Friday, 12 November 2021
AHDB Strategic Cereal Farm Scotland uses cover crops to help provide living roots in soils all year round. It is part of an effort to improve soil fertility and resilience, with the strategy monitored with a Soil Health Scorecard.
Cover crop approach
Speaking at an AHDB/SRUC soil health technical workshop at Balbirnie Home Farms in Fife earlier this month, David Aglen, Farms Manager, said: “Cover crops are starting to drive our system. As they harvest sunshine, I liken them to solar panels. By keeping something growing, our panels work all year round, pumping energy into the soil. This keeps the soil biology thriving, albeit at a slightly slower pace in the winter. Then, come spring, when it warms up, it is all ready to go. In contrast, a bare stubble field has all that biology sitting there, hungry.”
Cover crops are drilled as quickly as possible after harvest, which can be quite late in the season. Because of this, David has found that the cover crops that perform well on his farm are large-seeded crops.
He said: “Crops with large seeds produce plants with a bit more vigour, which actually get up and do some good. We use winter peas, initially imported from Europe, which we have multiplied to keep the costs down, rye in front of broad-leaved crops and vegetables, as well as beans, as cover crops. We are lucky that we can feed cover crops to the livestock, drill through them in the spring and leave them as a mulch. This allows us to keep the soil biology alive.”
Soil health principles
Speaking at the event, Christine Watson, Professor of Agricultural Systems at SRUC, said: “There are some general principles on how to manage soils and improve soil health – such as increasing organic matter inputs, widening the rotation and diversity, adopting the use of cover crops, reducing tillage and introducing livestock.
“Whether it’s a grass cropping mixture or a cover cropping mixture, a more diverse rotation is going to bring benefits in terms of habitat diversity, both above and below ground. Plants are as diverse below the ground as they are above it.”
Entering the second year as host of Strategic Cereal Farm Scotland, David explained that the first year was mostly spent baselining and that involved a health check for soils.
He said: “The most important thing we’ve learnt from our soil baselining studies has been that we need to pay attention to soil compaction, we are seeing pans creeping in here and there. This has reinforced our aim to keep a living root in the soil all the time.
“This year, all our harvested fields have either the following cash crop or a green cover crop in them. This should help reduce the impact of rain on the soil surface and may lessen the ponding, which occurs in one or two fields over winter, because of a very small pan that forms on the surface with rainfall. We are also now direct drilling as much as we can to minimise soil movement and we monitor our soils annually.”
Soil health scorecard
All soils are different and there is no one-size-fits-all tool for management. However, soil health reviews can be used to monitor the impact of management interventions.
Dr Amanda Bennett, an AHDB environmental scientist, who leads on the Soil Biology and Soil Health Partnership, said: “An integrated approach is needed to measure soil health. This requires chemical, physical and biological assessments. Within the AHDB/BBRO-funded partnership, we have developed a robust set of soil health indicators and tested them on farm since 2017.”
The result is the Soil Health Scorecard, which uses key indicators and provides information on the condition of the soil. It combines physical observations of topsoil and earthworm counts in the field, with the results from analysis of soil samples sent for laboratory testing for pH, nutrients and soil organic matter, all done at the same time from the same 20 cm x 20 cm block of soil, dug with a spade.
Amanda said: “For routine soil health monitoring, sampling should take place once per rotation and at the same time of year, in the autumn as the soil wets up. It should also be done in the same place, so growers should mark a GPS point in a representative and relatively uniform area, and work within a 10 m radius of that point.
“All scorecard indicators have threshold values (benchmarks) with a traffic-light coding. If they come back red, outside of the expected range for that indicator, it means there is something to investigate. This might involve an intervention or a different management approach to address that. If the indicator falls in the amber region, then this is borderline and an area to review more frequently. If the result is green, then continue the rotational monitoring. The results do involve interpretation. Knowledge of the field’s history is an important factor.”
AHDB plans to issue the final scorecard and supporting information in 2022.
For more results, from across the Strategic Cereal Farms network, register for Strategic Cereal Farm results week (15–19 November 2021), which will unite farm hosts and researchers in a daily webinar (12.30–2.00pm) discussing a different topic each day.