Soil strategy answers key farming sustainability questions

How can I reduce tillage without adding to my risk?  What are the best ways of cutting my vulnerability to the weather? How much carbon can I realistically capture?

What do I need to do to achieve the most rewarding SFI soil standards? Where should I focus my improvement efforts for the greatest overall value?

These are just a few of the practical questions the Green Horizons Soil Resilience Strategy launched this spring by national agronomy leader, Agrii is designed to answer. Its aim is to help growers across the country improve the resilience of their soils and sustainability of thier systems.

© Agrii

Developed following studies with the UK Centre for Ecology & Hydrology (UKCEH) and others, the strategy pulls together the latest understanding of soil structure, chemistry and biology.

It provides a carefully structured approach to improving soil resilience based on the best available science, a thorough understanding of soil management, and sound practical advice and action.

Flexible packages of laboratory and field-based assessments are designed to suit every soil condition, farming system and farm need, with a team of soil management advisers providing specialist support.

“Our strategy employs a range of modern lab tests and hands-on, in-field appraisals to identify the current health of farmed soils,” explained Agrii sustainability manager, Amy Watkins at the launch.

“Together with a good understanding of each farm’s particular objectives, needs and resources and practical soil management intelligence, these enable us to work with growers to develop the most appropriate plans of progressive improvement action.

“As well as concentrating the attention on some of the best areas for and ways of improving both immediate farm productivity and long-term sustainability, our strategy provides an ideal foundation for making the most of the evolving SFI soil standards payments.”

Provided through the national networks of Agrii agronomists and RHIZA specialists, the Agrii Soil Resilience Strategy (SRS) starts with a thorough soil health assessment involving broad spectrum laboratory nutrient, pH and organic matter testing. More detailed measurements of soil carbon at different depths can also be added.

Alongside this it offers a suite of in-field soil biology, structure and water management assessments, employing standardised methodologies for worm activity monitoring, Visual Evaluation of Soil Structure (VESS), penetrometer, slake, aggregate stability and infiltration testing.

Carried out on a sample of fields representative of the farm as a whole or those posing particular management concerns – depending on individual preferences – the results of all these assessments are set out in easy-to-understand reports.

“Our lab and field assessments produce a raft of benchmarking data, but the real value of what we offer is in the practical action plans we develop from them rather than what they actually show,” says senior Agrii agronomist, Andrew Richards, who has played a leading role in the SRS development.

“Only by combining a detailed understanding of each grower’s resources and objectives with the best intelligence on all aspects of soil health and its management can we translate our assessments into the most appropriate improvement action.

“More fundamental soil health constraints like pH, for instance, need to be addressed before it’s worth you doing much else. Equally, moving to direct drilling without making sure your ground is ready for it could easily jeopardise performance. And it is essential to target levels of organic matter improvement that are realistic for both your soils and farming system.

“Amongst other things, our work with UKCEH has shown the clay:carbon ratio of soils is a much more useful measure of their resilience than organic matter alone,” he points out.

“Because clay particles bind organic matter, the greater the clay content of a soil the more organic carbon it can store, but the higher the level it will require to be resilient and the slower it will be to build.

“So, we have made this metric central to our approach. Only by establishing exactly where soils sit on the clay:carbon resilience scale developed from Rothamsted work with the national soil survey, can we provide the most practical recommendations for both soil health and soil carbon storage improvements.”

The Agrii team accepts that much remains to be fully understood about soil biology, the best ways of measuring it, and its complex interactions with soil structure and chemistry.

So, their approach has been designed for the greatest flexibility in responding to future advances in the science as well as in meeting the individual needs of different growers and systems, not to mention changing legislation and agricultural support.

Appreciating there is no ideal soil biological community, it sets out to assess the most practical indicators of all-round soil health and productivity available as benchmarks for planning and monitoring improvements over time.

Extensive work in trialling and on-farm testing over several years have identified a whole host of critical considerations in both the assessments and their use. These include:

• Selecting fields carefully on the basis of individual grower needs;
• Taking samples that are as representative as possible of field status;
• Making biological assessments at the best time, preferably in the spring;
• Recording the weather at the time of each assessment;
• Basing all organic matter testing on the same proven process (preferably DUMAS);
• Adjusting for bulk density, chalk and stone content for accurate carbon accounting;
• Following-up in-depth initial assessments with seasonal snapshots;
• Re-testing every 3-5 years – ideally with active carbon monitoring in between;
• Making future assessments at the same time of the year and under similar conditions;
• Knowing the cultivation and cropping history of the fields assessed; and,
• Understanding the particular objectives and constraints of the farm.

“Capturing the detail of all our assessments in the standard field reports we have developed to present the results in the clearest and most practical way provides the best basis for benchmarking and improvement planning,” says Amy Watkins.

“Our reports give an objective and scientifically-valid record of soil status, allowing individual farm teams to set realistic objectives for improvement; monitor their success in meeting them; and (increasingly importantly for the future) demonstrate their progress to others – be they customers, carbon off-setters, agricultural support providers or the general public.”

“To encourage the widest possible participation, we have kept SRS charges at our standard consultancy and laboratory rates as reasonable as we can,” she stresses. “The individual cost will, of course, depend on the specific assessments selected, the number of fields included and the frequency of re-testing.”

Download the Agrii Soil Resilience Strategy brochure