Carrying on from ‘Lawn assessment – part 1’:
I’ve just looked at some of the visual assessments you can easily carry out on a lawn, so let’s just look below the surface.
Take a core of soil out – use either a narrow soil corer, or failing that you can just use a trowel to scoop out some of the topsoil or cut a slice out using a penknife.
Take out some cores so you can see what the root system is like, plus if there is a thatch layer present, or not. You can then collect some of the extracted soil and carry out a hand texturing test to give an indication of the type of soil you have.
I’d like to see a minimum root depth of at least 50mm, which would be a good minimum depth, but ideally this would be extended to 100mm or more. The picture above shows the core starting to break at around the 35mm (with a sneaky little earthworm having a peak out of the core), so the roots are only holding together less than what I would consider a minimum requirement. There isn’t any thatch layer present – perennial ryegrass isn’t a particularly thatch forming grass, plus with the soil pH being only slightly acidic and with the activity of the earthworms and micro-organisms any potential build up of undesirable thatch is readily broken down.
What’s the soil type? Free draining sandy soil, or heavier clay soil, or something in between. Well, a simple hand textural analysis can provide a lot of valuable information.
Track down a suitable chart to follow – I used the one in my copy of Soil Science: Methods & Applications (Rowell, D.L. 1994).
By following the key it indicated that the soil is a Clay Loam. The process consisted of collecting some soil, wetting it, rolling it into ball, then I made a narrow ribbon out of it, bending it into a U bend and then making a ring. Simple and it only takes about 5-minutes. Just make sure you wash your hands afterwards.
I also collected some environmental data – the air temperature (8.9C) and the soil temperature at 50mm depth (7.2C), as well as the light level in LUX. I used a simple environmental meter to capture this – it will also measure relative humidity and sound. The light level reading was 9,570 LUX at the time the photograph was taken but was constantly fluctuating up and down, maybe reaching 10,500 LUX. This is a typical reading for daylight without sun, which it was. See Wikipedia > Lux for some background reading.
What else could I have assessed. Well, I could have carried out a nutrient test for phosphorus (P) and potassium (K) to see if there was a deficiency in either of these macro-nutrients. A complete N:P:K fertiliser for my spring application will, I suspect, be more than adequate to help develop a strong, healthy sward.
I just need to work out my schedule of works for my spring lawn renovation, and cost it up. The first thing I will be able to start on is the hand forking as this will take a bit of time and effort to cover the entire lawn. More on this soon.
Chris Gray, 17th March 2017 (updated 25th March)