Some soil testing laboratories will analyze aged manure nutrient content. Testing will help you decide application rates and the need for other inputs, such as rock phosphate or greensand.
Hay and straw: Hay and straw are generally inexpensive sources of organic material. They are relatively low in nutrients, but will give soil a big boost in humus. They are available directly from farms or from any source that serves livestock owners, so check the telephone directory yellow page under “Feed Dealers.”
Hay usually carries seeds of weed plants that mature easier than the grasses in the field where it was cut. Consequently, many chemical-free growers try not to use hay. A hay mulch also is a favorite habitat for rodents and slugs. If you've been having mouse or slug problems, think twice about using hay, or refine your techniques to minimize damage. For example, hay pushed close to a fruit tree seedling gives mice a perfect opportunity to nibble on the succulent bark through the winter when other food isn't available. Leave at least 2 feet of bare soil surface between a hay mulch and the tree stem. And while mulches do encourage ground beetles that prey on slugs, that benefit might not outweigh the damage in some situations. For example, if you mulch with hay directly under your tomato plants, either reconcile yourself to losses from slug damage or be certain to stake or support the plant so well that fruits are suspended well above the mulch.
Straw generally carries few weed seeds, since most of these seeds were removed in the same process that separated the grain seed from the straw. Straw mulch also holds up better over a growing season than a hay mulch.
Peat moss: Peat mosses, including sphagnum peat moss, are remains of aquatic plants that have been deposited in locations not favorable for their quick breakdown due to high water tables and/or extended periods of cold temperatures. The pH of peat moss is acidic, ranging from 3.0 to 4.5; the nitrogen content is low, and the water absorbing capacity is very high. Peat moss is a useful soil amendment around acid loving plants such as rhododendrons, azaleas, hemlock, pine, and spruce. Peat humus or sedge peat, also known as reed peat or humus, can be used in the same manner as peat moss. Sedge peat or peat humus is dark brown to black and is relatively high in nitrogen (2.0 to 3.5 percent). It has a lower water-absorbing capacity than peat moss, and it will break down more quickly in the soil.
Sawdust: Use sawdust as a mulch or soil amendment only after it has aged. Some types of sawdust contain natural chemicals that can act as herbicides. If you put fresh sawdust on or in your soil, it may temporarily sterilize the soil. Fresh sawdust also needs nitrogen to break down, so it robs nitrogen from your plants, unless extra nitrogen is mixed in with it. Aged sawdust is very low in nitrogen. If you apply it to nitrogen demanding crops such as vegetables or annual flowers, mix it with some manure, bloodmeal, or compost to supply nitrogen. If the compost has aged for 2 years or more and has turned black, you do not need to add nitrogen when you apply it. This aged material has little nutrient value, but will increase the organic matter content of the soil.
Wood chips: Bark and wood chips are often used as mulches. They work well to keep down weeds in established ornamental beds or plantings of perennial herbs. Like sawdust, these materials contain much more carbon than nitrogen. As soil microorganisms slowly digest these mulches, their populations swell. However, the microbes also need nitrogen to build their cells, so they may tie up soil nitrogen that plants need for optimum growth. Avoid this problem by spreading 1 inch of compost or well-aged manure before laying down wood chips or bark. Observe the plants carefully in succeeding seasons; you may need to water with a nitrogen-rich solution of manure tea or fish emulsion if the plants show signs of deficiency. Don't dig in bark or wood chips as a soil amendment. The materials are too large to attacked by the “micro herd.”
Locally available materials: You may be able to find natural materials or manufacturing by-products in your area that serve as valuable soil amendments and mulches. Gardeners who live near the ocean may be able to collect seaweed. Rinse it well before adding it to your garden or compost pile. Other possible materials include apple pomace from a cider mill, soybean wastes from tofu making, cheese whey, nut shells, mushroom soil, and ground corn cobs. If you're getting an agricultural by-product, be sure to ask whether the source crops were treated with pesticides. The by-products could contain residues of these chemicals.
Excerpted with permission from Rodale's Chemical-Free Yard & Garden. To order, call 1-800-848-4735 or write to 33 E. Minor St., Emmaus. PA 18098.
EarthWorks' Notes: Peat moss is generally not sustainable harvested, and is not recommended as it destroys peat wetlands.
Examples - Iron (Fe) is optimally available at pH's lower than 6.5. Above 6.5, iron becomes increasingly less available to plants. Zinc (Z) is optimally available between pH 5.0 and 7.2.
Chart excerpted from Stella Otto's The Backyard Berry Book (p. 53), Otographics, 8028 Maple City Road, Maple City, MI 49664.
Another chart found in The Backyard Berry Book, “Interactions of Soil Nutrients,” might be helpful if you want to see how levels of particular nutrients can affect other nutrient levels.
An assessment of your soil by a soil testing laboratory, as well as your personal observations and the specific requirements of the crops you are growing can provide you with information as to which nutirents are predominant and deficient in your soil. A helpful chart in selecting organic fertilizers to amend your soil can be found in Rodale's Chemical-Free Yard and Garden. Also, Robert Kourik's Designing and Maintaining your Edible Landscape Naturally contains two informative articles, one explaining how to grow your own cover crops and green manures (linked here), and another dealing with dynamic accumulators – plants that help to accumulate soil nutrients.
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