Thanks to the COVID-19 pandemic, people will no longer take the air they breathe for granted. Moreover, mankind still does not seem to fully grasp that the soil we walk and live on, also counts as an essential natural resource of life.

While it also feeds the world, soil should be treasured by protecting and preserving its organic compounds.

Geology vs soil

The United States Department of Agriculture’s (USDA) Natural Resources Conservation service, professes soil health as a living factory of macroscopic and microscopic workers that need food to eat and places to live in order to do their work. They say there are more individual organisms in a teaspoon of soil than there are people on earth – and soil is controlled by these organisms.

“Soil health is a complex matter and its central focus can be relayed as the interaction of several different physical, chemical and biological processes taking place,” says Dr Pieter Swanepoel, senior lecturer and departmental chair of Agronomy at Stellenbosch University.

Figure 1: Diversity of plants equate to a diversity of root structures with different microbial fingerprints.

“How soil is used, will determine its health. Aside from that, one must keep in mind that the presence of soil organic matter, known as soil carbon, plays a huge role in almost all the processes taking place in soil. You will be on the right track when management practices that increase the carbon in the soil, are in place.”

Dr Hendrik Smith, conservation agriculture facilitator at Grain SA, and Willie Pretorius at Soil Health Solutions, jointly agree that soil without life can be considered geology, or just plain ‘dirt’. They say that the fusion of life is what transforms ‘dirt’ into soil.

As is shown by this illustration, it is essential that ground carbon is in place. It contains soil organic matter and inorganic carbon as carbonate minerals.

Soil health indicators

The most important soil health indicators are soil organic matter and soil organic carbon, soil pH, bulk density, soil biology, cation exchange capacity, available water capacity, soil texture, soil porosity, soil aggregate stability and hydraulic conductivity.

Pretorius and Dr Smith list these principles as important for soil health:

  • Limit soil disturbance: Limit the mechanical, physical and chemical disturbance of soil. Nowhere in nature do you find mechanical tillage, but humans have found this practice an easy way to access more land faster for industrial farming, damaging the structure almost irreparably over time with the consequent erosion loss of more than three tons of topsoil for every ton of maize produced in South Africa.
  • Retain armour on the soil surface: Bare soil is a sign of a dysfunctional ecosystem.
  • Create and maintain crop diversity: Monocropping is thepractice of growing the same crop every year, though it creates serious problems for the soil microbiology. Microbial communities retained by a single crop is not diverse enough to establish a meaningful ecosystem to support the maintenance of the soil functions. Pathogens become dominant, nutrient cycling is inhibited and reliance on chemistry and tillage becomes greater.
  • Retain living roots in the soil for as long as possible during the year: The soil microbial community is dependent on exudate from living plants for their survival. Planting cover crops after harvesting of the main crop is done to not only feed these important microbes, but also to maintain diversity.
  • Grow healthy plants and animals together: The stimulation of a grazed plant will increase its photosynthesis and provide more exudates into the soil to feed the microbial population.
The differences in colour between regenerative farming methods on the left, and conventional methods on the right.

A soil ecosystem

The most vital ecosystem functions on which soil health depends are soil organic matter building, providing a habitat for soil microbiology, nutrient cycling, ability to infiltrate and store water, retain aggregates (structure) and prevent pathogen domination.

These functions and services, according to them, are all driven and regulated by soil microbes such as bacteria, fungi, protozoa, nematodes, micro-arthropods and macro-fauna such as earthworms and dung beetles, that form an interdependent ecological system.

Conventional vs regenerative

Disturbing soil properties and hence the balance of an ecological system within soil, will disturb the maintenance and provision of the soil functions and services. These disturbances include:

  • Physical soil disturbance through tillage.
  • Poor grazing practices.
  • Added chemicals.
  • Excessive fertiliser applications.

Conventional large-scale monoculture production models do not take cognisance of soil functions and use physical and chemical inputs such as tilling, herbicides, insecticides, fungicides and nematicides to provide in crop needs. All these inputs have a serious negative impact on the soil life and thus on the ability of the soil to function properly.

Balance is key

SWP Agri specialises in sustainable soil, water and plant solutions and is headed by Dawie van Rensburg. He is of the opinion that commercial farmers can get the better of the challenges they are facing, by balancing the proportions of soil chemistry, physical structure and the biology in the soil and to further maintain healthy levels of carbon.

“This must be viewed in light of the farming protocols that are presently being practised on an industrial farming scale. It limits the possibility to manipulate the proportions that nature maintains where soil is being undisturbed,” he says.

It furthermore results in functions such as water infiltration, maintenance of aggregates and the ability to store water being taken for granted, as these cannot be regulated with chemistry or other means. They become seriously limiting factors in these large-scale factory farming ventures that end up farming in ‘dirt’-based hydroponic systems. According to Pretorius and Dr Smith, this not only has serious implications for soil erosion and resource use efficiency, such as rainwater, but also affects the nutrient quality of the crops produced, with subsequent severe negative influences on human health.

This is in complete contrast to how nature provides for all living beings through an interdependency on microbiology. No living entity exists in isolation – even human beings have more microbial cells by a factor of 10 on and in their body, which maintains their health. This is true for all animals and plants.

Farm with nature

Regenerative agriculture farms with nature and uses vast amounts of free resources in its production model, which stands on five pillars: no soil disturbance, cover and build soil surface armour, create and maintain crop diversity, retain living roots in the soil for as long as possible, and grow healthy plants and animals together.

Van Rensburg believes farmers all over the world should start viewing soil health in a different light, since many of the current non-sustainable farming practices will ultimately destroy the very foundation of their livelihood. “Hence it is important to get off on the right foot with healthy soil and develop scientific practices to address its health by means of a broad holistic approach.”

Likening the aforementioned pillars of soil to a three-legged chair with carbon as the seat holding it together, Van Rensburg stresses that the legs should be in balance, mostly for safety reasons. “In the same manner, farmers will find themselves in dire straits if our planet’s soil winds up becoming unbalanced.” – Carin Venter, FarmBiz

For more information, contact Willie Pretorius on 083 458 9854 or willie@soilhealthsolutions.com; Dr Hendrik Smith on 082 331 0456 or hendrik.smith@grainsa.co.za; Dr Pieter Swanepoel on 072 112 9155 or pieterswanepoel@sun.ac.za; or Dawie van Rensburg on 082 609 7770 or dawie@swpagri.co.za.