The SWARM Hub has collated and analysed the data from 3,447 anonymised soil samples collected during the Soils for Profit (S4P) programme to produce a full soils analysis report in association with S4P staff. The current cropping for each field sampled was recorded and each soil sample was analysed for pH, SOM (soil organic matter), and key nutrients P, K and Mg.
The crop types have been divided into arable (including cereals, vegetables and bulbs) and grassland (including permanent pasture, short-term leys and silage crops)*.
The optimum pH range, SOM benchmark and target key nutrient indices were taken from RB209 Fertiliser Manual, Defra 2010 (now superceded by the new version released in 2017).
This report need to be read in context as it is anticipated that many of the soil samples were taken from poorly performing fields. However, the results are still quite staggering.
- 47% of all samples were below the target pH range
- 31.8% of arable soil samples were below the target pH range of 6.2 – 6.4**
- 51.6% of grassland samples were below the target pH range 6.0 – 6.2**
** as recommended in RB209 Fertiliser Manual, Defra 2010
Any soil samples below the recommended pH will significantly reduce the availability of nutrients to the crop, especially in the case of phosphate.
Click on the graphs below to see the proportion of arable or grassland soil samples that were outside the optimum pH per county.
Soil organic matter (SOM)
SOM is a crucial part of soil biology. It is simply any material which was once part of a living organism or produced by one. It occurs naturally in soils and comes from decomposing animals, plant roots and crop residues. More organic matter can be added to soil from various sources including animal manures, composts and alternative wastes. SOM is influenced by factors such as soil type, climate and farming systems.
This analysis found that unsurprisingly more arable soil samples were below the recommended 3% benchmark:
- 11.3% of soil samples from arable fields had SOM below 3%
- 1.5% of grassland soil samples had SOM below 3%
Click on the graphs below to see how many soil samples from fields in the South West were below the advised 3% threshold.
Soil key nutrients P and K
Phosphate (P) and Potash (K) are essential elements for crop growth and being below the target indices will impact on crop productivity. Click on the 4 graphs below to see how many samples (per county) were below, within and above the target indices for each key nutrient.
To read the full report please click here. (LINK)