What Is Compost?
In nature, organic material will gradually decompose and return nutrients back to the soil. Many back yard compost piles are simply doing just that- piling up waste outdoors and waiting a year or more for it to decompose. However, a more readily accepted definition of the composting process is the controlled degradation of organic materials whereby we facilitate the natural microbial metabolism by providing an environment in which they can thrive. The result will be an environmentally friendly organic matter that is biologically stable and humas-rich, is suitable for growing plants, and will pose no hazard to health and the environment. Compost is a key ingredient in organic farming, and indeed anywhere that the soil’s nutrients and organic material has been depleated by long term use with chemical fertilizers. Modern, methodical composting is a multi-step, closely monitored process with measured inputs of water, air and carbon- and nitrogen-rich materials. The decomposition process is aided by shredding the plant matter, adding water and ensuring proper aeration. Aerobic bacteria manage the chemical process by converting the inputs into heat, carbon dioxide and ammonium. Any ammonium is further refined by bacteria into plant-nourishing nitrites and nitrates.
Compost can be rich in nutrients. It is used in gardens, landscaping, horticulture, and
agriculture. The compost itself is beneficial for the land in many ways, including as a
soil conditioner, a fertilizer, addition of vital humus or humic acids, and as a natural
pesticide for soil. In ecosystems, compost is useful for erosion control, land and stream
reclamation, wetland construction, and as landfill cover (see compost uses below).
Compost improves plant and soil health which results from the breakdown of brown,
carbon-rich, and green, nitrogen-rich, materials. Compost returns these and other
nutrients to the soil when it’s used as mulch, natural fertilizer, and soil amendment. Its
organic content specifically improves soil drainage, fertility and structure. Consequently,
soil holds together better, and resists erosion and runoff. And better aggregated
and clumped soil encourages better arrangements of air and water pore spaces. Soil
consequently is less compacted; and holds water for better infiltration and percolation.
Compost enables plants. to have better and quicker access to necessary nutrients and
water. It does this without increasing chemical dependency on yet another artificial,
commercial, conventional, synthetic product. And it also helps conserve water and other
resources because organic matter-rich compost holds, handles and directs water in more
Is compost a good growing medium?
The main use of compost is to loosen the soil and provide a medium whereby the
nutrients provided by the compost are made more readily available to the soil. It also
provides better moisture control to the mixed medium. Using compost by itself is not
recommended for these reasons.
Is compost safe to use?
Good quality compost will have no bad odor (pleasant, earthy smell) and should have no
recognizable pieces in it – no wood chips, no twigs, no leaves, no clumps of “stuff.” It
should look like good, rich soil. Good quality compost is heated during the composting
process to a point that most diseases are killed during the process.
Uses for Compost
- Gardening: If you have not used compost in your garden before, you should begin by spreading two to three inches on top of the soil and then tilling it in. Subsequent annual treatments are recommended, but with a lower amount of compost. Even in poor soil, the balance of compost to soil should be no more than 30% by volume.Transplant mix: Mix good soil with 30% to 50% compost to give the seeds and resulting seedlings a good start. The nitrogen and other nutrient value in the compost will boost germination and early growth without the danger of over-feeding which can come from application of fertilizer in these early and sensitive stages.
Bedding mixes. Compost can be mixed with sand, clay, aged sawdust, and other materials to create an enriched mix for landscape beds or raised-bed gardens. Compost should be no more than 30 percent of the total mix. Use a high quality mature compost to avoid nutrient and oxygen competition with plants.
Container mixes Like bedding mixes, compost isbeneficial ingredient in potting media, used up to 30 percent of the total mix, depending on salinity and maturity. It is considered a partial substitute for peat moss, but generally lacks the porosity and water-holding capacity of peat so must be used in limited percentages. The nutrient content of compost can also reduce the need for supplement chemical fertilizers, although this has to be determined in each situation.
Foundation plantings Excavated areas around the foundation of new buildings are backfilled when construction is complete, but these planting zones may contain rubble, residues of toxic chemicals, and other undesirable substances. Removing the backfill and replacing it with a soil/compost mix will improve soil structure and give foundation plantings a healthier start.
Mulch/weed control Two or more inches of compost can be used alone or in conjunction with conventional mulch products to keep root zones cool, conserve moisture, and act as a slow-release fertilizer, provided the product is course textured and mature. For a weed barrier, double or triple the depth of compost can be used, placed on top of a thick layer of newspapers, to replace geomembrane weed barriers. This is obviously only true if the compost is weed free; many are not.
Trees and shrubs: Mix well aged compost with the native soil and use as backfill when planting trees and shrubs. Immature composts may cause settling and young root disturbance due to oxygen deprivation. Seasonally, top dress with compost to the drip line and rake into the soil.
Erosion: Topsoil loss is a serious planetary issue. The use of compost to control sediment run-off and fight erosion is a relatively new technology, now being adopted by local authorities, developers, farmers, and other major disturbers of soil as another tool to reduce topsoil loss.
Compost blankets: A layer of compost spread over a disturbed area of soil is called a compost blanket. With a high water-holding capacity, compost is not tilled into the soil but remains on the surface to temper the impact of rainfall. Even small amounts can help, but typical recommendations call for a 5 cm (2 in.) layer to insure adequate surface coverage.