By Gavin Elrick,

Senior consultant with SRUC

With the current focus on maintaining good soil health and productivity for the future, and with political hints being given that future subsidies will be linked to environmental benefits and public goods, it is essential that soil condition is maintained or improved.

Soil health is a complex interaction of physics, chemistry and biology which all require being at optimum levels for the soil to perform its main function as the growth medium for the crop. At Tillage Live, SAC Consulting, part of Scotland’s Rural College (SRUC), will be launching its Soil Health Test or ‘MOT’ service, building on routine testing for pH and nutrients (P, K, Mg, Ca, Na) already delivered by SAC Consulting.

The ‘soil MOT’ also measures soil organic matter, soil physical structure, earthworms and potentially mineralisable nitrogen.

The 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. The system’s main benefit is that it utilises methods developed for the specific requirements of Scottish soils and takes into account the issues that they face compared to the rest of the UK.

One of the issues that will be highlighted is the management of soil phosphorus on different soil types throughout Scotland (more information on this can be found on the Farm Advisory Service (FAS) website: https://www.fas.scot/?p=10437)

As well as providing management advice and soil health benchmarking, SAC Consulting’s repeated sampling and data collection enables long-term analysis of the effects of management changes on soil quality. Professor Bryan Griffiths, chair in soil ecology at the SRUC Crop and Soil Systems Research Group, and other local SAC consultants will be on hand throughout Tillage Live to discuss the Soil Health Test and research going on in this area.

The other main issues which will be discussed will be soil compaction, soil structure and soil drainage. These issues are all too easily forgotten after the dry summer we have just experienced, but it is less than a year since we suffered one of Scotland’s wettest growing seasons, where the soil suffered compaction and structural damage.

The current good soil conditions are an opportunity to deal with drainage problems identified during the previous season.

Good drainage provides a wide range of benefits for farm efficiency:

• Improved crop growth and yields. For example, in a poor year, the undrained land will have reduced yield and in some cases it may be a total crop failure;

• Better nutrient availability and uptake. For example, due to deeper root system and less nitrogen lost to the environment;

• Crops are less prone to disease;

• Drier soils are warmer, which increases the growing season and brings forward sowing and harvest dates;

• Better drained soils are more resistant to drought due to deeper root systems;

• Well drained soils save fuel as they are easier to cultivate;

• Less damage to the soil structure as drier soils are more resistant to pressure;

• Well drained soils have more available work days and recover more quickly after heavy rain;

• Better animal health due to reduced risk of waterborne disease and parasites, such as liver fluke;

• Less poaching of soil surface due to livestock;

• And, there’s a longer grazing season.

Optimum farm efficiency, whether it is arable or livestock based, relies on good soil drainage to maximise productivity. Wetter soils are also prone to higher losses of nitrous oxide – a powerful greenhouse gas which is 300 times more potent than carbon dioxide.

Land drainage is affected by a number of problems both natural and manmade but can be divided into three main types:

• Surface water problems

• Ground water problems

• Springs and seepage lines

In addition, there are specialist drainage problems, such as iron ochre and running sand, which can occur in the above situations and require different solutions compared to standard drainage.

In order for any drainage system to remove excess soil water, it is essential that the soil structure above the drains is open and not compacted and, at Tillage Live, myself and senior consultant, Seamus Donnelly, will be in a soil pit looking at compaction, soil structure, rooting depth, drainage issues and will discuss solutions such as tillage and green cover crops.

The soil structure can be improved by a number of natural processes, including activity of roots and soil organisms, especially earthworms; wetting and drying; and freezing and thawing.

The dry summer we have just experienced will have provided a natural sub-soiling effect, allowing roots to penetrate deeper to access water which in turn will open up the soil, allowing the soil fauna to assist in soil structural improvement.

An essential component for the soil fauna to work well is the organic matter levels in the soil. Amendments of organic matter from green compost, farmyard manures and green crop manures can all assist in improving the soil biology and the soils resilience to compaction damage.

Examples of EFA cover crops and information on green manures will be on the SRUC/SAC Consulting stand along with consultants available to discuss the benefits for different cropping situations.

We look forward to seeing you at Tillage Live.