Deeper soil,superior root systems

Soilmix Africa is breaking all the limits on crops’ root systems, from annual grains to perennial orchards. Their machine mixes and homogenises soil to a depth of 1,2m, compared to an ordinary plough’s 20cm and also applies a cutting-edge soil correction programme. Mastermind Koos Stofberg, a winemaker and soil preparation expert, spoke to Glenneis Kriel.
Issue date : 01 May 2009

- Advertisement -

Soilmix Africa is breaking all the limits on crops’ root systems, from annual grains to perennial orchards. Their machine mixes and homogenises soil to a depth of 1,2m, compared to an ordinary plough’s 20cm and also applies a cutting-edge soil correction programme. Mastermind Koos Stofberg, a winemaker and soil preparation expert, spoke to Glenneis Kriel.

“Very few improvements have been made to the action of the plough on the soil since the Egyptians first used it over 4 000 years ago,” says Koos Stofberg of Soilmix Africa. “My experience as winemaker and soil preparation specialist prompted me to find more innovative ways to mix the soil, which lead to the design of the Soilmix machine.”
This machine mixes the soil into a homogeneous medium up to a depth of 1,2m. The roots of newly planted crops grow more densely and over a wider area than in soil with layers and variation as is typical in South Africa. Plant roots usually only grow in one layer, so their growth is stunted and crops often suffer,” Koos explains. Conventionally, farmers matched crops with specific soils, but with the need for increased production they have had to manipulate the soil to meet the crop’s requirements.

Koos explains growth above the soil reflects what’s going on below the surface: a plant will produce a much better-quality product and higher yield with a healthy, dense root system. Perennials, such as grapes, citrus and deciduous fruit and olives, will start producing sooner with good roots. A fruit tree, for example, might abort fruit if its root system is underdeveloped.Good root systems make annual crops such as maize and wheat stronger and more resistant to environmental stresses like wind, flood or drought damage.

- Advertisement -

Deeper maize and wheat roots
“Many farmers’ maize only grows as deep as they plough, and is sensitive to drought stress,” Koos says. A University of Pretoria study compared maize in soil homogenised to a depth of 1,2m and in soil ploughed to a depth of 15cm to 20cm. The maize roots planted in the deep soil were denser and penetrated more deeply, while roots in the control remained in the top 15cm to 20cm. Maize heads were almost four times larger and yields almost doubled in the deep soil.
“A deeper rooting zone boosts yield and quality over many years,” says Koos. “Farmers only have to return to the lands when compaction becomes a problem.” This compensates for wheat and maize farmers’ reluctance to spend on inputs. “They reason they won’t suffer a major loss in a poor year and will profit in a favourable year by keeping inputs low,” says Koos.

In established orchards
The Soilmix machine can also be used in established orchards and plantations.
“Farmers worldwide are harvesting poor yields and poor-quality fruit because they didn’t correct the soil before establishing new orchards,” says Koos. “They usually apply vast amounts of nitrogen when crops get ‘stuck’, acidifying the soil.” Correcting calcium and phosphate levels is also difficult once an orchard has been established, as they’re highly immobile in the soil. The Soilmix machine works the minerals thoroughly into the soil, to the full 1,2m depth. Its compact design, only 2,2m wide, lets it move through and under, say, table grape rows without damaging the vines.
The machine also helps with root pruning, stimulating root growth and vigour. “If a root is trimmed, three to five new roots will develop,” says Koos. “These can grow more than 1m in as little as six months under favourable soil conditions.”

A study by Prof Eben Archer from Lusan Premium Wines in Stellenbosch found the Soilmix machine increased the number of hair roots fourfold compared to traditional ripping and ploughing, significantly improving grape production and quality.
The machine is used on every second row, and on the alternating rows a year or two later, once the root system has regrown. It’s proven this doesn’t reduce yield in the first year and increases yield thereafter. “Together, root pruning and mineral adjustment can increase yield by 30% to 40% for up to four seasons after the minerals are mixed into the soil. Compare that with the cost of replacing an established orchard,” Koos says.

Soilmix at your service
The Soilmix machine is said to be much gentler on the soil than a rotavator, which mixes the soil by cutting through it. The rotavator’s blades are in constant contact with the soil. With Soilmix, more than 90% of the mixing is by soil-on-soil action.
Koos admits the machine isn’t a miracle cure, but part of a holistic approach to improving soil. Soilmix Africa also offers soil correction services in combination with soilmixing. The service includes Geographical Positioning System (GPS) mapping of soil variation and area-specific requirements. Soil is analysed by accredited laboratories, and aims to correct both macro- and micronutrients. Koos uses the SsTools programme to guide nutrient applications. “Farmers can’t afford to treat all their lands with the same recipe,” he explains. “You have to identify each area’s needs and treat it accordingly.”

Soilmix Africa helped design an instrument to take core measurements to determine soil depth and structure, guiding the depth to which the Soilmix machine should be used. “We usually only mix the soil to the depth where there’s clay,” Koos explains.
After the nutrients and organic material have been applied, Koos works them into the soil. The end result is a homogenised soil medium with evenly dispersed nutrients. Koos adds that organic material worked into the soil breaks down much more efficiently than if it’s simply left on top of the soil.Contact Koos Stofberg on (021) 882 8270 or e-mail [email protected]

More about the Soilmix machine

The Soilmix machine has a 430kW engine, compared to the 290kW engine of a D9 Bulldozer. The final prototype weighs 25t and runs on tracks.
The machine has a hydraulically driven drum that’s lowered into the soil by a hydraulic actuator, and is fitted with eight discs fitted with tungsten-carbide cutting tips for mixing the soil. Koos says the final version of the machine will be adjusted so that the depth of mixing follows GPS information. “At the moment we take various soil profile samples and physically adjust the depth of soil mixing accordingly. However, the final machine would be able to make these adjustments by itself.”

Koos is currently acquiring financing to build new machines, and expand services in South Africa and into South America and Saudi Arabia, where there’s a lot of interest in the machine. He explains that using the Soilmix machine in combination with scientifically based recommendations promises to significantly improve yield and crop quality anywhere in the world where compaction is a problem.