The Hutton Institute in Scotland is a research facility that aims to drive the sustainable use of land and natural resources. It is presently involved in research into soil improvement for growers in Scotland and has made available two free apps for the iPhone that anyone can use whether on the scale of a large farm or a garden. I am interested in learning more about soil, particularly in our Strathkinness Community Garden, so we can understand how our use of compost, comfrey, and other soil improvers affects plant growth. I share my experience using the apps below, in hope of inspiring others to do likewise.
Soil Information For Scottish Soils (SIFSS)
SIFSS app allows you to choose the location of your garden from the map of Scotland where you are given general information on your soil type, then you can choose more specific information from from a menu, such as pH, carbon, nitrogen and many more. The soil in our village Community Garden is listed as Caprington series, sandy clay loam derived from Carboniferous shales, moderately well drained, coloured dulling with orange flecks in the subsoil, moderately stony with a potential rooting depth of 40 to 50 cm. Similar soils are found in Ayrshire, Stirling and the East Neuk of Fife.
Specific information is as follows:
- Carbon 2.5% at 25cm. depth
- Nitrogen 0.25% at 10 cm. depth
- pH 6 to 6.5 at all depths from 10 to 80 cm
- Base saturation 77% at 14 cm. and 81% at 40 cm
- Clay 20%
- Silt 25%
- Sand 55%
The part of this general information I can use is the pH which shows an acidic soil indicating that some ground limestone/ Dolomitic limestone could be added to the soil when growing brassicas and legumes. The measured pH in our Community Garden is in fact slightly higher at 6.7. Carbon at 2.5% is typical for non organic farmland in this area and is a characteristic of the farming methods used.
Soil Organic Carbon Information (SOCI)
I used SOCI app to measure the organic content and carbon content present in the three types of soil I spoke about in the PLANT workshop on Soil testing and improvement in June. This app only applies to Scottish locations and you will need to request a colour correction card that will be posted to you. The instructions thereafter are simple and require you to dig a hole, position the card (I chose a depth of 25 cm as no depth was specified). I found it important to get a magnified image in dull conditions as a smaller image in sunshine did not work. The photo above is from the 200 year old garden soil in my cottage that I referred to in the workshop video. You will see from the settlement tests in the video that the soil is very dark from two centuries of cultivation. The results for tests on this soil and in two locations of the Community Garden are as follows:
- Cottage soil. organic matter 9.6% carbon 5.6 %
- Community Garden allotment. organic matter 9.9% carbon 5.7%
- Community Garden orchard. Organic matter 6.4% carbon 3.7%
All the soil carbon is greater than the 2.5% typical agricultural soil listed for Strathkinness in the SIFSS app. The allotment carbon has been built up in the last ten years by adding compost, manure, and comfrey with only shallow cultivation. However it’s interesting that high levels of the organic matter/ carbon are found at a depth of 25 cm. The orchard is not fed so much and has lower levels of carbon. The 200 year old garden soil is only lightly fed with compost as it grows cottage garden flowers and is not dug deeply. It still has high levels of carbon which were probably built up over the years.
I intend to use the information by continuing to encourage others who grow crops in our Community Garden to use these organic materials to improve their soil and use the cultivation recommendations supplied in the video such as no dig/shallow cultivation, crop rotation, close crop spacing, catch cropping, and green manures.
There is also a lot of discussion presently regarding soil sequestration of CO2 using some of the methods mentioned above in mitigating Climate Change. The article ‘Can Soil Help Combat Climate Change’ gives a good summary of this, introducing the concept of ‘fast pool carbon’ that is easily released back into the atmosphere as CO2 and ‘slow pool carbon’ which is very stable and can remain in the soil for many years.
I intend to keep in touch with this work as I believe that even on the small scale that we operate on, every little can help.