How to...
How
to ...
take soil samples
A step by step guide to the sampling procedure for soil analysis
- by Isobel van der Stoep and Mike de Villiers
T
he analysis of soil samples is a very important tool to the both the irrigation designer and the
producer, who has to schedule the correct application of water, fertilisers and corrective measures to
the soil in order to optimise both crop yields and the efficient use of water. This editorial will focus
on the objectives and soil sampling processes.
INTRODUCTION
Soil sampling appears to be an extremely simple process,
however the samples form the basis of a very important process
known as a Soil Analysis. The results of the analysis will provide
critical information to the irrigation design team in terms of soil
preparation, irrigation scheduling and field management. It is,
therefore, unnecessary to stress how important the sampling
procedure is to the outcome of the analysis.
The location, depth and handling of samples once taken should
be done according to a clearly defined plan in conjunction with
the Analytical Laboratory and the Irrigation Design Team.
Sampling should be an on-going procedure throughout the
life of an irrigated field, from soil preparation to maintenance
monitoring, in order to apply corrective measures to the
achievement of healthy and productive crops.
The objectives of soil analysis are as follows:
• Planning of irrigation and fertilisation systems
• Irrigation scheduling, relating to the calibration of probes
and tensiometers
• The classification of soils relating to the application of
fertilisers and lime
• To evaluate soil fertility
• To detect and correct imbalances in nutrient concentrations
• To assist with the determination of accurate cultivation/
management units.
The most important advantage of on-going soil analysis is the
ability to monitor changes in soil fertility in order to apply corrective
action before nutritional stress occurs. Specialist analytical
laboratories, have developed specific norms and procedures to
assist with the interpretation of sampling
Acknowledgements:
We would like to thank the following persons for their assistance with this article Prof. Martin Steyn, Department of Plant and Soil sciences, University of Pretoria
Randy Kumasamba, Department of Plant and Soil sciences, University of Pretoria
Tielman Roos, Limpopo Department of Agriculture
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SABI | JUNE/JULY 2016