Soil CO2 dynamics
Most organic gardeners soon learn that the key to maximizing land fertility, is not just adding more organic matter to the soil at increased depth, to effect better crumb structure, water percolation, aeration, and total usable nutrient content. But also to increase the mulch on the surface that protects the top soil from UV sterilization from sunlight, with enough texture to prevent large rain drop compaction, as well as insulation to keep the soil temperatures lower to slow the losses of nutrients from carbon compound out gassing.
Deep woods have a built in shade canopy structure from the diversity of the blend of the under growth to top of canopy, by plant size gradients that protect the forest floor litter in order to prolong this natural mulch that results in a support mechanism for a thicker layer of small organisms, bugs, ants, worms, molds, yeasts, and fungi.
As soon as people start to farm old forest land they take away the shade canopy, till the top soil and incorporate the mulch into the top 6″, the commonly know smell of freshly tilled soil is due to fumes generated from the high death rates of soil bacteria being exposed to the killing effects of the sunlight’s full strength UV component. No or low till farming is a newer concept that avoids a lot of the problems associated with the deep plowing of the soil, it leaves the crop residue on the surface as a mulch, where it performs some of the shade and living organism support that forest litter did in the first place.
The problems due to unchecked soil erosion starts with loss of the surface mulch, as well as the overhead canopy that shelters the soil particles from rain drop impact that blasts particles loose from the soil, the organic matter loosened by this process is light and floats away on the runoff, while the fractured soil crumbs flow along the bottom, with the fine silt, and dissolved nutrients mixed thru out the murky water .
I think the people doing the plant cultivation of their own food sources are responsible for maintaining the healthy soil structure as close to what evolves naturally, by maintaining the surface mulch as well as adding organic matter to the top and sub soil horizons, thus effecting lower moisture loss, and more stable and cooler soil temperatures, and as a result more efficient nutrient to food conversion ratios from maintaining a healthy blend of soil bacteria, molds, yeasts, and fungi to effect good mycorrhizal symbiosis of the exchange of nutrients, that benefits the whole biomass, with minimal loss of out gassed carbon compounds to the atmosphere.
The recent increased use of better farming practices in the USA is one of the main reasons why as a country we are carbon emitting neutral, along with good landscaping practices in the suburban sprawl, the preservation of wetlands for the purpose of filtration of run off, and from the increasing shade canopy in urban tree plantings.
Just my $.02 Richard Holle