Composting is a process where organic materials in soil are transformed into a dark rich matter referred to as humus or compost (Swartzbaugh, 1993). The process can be biological or could involve using the latest technology to aid in composting. Humus is important in soil as it enhances fertility, workability, drainage, and water retention capacity in soils.
MSW (Municipal Solid Waste) generally referred to as ‘garbage’ is an important source of organic matter to soils when treated through composting procedures. MSW majorly contains waste food, containers and packaging, batteries, old furniture, tires, and oils (Robinson, 1986). However, when introduced directly to soil without treatment, negative implications are observed. The organic portion of MSW may range between 60-70% in mass posing a risk to the environment. The portion undergoes microbial transformations in soils resulting to pollution in the air, soil, and water (Robinson, 1986, p. 21). Therefore in reducing this hazard composting is the only procedure to be implemented.
The high rate of organic matter in soil also increases in excess the content of essential macro nutrients in soil—NPK (Nitrogen, Phosphorous, and Potassium). Accelerated levels of Nitrogen in cereals-- maize, wheat and grams—results in them having reduced protein content and low quality in carbohydrates (Robinson, 1986, p. 22). The same is also noted in Potassium content where vitamin C and Carotene content in vegetable and fruits is less than normal.
Apart from organic matter, other foreign materials in raw MSW such as batteries and oils are a source of toxic substances. They may have heavy metals such as Lead, Arsenic or Cadmium. The substances influence both the soil surface and underground soil. Heavy metals on the soil surface have health effects on the farmer and in farm animals. Ingesting them result in birth defects, cancer, and organ diseases (Robinson, 1986). Furthermore, the toxic compounds in the soil can result in: low soil fertility; reduced nitrogen fixation; low crop yield; disturbance of soil flora and fauna; ease in erosion. This consequence is all due to influence of raw MSW on the physical, chemical, and biological properties of soil.
Ojha, K.. (2011). Status of MSW management system in northern India- an overview. Environment, Development and Sustainability, 13(1), 203-215. Retrieved February 25, 2011
Robinson, D., W. (1986). The Solid Waste Handbook: a practical guide. Canada: John Wiley and Sons. Pp. 21-23
Swartzbaugh, J. (1993). Recycling Equipment and Technology for Municipal Solid Waste: material recovery facilities. Ney Jersey: Noyes Data Corporation. Pp. 9-11