How do I Know Where to do Each Test?
Walk to one corner of your field, walk 20 steps away from the corner towards the middle of the field.
This is the start of your W.
Don’t get closer than 20 steps from the edge of your field.
Aim for the other end of the W to be in a similar spot in the other corner of the field either to your right or left.
How Many Times do I Need to do Each Test in a Field?
The Codes for the tests correspond to 3 different types of test: 1 – Spade tests, 2 – Grass tests and 3- Probe tests.
Below are recommendations for the optimal number of samples you would take for each test type in a field as well as a tiered system that you can adopt based on what’s possible for you.
Please note the tiers require increasing amounts of time but also will most likely result in more accurate data.
The most important thing is that you do the tests in a similar manner in each field and repeat them over the year(s).
Aim for a minimum of 3 spade/probe tests in each field and 6 grass tests.
Do the spade/probe tests 3-5 times across the W. If all the readings are approximately the same, then you can assume the field is more or less uniform on average and those readings are representative. If not then continue taking readings until you do get more repetitive readings.
For grass tests do as many as you can across the W in a set amount of time you have allotted yourself. Once you get going we reckon you can do 15 grass tests in 40 minutes, including the time it takes to walk from one sample spot to the next.
Do 1 spade/probe tests per 8 acres and 1 grass test per acre, equally spaced across the W. As outlined below.
Optimal Guidelines for frequency of tests
1 set of spade tests per 8 acres. Equally spaced across W.
Insert spade about 20cm down. Dig out spade-full of ground, intact as possible.
One set per acre. Equally spaced across W.
Once you reach a sample spot, throw the Quadrat a few metres in front of you and to tests at that spot to avoid any bias of which spot you choose to look at.
1 set of soil tests per 8 acres. Equally spaced across W.
For Lab Tests: Take a “Compound” Sample
In the app there is the option to add in lab test readings as well, as it can be interesting to compare to these as well. In order to take a lab soil sample you want to create an average for the soils in that field.
The W is a way to create a representative average for a whole field.
Avoid: Field margins, hedges, water troughs etc
- Walk a W across the field
- Take 20-25 “sub samples” more or less evenly along the way
- Mix sub-samples well in a bag
- Close bag
- Label bag with field name