Soil Nutrition and Testing

Soil Testing and Nutrition

Soil sampling is used as a crop management tool that can provide you with an early warning that potential problems may be looming on your future crop.

A soil test is to assess the current nutrient levels in the soil. The standard test (ST01) will measure the plant available content of phosphorus, potassium, calcium, magnesium, sodium and sulphur, soil pH, humus matter and exchangeable acidity and advance test (ST02) will also include zinc, copper, manganese, iron and boron.

These analyses indicate whether to apply lime (Type of lime and how much) or sulphur to change pH. Correct interpreting of analytical results will give you your fertilizer recommendations based on those results.

Soil Sampling

Soil testing is often last on the priority list for most growers and often sample collection is done haphazardly by a clerk or a foreman not really familiar with the correct way to collect soil samples. How you take your samples determines the accuracy of your soil test. To avoid costly over and under fertilization errors, take time to collect soil samples representative of the land. Reace from Maguires can assist you with sampling if he is in your area.

Soil testing should be done early (at least 6 months prior to planting) to allow yourselves adequate time for the lime and sulphur to react with the soil when remediating pH levels.

Soil pH determination is more reliable when the soil is moist. The more subsamples taken from your land the better but in general take 5 to 10 subsamples for each sample. Mix subsamples well in a bucket before taking approximately 350g of the mixture as your sample. Most crop roots are in the top 30cms of soil so take your subsamples to a depth of 30cms.

Maguires will be offering a service of sending your soil sample to NviroTek Soil Sampling Laboratories in South Africa. They are internationally accredited by SANAS (South African National Accreditation System) in line with requirements of the ISO/IEC 17025:2005 and ISO/IEC 17025:2017 standards


Soil sample bags for shipment to S.A are available from Maguires for collecting your soil samples


Sean Price

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