Compost can be used as a mulch that is placed around developing plants. Some gardeners will try to work it into the ground, but that is unnecessary as the compost will become one with the soil over time and add to the humus content. Often incompletely composted can be useful; for example, material such as mixed or ground up leaves or straw which is fresh or partially decayed. We will say more about the use of various mulches in a later post and note their value especially in seeding of uncultivated soils.
Compost is mainly plant-derived organic matter that has been decomposed. If properly prepared, it serves both as a fertilizer and soil amendment. The process of decomposing accumulated garden waste, weeds, seeds, leaves and other organic matter can be hastened by adding water to keep the pile wet and by turning the pile now and then to assure that air enters the pile. Composting can be fast or slow and can generally be accomplished over several months to a year.
Worms, fungi and bacteria generally work together in a compost pile to convert complex forms of carbon and nitrogen in the organic matter into carbon dioxide and ammonia. Importantly, much of the ammonia is then converted by oxygen-requiring bacteria into plant-nourishing nitrites and nitrates. In this manner, a large pile of organic matter will be converted to a small pile containing a nitrogen fertilizer, humus and other materials which together condition the soil and also act as a natural pesticide. Compost is prepared most efficiently when the carbon: nitrogen ratio in the compost bin is about 30:1. A composting mixture prepared from one part leaves and one part grasses, weeds and spent vegetable plants can be just about right.
Composting can be done in a very simple way such as by throwing organic matter onto the ground, piling more and more organic matter on top and then turning the pile from time to time until the compost is cooked—thereafter spreading it into a nearby plot in which the garden will be planted. Alternatively, one can use a turning drum to which organic matter is added, opening it to the air and turning the contents now and then. One may also prepare compost in multiple bins, which at least has the appearance of being more organized. In other words, you can take a simple approach or you can turn it into big project. In my view, farmers and gardeners often work too hard to prepare compost.
In the multiple bin approach, add large plants and plant pieces, weeds, seeds, leaves and other organic matter to the first bin where first stage of decomposition begins. Kitchen scraps can be added remembering that fruits and the smell of meat will attract rats and animals like racoons. The 1st bin is usually the largest bin. In general, garden materials will be added continuously over the season. The larger plant fragments (whole plants, woody stems, etc…) will be mixed with smaller fragments, weeds and leaves. Then the pile is turned, and then turned again later. After a while smaller, partially decomposed fragments are moved from the first to the second bin. New large plant fragments can then be added to the first bin. Decomposition continues in both bins, and materials are turned several times during the summer months. As composting in the second bin nears completion, material is sieved into the third bin, where decomposition continues. The piles in all three bins continue to be turned during summer and early fall—and far less often, if at all, in winter. The compost accumulating in the third bin is near ready for use, but can often be turned and composted further.
If organic matter is added at the end of the growing season with leaves and weeds added in the fall, a fair amount of compost will be generated as the pile is worked in the spring, but the total amount of compost generated may still be insufficient to service all gardening needs. As the weather warms over the spring, one usually begins from bin number 3. Place the compost from bin number 3 on the soil between the plants using it as mulch at first. Then, over the next weeks, this initial layer of compost will to some extent work its way into the soil. Around the major plants you can add another layer of compost using it to cover over exposed soil. The compost will impart new nitrogen into the soil and also to assist the soil in holding its moisture.
Some gardeners add animal manure (chicken, horse, and cow) to their compost and also some soil and a little crushed limestone. A few chickens walking through before seeds are planted can accomplish the the same ends. Some lime may be necessary to add to compost especially if we large quantities of leaves are added to the compost in the fall. Compost derived from some types of leaves can render the soil acidic. The lime will counter this effect.
Without the addition of manure, compost may not provide enough nitrogen to our garden soil. You can alternatively amend the nitrogen content of the soil by planting a legume (rye, clover or soybean) in the fall after you have cleaned up your plot. These kinds of plants (and others like them) will impart added nitrogen to the soil—if you’ve planted some regular bush beans, you already have a leg up.