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Plantwise Factsheets for Farmers

How to take a soil sample for analysis


Recognize the problem

Farmers experience deficiencies of nutrients such as phosphorous, calcium, magnesium and other deficiencies in their fields which reduce plant growth and yield. To address these deficiencies, professional soil testing is required to understand which soil nutrients are present at what quantities in the soils and which ones are not enough for plant growth. However, many farmers do not know how to collect and send the soil samples required for soil testing.


Soils vary in shape, colour, texture, particle size and nutrients. This means that the soil contents are different from field to field. To understand which nutrients are in the soil or not, a soil sample has to be collected, and sent to a laboratory. Tests will determine the amount of nutrients, pH levels (acidity or alkalinity) and organic matter in the field. The best soil samples are collected before rains or after harvest of previous crop because too much water affects soil pH and may wash away some nutrients. The soil test results help us know what type of fertiliser to apply to have healthy plants. With the right fertilizers at the right amount, yields can enormously increase.


  • Mark the field either in a rectangular or square shape, covering the whole area of interest.
  • Using a soil auger or spade, dig out soil from about 10-20cm deep along the diagonal line of the field (tools must be clean to avoid contamination)
  • Collect these samples from one corner of the field towards the other
  • Place samples into a plastic bucket or on clear ground and mix thoroughly
  • Do not use iron buckets or grassy or leafy ground to avoid contamination
  • Collect 1kg (2 handfuls) of the mixed soils and place in a plastic bag
  • Label the plastic bag with name of farmer, name of the farm, location and date for easy identification, and request pH and nutrient tests.
  • Send this sample for testing either to mount Makulu in Chilanga, University of Zambia in Lusaka or Mwekera Research Station in Kitwe
  • Once test results are collected and interpreted, the farmers can now apply fertilizers or lime or other nutrients based on the test results
  • A soil test result will show amounts of the following: N = nitrogen, P = phosphorous, K = potassium, Ca = calcium, lime for adding calcium, pH<7 is acid  and pH>7 is alkaline, Org= organic matter

The recommendations in this factsheet are relevant to: Zambia

Authors: Donald Mwaba, Musenga Chella
Department of Agriculture, Ministry of Agriculture
tel: +260977418738 email:
©CAB International. Published under a CC-BY-SA 4.0 licence.

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