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The Hidden Value of Soil Organic Matter

Soil organic matter is key to healthy soil – it provides a nutrient source, aids soil water holding capacity, helps to improve soil structure and reduces erosion risk.  However, once you lose it, soil organic matter can take many years to replace.

Soil organic matter, a mix of decomposing roots, crop residues and manures, helps to avoid problems such as compaction and increased run-off, which can result in a loss of both soil and valuable nutrients off the farm.  Soils with poor structure are more difficult to work and often need more power and effort to resolve the problem, costing you both fuel and time.  These issues can present a financial loss to the business, reduce efficiency and increase the farm carbon footprint.

So how can we keep hold of and improve levels of soil organic matter?  The first step would be to know what you have – this can be easily included in a routine soil test.  Organic matter content in Scottish soils ranges depending on soil texture and climate, so it’s worth a look at the Scottish Soils website which contains information to help understand your soil.

To boost organic matter in your soil, there are a number of options to consider:

  • Reduced tillage systems
  • If feasible, chop and spread straw rather than baling and removing
  • Include species-diverse leys into the arable rotation
  • Grow cover crops and green manures which can be cut and mulched as well as grown for forage
  • Consider winter cover crops. Cover crops also have the benefit of capturing nutrients at a time of year when ground might be bare and nutrients would otherwise be lost from the farm.
  • Consider compost – either buying in or making your own (from woodchip, straw, farmyard manure, hen pen)

Although not a quick job, improving and maintaining soil organic matter levels will be beneficial for your farm in the long run, both in terms of crop yields, improving efficiency and benefitting soil health.

Rebecca Audsley, Climate Change Manager, SAC Consulting

This article from Farming for a Better Climate was funded by the Scottish Government as part of Scotland’s Farm Advisory Service and first published in the Farming Scotland Magazine during September 2019.