New year resolutions are seldom kept beyond Burns Night and normally involve giving up something that you like. So how about one for 2020 that will commit you to taking soil samples in January? Putting in place a coherent soil management plan is key to improving the productivity of your soils, and without the knowledge gained from a soil test this cannot be done.
A simple testing protocol should include:
1) Retesting is done every 3 or 4 years; this initially should include the soil textural classification of the soil. This will show the size of the clay, silt and sand fractions.
2) Testing is done between October and February at least two months after any fertiliser or FYM applications.
3) That the same laboratory is used every time, as it avoids any issue of differences in lab protocols.
4) Samples should be taken uniformly across the soil profile to 15 cm in depth.
5) Results for P, K and Mg are reported on a Mg / litre basis and not simply as indices.
6) Measure the soil carbon. This can be calculated from measuring the Soil Organic Matter (SOM) as calculated by loss on Ignition. Soil Carbon is then calculated as being 58% of the soil organic matter.
Armed with the percentage clay in a sample and the SOM, it is possible to determine how healthy the soil is. Soil quality can be assessed by the ratio of clay to soil carbon with a ratio of below 8 being ideal and above 15 as being degraded. For arable soils a figure of 10 seems sensible. The advantage of this as a measure, is that its takes into consideration the clay content and it’s the clay component that helps to hold the carbon in the soil.
For all your soil and fertiliser questions contact William at firstname.lastname@example.org or your local FCG FACTS qualified consultant.