Reduced Soil Disturbance in Sandy Soils Under Conservation Agriculture: A Path to Sustainable Wheat Production
Tracks
| Wednesday, July 23, 2025 |
| 4:26 PM - 4:38 PM |
Overview
Speaker
Mr Ernst Smit
Scientist: Cropping Systems
Department of Agriculture Western Cape
Reduced Soil Disturbance in Sandy Soils Under Conservation Agriculture: A Path to Sustainable Wheat Production
Abstract
Sandveld farmers in the Western Cape, South Africa, face significant sustainability challenges due to climate change, high input costs, and poor soil quality. To address these issues, many have adopted conservation agriculture (CA). However, despite this shift, disc planters remain underutilized, and various tillage practices persist. The region’s sandy soils, with clay content below 5% and carbon content under 0.5%, are highly vulnerable to degradation and wind erosion. This study aims to determine whether reducing soil disturbance can enhance the sustainability of wheat production in these fragile soils.
A long-term trial (2018–2024, ongoing) was established near Hopefield, Western Cape, using a six-year crop rotation (Wheat, Cover Crop, Canola, Wheat, Oats, Lupins), with each crop represented annually. Three tillage treatments were compared: no-till, deep ripping (400 mm) every six years, and deep ripping every three years. Additionally, two seeding methods—tine-drill and disc-drill—were tested. Each treatment (six crops, two planters, and three tillage methods) was replicated three times, resulting in a total of 108 plots.
Preliminary results indicate that tillage and seeding method have not significantly influenced soil chemical composition, wheat yield, or quality. However, the high fuel costs and environmental impact of tillage highlight the advantages of no-till with a disc-drill. This system not only eliminates the need for deep ripping but also reduces fuel consumption and increases planting efficiency compared to tine-drills. Over time, additional benefits such as improved soil structure, increased microbial activity, and enhanced resilience to climate variability may further support its adoption.
By demonstrating the long-term viability of reduced soil disturbance, this research contributes to global efforts in promoting sustainable agriculture on sandy soils while offering practical solutions for farmers facing economic and environmental pressures
A long-term trial (2018–2024, ongoing) was established near Hopefield, Western Cape, using a six-year crop rotation (Wheat, Cover Crop, Canola, Wheat, Oats, Lupins), with each crop represented annually. Three tillage treatments were compared: no-till, deep ripping (400 mm) every six years, and deep ripping every three years. Additionally, two seeding methods—tine-drill and disc-drill—were tested. Each treatment (six crops, two planters, and three tillage methods) was replicated three times, resulting in a total of 108 plots.
Preliminary results indicate that tillage and seeding method have not significantly influenced soil chemical composition, wheat yield, or quality. However, the high fuel costs and environmental impact of tillage highlight the advantages of no-till with a disc-drill. This system not only eliminates the need for deep ripping but also reduces fuel consumption and increases planting efficiency compared to tine-drills. Over time, additional benefits such as improved soil structure, increased microbial activity, and enhanced resilience to climate variability may further support its adoption.
By demonstrating the long-term viability of reduced soil disturbance, this research contributes to global efforts in promoting sustainable agriculture on sandy soils while offering practical solutions for farmers facing economic and environmental pressures
Biography
Ernst Hendrik Smit, known as Rens, is a Scientist: Cropping Systems with the Western Cape Department of Agriculture, based at the Langgewens Research Farm. Born and raised on a farm between Redelinghuys and Piketberg, Rens developed a deep-rooted passion for agriculture from a young age. Today, his work focuses on long-term conservation agriculture systems, especially in dryland cropping environments with sandy and marginal soils. He collaborates closely with producers to analyse on-farm data, refine practices, and promote sustainable, cost-effective solutions. Rens also serves on the board of Conservation Agriculture Western Cape (CAWC), supporting farmer-driven research and knowledge exchange.
Rens has a strong interest in integrating legumes, cover crops, and livestock into cropping systems to enhance ecological function and farm resilience. At Langgewens, he has shown how medics and strategic grazing can reduce weed pressure, boost soil carbon, and eliminate the need for insecticides. He is also exploring the role of drone technology in improving the efficiency and precision of crop protection. With a practical, systems-thinking mindset and a passion rooted in lifelong experience, Rens brings valuable insight into building resilient farming systems on sandy soils.
