Where and how often do I do each test?

If it’s your first time soil sampling, start by choosing one sample site in each field you have added as an indicator site to monitor progress. Unsure of what we mean by ‘soil sample’? Read our guide – What is a Soilmentor Sample?.

If you want to monitor a field’s soil health more accurately, you can add more sample sites within a field for soil testing, for example at:

  1. The best performing spot in the field
  2. The worst performing spot in the field
  3. An ‘average’ spot in the field

You can create as many samples as you like – it’s all about how much time you are able to dedicate to soil testing!

How do I do the tests in each field?

  1. Spade and Probe Tests

For spade tests, you should dig out a 20cm x 20cm block, digging the spade down on three sides and levering out the soil block with your spade from the dug side opposite to the undisturbed side.

Try to keep the soil block as intact as possible.

Put the soil block on a tray or bag, and if there is any left in the pit going down to 20cm dig this out and put it on the tray too.

Use the undisturbed side to do your VESS top/bottom depth assessment – don’t forget to add a photo to Soilmentor!.

2. Grass Tests

Grass tests, such as plate meter & sward stick readings, should be done a minimum of six times in each field, along a ‘W walk’ (instructions for this method in the green box below). For large fields, take at least one grass test reading per acre along your W walk.

In Soilmentor, record information for each grass test you take under one ‘sample site‘ – you can a create a sample for all of your grass test readings in each field called ‘W Walk’, or add your recordings to an existing sample.

3. Lab Tests: Taking a “Compound” Sample

As well as observational, ground cover & grass tests, you can add your lab results to Soilmentor, too.

To take a lab soil sample you want to get a sense of an average for the soil in that field.

Taking samples to combine into a compound sample across your W walk is one way to get a representative average for a whole field.

  1. Walk a W across the field (instructions below)
  2. Take 20-25 “sub samples” more or less evenly along the way
  3. Mix sub-samples well in a bag
  4. Close bag
  5. Label bag with field name

Avoid field margins, hedges and soil under water troughs – anywhere where your results are likely to be unrepresentative of the field.

What is a ‘W Walk’?

For some tests, it may be useful to ‘walk a W’, where you need to do multiple recordings across the field, such as for taking Plate Meter or Sward Stick readings.

To do a W Walk, you should start in the corner of your chosen field, and walk about 20 steps away from the corner towards the middle of the field. This is the start of your W.

Turn around and walk back to continue your ‘W’ shape, zigzagging through the field to cover a good amount of your field’s variability.

Try to remain 20 steps away from the edge of your field as you walk, taking readings as you go.

Once you’ve finished your W walk, you should be in another corner of your field, having completed 3 turns of your zigzag!