The importance of soil sampling

FarmBiz|June 2020

The importance of soil sampling
During a visit to the Agricultural Research Council’s (ARC) Vegetable and Ornamental Plants campus at Roodeplaat, Farmbiz caught up with Michael Kidson, a soil scientist at the Institute for Soil, Climate and Water (ISCW).
Ursula Human

He spoke to Ursula Human about the value of and processes involved in soil sampling.

Michael is an expert in edaphology, one of the two main branches of soil science. which focuses on studying the functioning of soil as part of an ecosystem. The other branch is pedology, or the classification of soils. During the visit he not only demonstrated how to take soil samples, but also explained why this is important for farmers.

Why take soil samples?

According to Michael, the process of soil sampling gives you a very good idea of the chemical composition of the soil on your farm. This is necessary to get accurate advice about the correct type and quantity of fertiliser to apply for optimum production.

A soil particle analysis will also give you information regarding the texture composition of your soil. This refers to the size ratio of soil particles to determine the texture class of soil, i.e. clay, sand or loam, and will guide you on how well the soil retains moisture and how well roots will develop in the soil.

Michael emphasises that a large percentage of soil in South Africa is not suited for cultivation and should rather be used for pasture. An example of soil unsuitable for cultivation is Mispah soil, which has shallow topsoil directly on top of a layer of rock.

How to take soil samples

Topsoil usually makes up the first 15 to 25cm of soil and contains the most organic matter and micro-organisms. This is the part of the soil where most biological soil activity occurs.


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June 2020