DRiS soil data from 34 localities reshapes South African CA trials

Roughly 200 complete composite soil samples from three provinces, 15 distinct areas and 34 localities form the dataset now steering South Africa's conservation agriculture (CA) research programme. The Diagnosis and Recommendation Integrated System (DRiS), a data-driven method that analyses the chemical balance between plant and soil rather than isolated nutrient values, produced the data. Researchers presented the results at a two-day joint research forum hosted at North-West University's (NWU) Living Laboratory for Sustainable Agriculture on the Pienaarskamp research farm near Potchefstroom.

NWU, ASSET Research and the Agricultural Research Council co-hosted the forum, which draws funding chiefly from the Maize Trust. Farmers, researchers, students, academics and industry partners attended.

Why nutrient balance beats volume

Charles le Roux, commercial director of DRiS, told the forum that healthy, highly productive soils and crops depend on a strict balance of nutrients within the soil and the plant itself. "By successfully applying this principle of nutrient balancing across different soils and crops in diverse geographical production regions, we can empower farmers to optimise and accurately manage their marketable yields," he said.

Le Roux warned that reacting to visible crop deficiencies is often an expensive mistake. "By the time a plant displays physical symptoms, it may already be too late to implement cost-effective corrective action," he said. "Frequently, a problem isn't caused by a direct lack of nutrients, meaning that simply adding more inputs isn't the solution."

His central argument: optimal crop quality and marketable yield depend more on precise nutrient ratios than on high fertiliser volumes. Traditional programmes that target excessively high nutrient levels can trigger antagonistic relationships, in which an overabundance of one nutrient blocks uptake of others. A significant share of expensive chemical inputs goes to waste as a result. The DRiS algorithm quantifies these antagonistic effects, and a new cloud-based platform lets farmers upload standard laboratory reports and receive a simplified diagnostic map of their crop's limiting factors.

What did the 2025/26 season show?

Dr Hendrik Smith, CA facilitator and programme manager at ASSET Research, said every ASSET research trial now uses DRiS for soil health analysis. During the 2025/26 season, samples came from eight on-farm trials in the eastern and western summer grain production regions, plus commercial grain farms across the Mpumalanga Highveld, the eastern and north-western Free State, and North West. That data formed the basis of the forum's discussions.

"Discussing these results with a broad spectrum of stakeholders, ranging from producers and agribusiness leaders to academic researchers, was highly refreshing. It pushed everyone to view soil health from a completely new angle," Smith said. Le Roux added a blunt verdict: "The industry remains overly focused on treating symptoms rather than addressing the underlying nutritional imbalances and other soil health problems."

CA is not no-till

Cobus van Coller, a Viljoenskroon grain and livestock farmer who chairs the Conservation Agriculture Research Forum, began experimenting with these practices in 2006, when little locally relevant guidance existed. He stressed that CA is broader than no-till: it combines crop rotation, soil cover through residues or cover crops, livestock integration, and carefully judged soil disturbance.

The approach has local roots. In 1974, Viljoenskroon farmers Anthony Evans, Carel Koch and Rhys Rolfe built a ripper to break up compaction in low-clay sandy soils with minimal topsoil disturbance. Many South African farmers already use elements of CA; few apply the full suite.

Regional variation drives the research design. "The Free State, North West, and the eastern parts of South Africa have different soils, and conditions can vary even within one area such as Viljoenskroon. Practices that work on one farm may not necessarily work on another," van Coller said. Trials therefore run against conventional farming comparisons to measure soil health, organic carbon, yields and profitability.

On-farm commitment

Van Coller runs a substantial trial on his own farm at his own expense, and bought a dedicated tractor, planter and sprayer so research does not disrupt production fields. "Reliable statistics and consistent management are essential if the results are to be trusted," he said. He urged every farmer to trial practices on their own land, noting a neighbour's results are a guide, not a substitute.

Day one closed with a tour of Pienaarskamp field trials and poster presentations by final-year NWU BSc Agriculture students covering agronomy, soil science, entomology and plant nutrition. Day two reported Maize Trust-funded findings to funders, demonstrating progress to date. Van Coller's closing message was blunt: soil degradation accumulated over decades must be halted, and today's farmers carry responsibility for protecting the asset. Farmers should watch the next round of trial results as the 2025/26 dataset expands across further localities.