Soil – our most precious Resource
Soon, we will need to move from an oil economy to a bio-economy if we are to fight the challenges of climate change and oil depletion. So, as we devise methods to obtain much more of our energy from the sun mainly via the original solar panel-the plant leaf, it is vital that we do not do so by degrading our soil, something that is happening much too quickly anyway.
Until around 70 years ago, in Europe at least, cereal crops such as wheat, barley and oats were harvested intact by binding, with most of the above ground biomass removed from the field. After threshing, the grain was used for human and animal feed and the straw for animal bedding.
The animal manure and human waste was returned to the soil in due course and so the soil nutrients were constantly recycled.
That cycle has long been broken. The nutrients are now flushed down the sewers of the great cities or treated as a waste product at huge feedlots, hundreds of miles away from their origin, but at least some of the straw remains on the soil to help organic matter levels.
In modern farming we now replace the lost nutrients with fertiliser made, or mined and transported, using finite fossil fuels. This oil and gas (for N fertiliser) dependent farming system is plainly doomed to fail as oil and gas supplies deplete and as their use causes climatic change severely disruptive to farming.
A new farming system that again removes most of the above ground biomass to produce the food, fuel and chemicals needed in the post oil era will need to be carefully planned.
By removing the entire crop, just as was done in the past, crop residue levels would be low making no-till or minimal till easier. Keeping the roots and stubble near the surface helps prevent erosion and slows decay, compared with energy hungry deep tillage, so soil structure remains good.
So far as soil nutrients go, they don’t generally disappear and the trick is to return them to the soil.
Ideally, crops should be used locally by being processed at a local integrated bio refinery where all of the components are used to produce food, fuel, chemicals and process heat.
If some of the grain were used for ethanol production, the brewers grains would be fed to animals, then the manure would produce biogas, leaving a residue containing soil nutrients that would be returned to the soil. Even sewage sludge should be digested to provide energy and fertiliser.
As nitrogen fertiliser production is the biggest use of energy in most farming systems, heavy government investment should be made in to high yielding legume plants that can fix nitrogen and be an important part of maintaining soil fertility as well as providing vegetable protein to partly reduce our meat consumption.
Comments
Leave a Reply
Buy Famine in the West Printed Book £6.49 +pp
Buy Famine in the West Ebook £2.99
Twitter
