By Bryan Griffiths and Fiona Burnett SRUC, for the Farm Advisory Service

Soil health – why and how?

Interest in soil health is growing at all levels. It is a key area for policy with the UK government’s 25-year environment plan, launched earlier this year, indicating that future agricultural policy will focus on soil health and structure.

Targets on soil health got further mention when the Agricultural Bill, was set out last week. The testing of soils in relation to reducing agricultural greenhouse gas emissions is also under consideration. The benefits of improving soil health by integrating the biology, physics and chemistry will pay dividends in maximising efficiency and yields whilst potentially reducing pollution, erosion, irrigation, fertiliser and tillage costs.

Soil health can seem a complex business so what are the key features of a healthy soil, and the benefits of testing and how do you set about improving it?

Soil health is not just about having a good biological system (lots of worms, ample beneficial microbes to keep the pathogens in check) there are also physical and chemical aspects, and to have soil in ‘good heart’ you need the biology (biodiversity), physics and chemistry in balance.

Basic nutrient testing is one aspect, as are simple indicators of good physical structure as in the widely used Visual Estimation of Soil Structure (VESS) test which is a straightforward, quick soil test using a spade to assess topsoil. Incorporating biological measures of soil health with the physical and chemical properties of a soil to give a single unified test might seem a daunting prospect, but there are a small number of indicators that can give you a good measure of soil health.

In Scotland, the new SAC Soil Health Test measures soil organic matter, soil physical structure, earthworms and potentially mineralisable nitrogen, as well pH and nutrients (P, K, Mg). These results are presented in an easy to understand ‘traffic-light’ format, giving a simple overview of soil health, together with detailed descriptions and information on each of the factors.

Any test of soil health however, is simply a snapshot of the status of your field. Large additional benefits are gained by comparing results over time and comparing results between fields. Comparing fields under similar conditions lets you consider how good your soils really are and what you can expect from them. Repeated sampling of the same field between seasons will let you see how your soils are changing over time and will be useful in testing what the effect of your management practices has been.

As well as providing management advice and soil health benchmarking, such as regional comparisons, repeated sampling and data collection enables long-term analysis of the effects of management changes on soil quality.

Good soil health is important in the here and now for good and sustainable crop growth but may well be increasingly a feature of post-Brexit greening measures.

* Soil health is at the forefront of the knowledge trials at the Tillage-Live event taking place on Wednesday, September 26, 2018 at Dunbar, East Lothian.