Soil sampling: Healthy crops start with healthy soil

Soil health is the cornerstone of successful farming, yet it is often overlooked. Soil scientist Hamond Motsi shares expert insights into soil sampling – an essential practice that can significantly improve crop yields and quality.

Motsi, a PhD candidate in soil science at Stellenbosch University, delves into the intricacies of soil sampling and its role in sustainable agriculture.

“Soil sampling during farming is a continuous process,” Motsi notes.

While samples can be collected at any time, certain periods are particularly significant:

Before planting: Establishes the soil’s readiness for cultivation.
After harvest: Assesses how the previous crop cycle impacted soil health.
During crop growth: Provides insights at different growth stages, such as after germination or during flowering.

Key indicators from soil analysis reports

Motsi says farmers should focus on the following aspects when reviewing soil analysis reports:

Nutrients: Look at primary nutrients (nitrogen, phosphorus, potassium) and secondary ones (calcium, magnesium, sulphur). Do not neglect micronutrients like zinc and copper, which play critical roles in plant development.
pH levels: Ideal ranges depend on the crop but typically fall between 6 and 8. Farmers must address pH imbalances to optimise growth.
Salinity: Excessive salt accumulation can harm crops and must be managed through proper agronomic practices.
Degradation indicators: Include erosion, infertility, salinity, and acidity, all of which reduce soil’s capacity to support crops.

“Degradation can be defined as anything that can reduce the status of the soil to support the plants,” explains Motsi.

Motsi shares that accurate soil sampling requires proper techniques and tools:

Tools: An auger is the preferred tool, but a hoe can also suffice.
Depth: Samples should typically be collected from 0–30 cm, where most root activity occurs.
Field variation: Variations in topography (e.g., slopes) can affect results. Motsi advises sampling these areas separately to gain precise insights.

“It’s not something which farmers can undertake from the beginning because it needs a certain degree of technical know-how,” he says. He encourages farmers to consult with agricultural extension officers, laboratories, or the department of agriculture for guidance.