Human interaction with soil very often results in the release of soil carbon with adverse consequences for both soil and climate. It is vital that we understand concepts such as soil aggregation and that we change the ways that we interact with soil and soil carbon in particular. When the factors which influence soil carbon are understood and applied to cropping systems it becomes possible to produce crops in ways which firstly minimise the release of soil carbon, secondly optimise carbon draw down (through optimising plant photosynthesis) and thirdly optimise the retention of carbon in soil.
Factors which influence the retention of carbon in soil can be divided into those which influence soil biology (for example soil moisture) and those pertaining to different forms of carbon compounds in soil. I will discuss soil carbon influencing factors with reference to my own market garden which combines biochar producing stove and heating systems with a coppice producing alley cropping system, using no walk, minimum dig beds to produce mainly vegetable crops for local sale and coppice for use in the biochar producing stove systems. Rather than digging the biochar into the soil, as is usually done, it is then returned to the cropping area in a mulch.