Composting has a lot of benefits. It puts waste from farm, home and garden to good use; it produces highly nutritious organic matter for those same farms and gardens. It reduces or even eliminates carbon releases into the atmophere. And in fact, the University of Missouri is using it in what they envision could eventually be a zero-carbon production system that services campus dining halls.
MU points out Americans now waste 150 trillion calories a year in the form of discarded food. With their system, that food from the dorms and offices goes right back into the production system. In addition to food waste from Campus Dining, the closed-loop composting system uses horse bedding from the Bradford Research Center just east of the Columbia campus.
It’s not perfect; Campus Dining yields 270 tons of food waste a year, but only a fraction of that is composted at Bradford. And even with that, the farm produces more compost than it can use to grow the vegetables that get shipped back to the dining halls. They’re hoping the students who run the composter can find a way to profitably market the rest.
Composting, according to a University of Arkansas Extension website, is controlling the natural decay of organic matter by providing the right conditions for organisms to convert the feedstock into a product that can be returned to a growing system. Bacteria, fungi and protozoa break down the feedstock in a moist, oxygen-demanding environment.
The article says compost makes soils better. It breaks up heavy clay soils, helps sandy soils retain water and nutrients, and releases essential nutrients. It also contains beneficial microscopic organisms that build up the soil and make nutrients available to plants.
Virtually any organic material can be used for composting, but the material’s content will contribute to the quality of the compost. The Missouri dining hall waste is mostly discarded food, which has a high ratio of nitrogen, whereas the horse bedding is high in carbon. The Arkansas article says the decomposing microorganisms need about 1 part of nitrogen for every 30 parts of carbon in the organic material; if the carbon ratio is higher, the materials will decompose more slowly. A pile made of sawdust, which is high in carbon, will take years to decay, while adding more green substances like grass and hay will produce compost in less time.
Because the composting process is aerobic, the piles should be regularly disturbed or infiltrated with pipes with holes called air stacks. The pile also needs moisture, and should be kept damp. Too much water, though, can block oxygen and slow decomposition, so piles should be covered during rainy periods.
Compost is ready when the original organic materials are no longer recognizable and it is no longer generating a significant amount of heat. It should have a dark, crumbly appearance and an earthy odor. Using it before it’s completely decomposed could cause crops to yellow and appear stressed, because the microorganisms are competing with the plants for needed nitrogen.
Like the students at MU, you may produce more compost than you need, and turn to marketing it. One farm in Dardanelle, Ark., Balloun Farms, uses an aerated static pile composting system to produce a concentrated organic compost free of any pathogens or weed seeds. Their organic compost is made from pig manure solids and carbon sources such as wheat straw and/or corn stalks. The pile temperatures are significantly higher than the minimum required to take care of weed seeds and/or any human pathogens.
