No-till agriculture

Tillage is the turning over of 15cm to 25cm of surface soil before planting. It loosens and removes plant residues but leaves the soil bare, exposed and lost to water and wind.

In contrast, no-till farming is the practice of leaving the soil surface and structure intact when planting. This leaves the crop residue on the soil surface which protects the soil. 

Traditional agriculture is focused on intensive tillage (e.g. ripping and ploughing) and monoculture. Coupled with the use of synthetic fertilisers, burning, deforestation and toxic chemicals, tillage has led to environmental degradation, loss of soil fertility and declining crop performance and yield. Fortunately, there is a return to more sustainable methods of farming and practices that builds soil structure and health.

No-till farming is one of three principles of building healthy, alive soil. Two other practices - soil cover and crop diversity - add to building an ecosystem that includes soil microbes and beneficial insects.

Principles of no-till

No-till is about minimal soil disturbance - less than 20% - during preparation and planting. It also helps with proper placement of seed and fertiliser, explains Dr Johann Strauss, senior scientist, Western Cape Department of Agriculture.

'Ploughing destroys soil structure (which helps retain moisture and carbon) and the habitat of microorganisms.'

Non-tilled soil is rather like a sponge. The unbroken soil structure is held together by an intricate network of channels and soil aggregates which facilitate water retention, aeration and root penetration.

Improving soil structure and managing soil cover increase water absorption and deeper infiltration which reduces runoff of water and subsequent loss of soil. Mulch as a soil cover reduces soil temperature by about 4°C and reduces erosion.

Benefits of no-till

Long-term no-till crop rotation trials conducted by the Directorate: Plant Sciences of the Western Cape Department of Agriculture, have shown lower inputs and higher and more stable production (in wheat).

It has also shown that this agricultural practice captures more carbon in the soil, reducing the effects of global warming. Other benefits shown in the trials include reduced soil erosion, better water infiltration and soil moisture content throughout the growing season as well as reduced fuel cost and tractor hours.

Which crops?

No-till is suitable for all annual crops such as wheat and maize as well as perennial pastures. 'No-till farming can be employed everywhere, but soil analysis is advised to determine compaction and acidity,' Dr Strauss says.

'Employing no-till on the sandy soil of the Western Free State and soils with a high water table can be more challenging.'

No-till can ideally be combined with adding organic matter into the soil as well as the use of mulch.

In practice, specialised no-till equipment may be needed. Farmers can choose either a tine seeder or a disk seeder. The tine seeder would need a stronger tractor than a disc seeder.

The no-till farmers' groups KwaZulu-Natal and Conservation Agriculture Western Cape may be helpful to provide additional practical advice.