Changing the potential of your soil

By building soil carbon levels, farmers can improve the resilience of their crops, reduce the use of chemical pesticides and fertiliser, and buffer their crops against extreme weather. Glenneis Kriel reports.

- Glenneis Krie

What are you farming? You may say fruit, grain, vegetables, livestock or pasture, but stripped to the bare essence, everybody is actually farming carbon to nitrogen, or more specifically, the soil. This was the message of Nico Uys, operations manager of Ezolimo Organics, at the SA Olive Field Day, held near Wellington in the Western Cape in January.

Uys said most of South Africa's soil had a carbon content of less than 0,5%, which means farmers are heavily dependent on external inputs to produce crops. However, by increasing the carbon content of soil, farmers can improve the chemical, biological and physical structure of the soil, which translates into huge cost savings by improving nutrient retention and reducing the vulnerability of crops to pests and diseases.

Such an improvement also renders crops less vulnerable to climate shocks. The soil becomes like a sponge that is better able to handle rain during the rainy season, less prone to erosion and topsoil washing away during heavy rains, and able to hold more water during dry months. Uys referred to research that found that the soil's water-holding capacity could almost be doubled with every 1% increase in carbon. For instance, the water-holding capacity of 100kg soil could increase from 20 to 40 if the carbon content of this soil were increased from 1% to 2%. It would increase to 2000 if the carbon content of this soil was raised to 5%.

"South African farmers should aim to build their soil carbon levels to between 2% and 2,5%. Higher levels have been achieved in Mpumalanga and Limpopo, but it is difficult in drier parts of the country. Levels of up to 5% have been achieved in some wetter and cooler parts of the world."

BUILDING SOIL CARBON LEVELS