We take it for granted that when we use the term “soil” we assume everyone knows what it is. Soil has four main components – a mineral component of up to 45%, and air and water each of up to 25%, and the remaining 5% is made up organic matter.
Soil organic matter (SOM) consists of three primary parts including small (fresh) plant residues, macro and micro living soil organisms, decomposing (active) organic matter, and stable organic matter (humus). The mineral component of the soil can be lifted into the life sphere through its relationship, at molecular level, with the SOM. All soils have a mineral aspect, a chemical aspect and a biological aspect. The relationship between these aspects determines fertility and health.
The organic farmer works with the SOM content influencing soil regeneration, soil structure and soil fertility and health.
a. Cover crops
In agriculture, cover crops are plants that are planted to cover the soil rather than for the purpose of being harvested. Cover crops address soil erosion, soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in an agroecosystem, —an ecological system, managed and shaped by humans.
Cover crops may be an out of season crop planted after harvesting the cash crop. They may grow over winter and can include grasses grains legumes and clovers.
b. Crop rotations
Crop rotation is the technique of planting crops in a different area of the land so that no single crop will be planted in the same place two—or more—years in a row. Crop rotation is said to be the practice of planting different crops sequentially on the same plot of land leading to improve soil health, optimise nutrients in the soil, and combat pest and weed pressure.
As an example, when the maize harvest is finished, beans might be planted, since maize consumes a lot of nitrogen and beans return nitrogen to the soil. A very simple rotation is planting a crop above the soil and then one below the soil.
Decomposed and humified organic material used as a fertility amendment in agricultural production, produced by a combination of actions over time by microbes, invertebrates, temperature, and other elemental factors (e.g., moisture content, aeration). Composted material shows practically no substantive indication as to the original substrate(s) from which it was made when it is in the humus phase.