I’ve just finished reading an excellent book by Michael Pollan entitled; The Omnivores Dilemma, the search for a perfect meal in a Fast Food World. In this book Pollan follows his next meal from land to table, tracing the origin of everything consumed and the implications for ourselves and our planet.
In one section he discusses the shortfalls of farming systems where plant nutrition is reduced to the application of simple artificial fertilizers as opposed to organic systems where soil fertility is increased using compost and manure like we do on the farm at Posada del Valle.
Turning compost in the winter and letting the soil biology work
It was the German chemist called Liebig who set agriculture on its industrial path when he broke down the quasi-mystical concept of fertility in soil into a straightforward inventory of the chemical elements plants require for growth. At a stroke, soil biology gave way to soil chemistry, and specifically to the three chemical nutrients Liebig highlighted as crucial to plant growth: Nitrogen, Phosphorus and Potassium or to use these elements from the periodic table N-P-K. I studied horticulture at Bath University in the 70’s and we had plenty of classes on soil chemistry but never anything on soil biology, a reflection of this thinking.
The N-P-K mentality embraces a good deal more than fertilizer; it fosters the wholesale reimaging of soil (and with it agriculture) from a living system to a kind of machine. Apply inputs of NPK at one end and you get yields of crop at the other. Since treating the soil as a machine seemed to work well enough, at least in the short term, there no longer seemed to worry about such quaint things as earthworms and humus.
But as we have come to realize on the farm at Posada del Valle there is a huge biological process involved in plant nutrition a sin fin of symbiotic realtions between billions of big and small organisms that inhabit a spoonful of earth some of which can be seen when we turn the compost.
Leaves decomposing on the soil surface
Rather than reducing farming to the application of a few “essential” elements we should be imitating whole natural systems as seen in the forest and prairie. Leaves drop from the trees and decompose on the soil surface; hence we apply our compost on the soil surface and don’t dig it in. Bare soil is rarely found in nature so we avoid it by sowing a cover crop. As opposed to thinking in lineal systems like a machine which takes in resources and spews out goods we need to be thinking in loop systems. A simple example of this is crop waste which we don’t treat as waste but use it to make compost which produces more crops.
Imitating natural systems may sound more like philosophy than science but mimicking natural process precedes the understanding of them. When working in the vegetable garden certain things just “feel” right and with time many of these feelings have been proved to be true: plants grown on composted soils are more nourishing than plants grown in synthetically fertilized soils and such plants are more resistant to disease and insect pests. We have so much to learn from nature!
Healthy and tasty food grown on vegetable garden and "fertilzed" with compost.
No comments:
Post a Comment