Tuesday, August 5, 2008


Vermicompost (also called worm compost, vermicast, worm castings, worm humus or worm manure) is the end-product of the breakdown of organic matter by some species of earthworm. Vermicompost is a nutrient-rich, organic fertilizer and soil conditioner. The process of producing vermicompost is called vermicomposting . The earthworm species (or composting worms) most often used are Red Wigglers (Eisenia foetida) or Red Earthworms (Lumbricus rubellus). These species are commonly found in organic rich soils throughout Europe and north America and especially prefer the special conditions in rotting vegetation, compost and manure piles. Composting worms are available from nursery mail-order suppliers or angling (fishing) shops where they are sold as bait. Small-scale vermicomposting is well-suited to turn kitchen waste into high-quality soil, where space is limited. Together with bacteria, earthworms are the major catalyst for decomposition in a healthy vermicomposting system, although other soil species also play a contributing role: these include insects, other worms and molds.
Starting off When beginning a vermicomposting bin, moist bedding is put into the bin and the worms are added. In hot climates, the bin is placed away from direct sunlight. Appropriate waste can be added daily or weekly. At first, the worms are fed at most half their body weight per day. After they have established themselves, they can be fed up to their entire body weight. It is best not to add new food on top of old food until the old food has been processed by the worms. However, new food can be added in a different location in the bin. Bedding Bedding is the living medium and also a food source for the worms. It is material high in carbon and made to mimic decaying dried leaves on the forest floor, the worms' natural habitat. The bedding should be moist (often similar to the consistency of a wrung-out sponge) and loose to enable the worms to breathe and to facilitate aerobic decomposition of the food that is buried in it. A wide variety of bedding materials can be used, including shredded newspaper, sawdust, hay, cardboard, coir, burlap coffee sacks, peat moss, pre-composted (aged) manure, and dried leaves. Cat litter, and pet and human waste should not be used. Most vermicomposters avoid using glossy paper from newspapers and magazines, junk mail, and shredded paper from offices, because they may contain toxins which may disrupt the system. Also, coated cardboard that contains wax or plastic, such as milk boxes, cannot be used. Newspaper and phone books printed on regular, non-glossy paper with non-toxic soy ink are safe for use, and decompose relatively quickly. Some bedding is easier to use and add food scraps to than others. Temperature Worms used in composting systems prefer temperatures of 55 to 70 degrees Fahrenheit (12-21 degrees Celsius). The temperature of the bedding should not drop below freezing or above 89.6 °F (32 °C). This temperature range means that indoor vermicomposting is suitable for homes in all but tropical climates. Food Worms and other composting organisms have a preferred ratio of carbon to nitrogen (C:N), approximately 30:1. As some waste is richer in carbon and others in nitrogen, waste must be mixed to approximate the ideal ratio. "Brown matter", or wood products such as shredded papers, is rich in carbon. "Green matter", such as food scraps, has more nitrogen, which is related to the amount of protein in the waste. If the waste is mostly vegetable and fruit scraps, and does not regularly include animal products or high-protein vegetable foods like beans, the resulting vermicompost and waste liquid will be low in nitrogen. Suitable Kitchen waste suitable for worms includes coffee grounds and filters, tea bags and plate scrapings, as well as rotting fruit (including citrus fruit but NOT citrus peel), vegetable peels, leftovers, moldy bread, etc. These materials can be raw or cooked. They do not have to be ground up, as the micro-organisms in the bin will gradually soften them. However, if a large quantity of dry food (e.g., moldy bread) is added and covered with bedding, pour a little purified water over the bedding to moisten the mixture. If too much kitchen waste is added, the bin mixture putrifies before the worms can process it and becomes harmful to the worms. High-protein foods like beans are particularly susceptible. Check the bin at least once a week, give the materials a stir to oxygenate, and add bedding if the bin appears too moist. Soft garden wastes such as carrot tops and tomato leaves are suitable foods. An occasional sprinkling of garden soil in the bin gives the worms the grit they need to digest food. It's not harmful to throw in an entire plant, but the worms will not process the woody parts or large roots and these will have to be hand-removed later from the finished vermicompost. Compostable plates, cups, etc. are also suitable, but in small bins they should be torn first into smaller pieces so as not to block oxygen flow. Unsuitable High-water-content materials like watermelon rinds provide very little food for the worms while disrupting the moisture level of the system. They should be added sparingly. Grass clippings and other products sprayed with pesticides should be avoided. Some banana peels are heavily sprayed, and can kill everything if added to a small bin. Although worms can digest proteins and fats in meat scraps, these materials can attract scavengers. Too much oil or fat can hinder the breathing of the worms, as they breathe through their skin. Worms cannot break down bone and are said to dislike highly spiced foods such as onions[citation needed], garlic, and salt. If possible, sticky food labels, rubber bands, tea bag staples, and other inedibles should be removed before placing the food in the worm bin, as these items will not decompose. Fruit pits need not be removed from decaying fruit before adding, as the worms will eat all the soft matter. Compostable cutlery takes too long to degrade in vermicompost. Bin Maintenance Worms and other composting microorganisms require oxygen, so the bin must "breathe". This can be accomplished by regularly removing the composted material, adding holes to the bin, or using a continuous-flow bin. If insufficient oxygen is available, the decay becomes anaerobic, like that in swamps and bogs, producing a strong odor and creating a toxic environment for the worms. The moisture level and oxygen flow in a home worm bin should be checked at least once a week. Over the long term, care should be taken to maintain optimum moisture levels. In a non-continuous-flow vermicomposting bin, excess liquid can be drained via a tap and used as plant food. A continuous flow bin does not retain excess liquid and, depending on the foods used, may require sprinklings of water to keep the bedding moist. The pH should be slightly alkaline. Alkalinity can be increased by occasionally adding a handful of calcium carbonate, sold as "garden lime." Do not confuse calcium carbonate with regular lime (Calcium oxide), which is far too alkaline and will kill worms. Adding many citrus peels can hinder the worms, but probably due not to acidity but to d-limonene, a fragrant chemical present in the rind of citrus fruits. Coffee grounds have sometimes been blamed for acidity, but analysis shows they are only mildly acidic, with a pH of 6.2.Feeding There are two methods of adding matter to the bin. Top feeding — organic matter is placed directly on top of the existing layer of bedding in a bin and then covered with another layer of bedding. This is repeated every time the bin is fed. Pocket feeding — a top layer of bedding is maintained and food is buried beneath. The location of the food is changed each time, rotating around the bin to give the worms time to decompose the food in the previously fed pockets. The top layer of bedding is replenished as necessary. Vermicomposters often use a combination of both methods. Sometimes unburied food can attract fruit flies, so food should be buried under at least one inch of bedding material. Harvesting Vermicompost is ready for harvest when it contains few to no scraps of uneaten food or bedding. Even a properly composted mixture will contain large items that should be discarded, such as peach or date pits, glassine-like sheets from melon skins, and twigs. Small seeds from composted food such as tomatoes and apples cannot be removed from the vermicompost and may sprout later in the seed-starting pots or garden. There are several methods of harvesting, depending on the purpose for which the vermicompost will be used, and whether or not the composter wishes to salvage as many worms and worm eggs as possible from the vermicompost. Vermicompost properties Vermicompost, also known as worm castings and vermicast, is richer in many nutrients than compost produced by other composting methods. It is also rich in microbial life which helps break down nutrients already present in the soil into plant-available forms. Unlike other compost, worm castings also contain worm mucus which keeps nutrients from washing away with the first watering and holds moisture better than plain soil. For this reason, some fruit and seed pits are reported to germinate in vermicompost easily. Vermicompost made from ordinary kitchen scraps will contain small seeds, especially those of tomatoes, peppers, and eggplants, that may sprout weeks later. Vermicompost benefits soil by improving its physical structure; enriching soil in micro-organisms, adding plant hormones such as auxins and gibberellic acid, and adding enzymes such as phosphatase and cellulase; attracting deep-burrowing earthworms already present in the soil; improving water holding capacity; enhancing germination, plant growth, and crop yield; and improving root growth and structure. Vermicompost can be used to make compost tea (worm tea), by mixing some vermicompost in water and steeping for a number of hours or days. The resulting liquid is used as a fertilizer. The dark brown waste liquid that drains into the bottom of some vermicomposting systems, as water-rich foods break down, is also excellent as fertilizer. However, the pH and nutrient contents of these liquids (as well as vermicompost) varies, depending on the food fed to the worms and whether or not lime has been added to the system. pH and nitrogen, phosphorus, and potassium (NPK) measurements should be taken periodically to determine the fertilizer composition before use. Home kits for testing are sold in hardware stores and nurseries. Problems Odor, usually due to overabundance of "greens" (wet waste) in the bin, results from too much nitrogen combining with hydrogen to form ammonia. To neutralize the odors, add a fair amount of shredded newspaper or other "browns" to the mix to absorb excess moisture, remove the smelly waste, and stop adding food to the bin until a substantial portion of the uneaten food has been turned into compost. The carbon will balance the nitrogen and form a compound that is not smelly. The higher level of carbon means that decomposition will be slower. Also, always add new material deep in the bin to disallow access to would-be pests. Consistently doing so will greatly reduce any nuisance from odor and undesirable organisms. Worms and fruit fly eggs under the lid of a home worm bin. Pests such as rodents and flies may be attracted by certain materials and odors, especially lots of kitchen waste and especially meat. This problem is largely avoided if a sealed bin is used where the pests cannot access the material, although many proponents recommend having ample access to air. This promotes natural decomposition, as worms and beneficial bacteria require oxygen. Fruit flies are common in warm weather if the food is not thoroughly covered with bedding.
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