The thin mantle of Soil that covers our Earth is what feeds and nurtures us. We are innately and inextricably connected to soil for our survival, for like humans it contains the universal life-force without which we would not survive.
Only a fertile soil contains the billions of amazing and diverse creatures and microbes, from earthworms to fungi, which provide the energy that drives our food systems.
A square metre of good healthy rich soil can contain up to 7 billion living organisms which are the “workers” in the “factory” of soil. It is this soil that yields healthy plants which cleanse our air, produce our oxygen, feed us and our animals, and is the most important resource of every farm, smallholding and suburban home.
Improving and maintaining the fertility of the soil is the central focus in Natural, Ecological, Biological, Sustainable and Organic farming.
Feed the soil, not the plant
Feeding the crop begins with feeding the soil first, for the plant has been designed to feed itself- hence no human assistance or intervention is required in our wild areas, forests, Fynbos, savannah lands, bushveld etc.
As long as soil fertility is measured only by the crop yields, awareness about the soil will remain low. Soil in this context is just a medium where plants grow and is a base to apply plant fertilisers, normally in a chemical format- and the resultant food crops are low in nutrition and vulnerable to pests and disease.
A quote from Gary F. Zimmer in his book ‘The Biological Farmer’:
“Agronomists and soil scientists have written that at least 16 elements are needed to grow plants, and the productivity of a soil can never be greater than the plant food element in least supply. Soil is a complex mixture of several components, capable of supporting plant life. Typical soils contain minerals, water, air , organic matter & living organisms. Not all the minerals are available to plants at one time, as most in typical soil are “locked up” in the molecules of the mineral particles, and this is the Biological farmers secret. Through soil structure changes, large root systems and biological activity, the farmer can help nature release some of those tied up minerals. You need to make these nutrients “exchangeable” or available to the roots of the plant, because nutrients interact and an excess of some elements can cause a shortage of others, even though it appears there is enough on a soil test”.
At least 16 macro and micro elements needed
Following the “Law of Return” assists the maintenance of soil fertility by retaining as a minimum the 16 macro and micro elements (there are more), as well as assisting and encouraging the billions of micro-organisms to be present.
The Law of Return states: Whatever is taken out of the soil must be returned in equal measure.
How? Imagine starting with virgin land in a balanced state with all of the macro and micro nutrients present, in crucial ratios and relationships to each other. Thereafter every weeding, clearing, harvesting and pruning action removes those nutrients .
The Law of Return states that these nutrients, in the quantities taken away, must be returned in order to maintain a balanced ecological state and fertile soil.
Agro-chemical farming misses the boat
Agro-chemical farming methods return at best 3 or 4 nutrients (fertilizers in a chemical format) into the soil. (NPK mostly- foliar feeds do not count) The other 13 plus are eventually removed totally, and are missing in the “food” grown there.
A quote from ‘The Soul of Soil’ by Grace Gershuny and Joe Smillie:
“The basic aim of ecological soil management is to provide hospitable conditions for life within the soil. Sustainable agriculture aims to protect the soils ability to regenerate nutrients lost when the crops are harvested- without dependence on “off-farm” fertilizers. This depends on the diversity, health and vitality of the organisms that live, grow, reproduce and die in the soil. Through the activities of these soil microbes the basic raw materials needed by plants are made available at the right time, and in the right form and amount.”
In my view the most important replenishment actions are:
- Application of rich compost full of diversity replacing those nutrients taken away. The plant decides how much to take up and when.
- Intercropping and companion planting brings diversity, supplies carbon, fulfills an integrated pest management role, provides a green mulch which keeps soil cool and moist, and outcompetes weeds.
- Dry mulching covers the soil, supplies a cool and moist habitat for the soil micro-organisms, as well as suppressing weed growth.
By Liz Eglington