Green Cover Case Study

Gordon Pirie & Son

“Working closely with Kings over the years has allowed us to refine the cover crops we use and select options that offer most adaptability to our local climate and their ability to establish rapidly."

        Brian Pirie, farmer

Green cover now forms an integral part of the cropping rotation at Gordon Pirie & Son on Castle of Auchry Farm in Aberdeenshire, leading to big benefits for the farm’s biodiversity. Farmer, Brian Pirie, has worked alongside Kings Crops technical advisor, Ed Jones and Frontier crop production commercial manager, Steven Penrice, to fine-tune his cover crop mixes and ensure the best benefits to soil health.

Brian Oliver Pirie small

 Brian and Oliver Pirie

The introduction of cover crops was not merely due to compliance with regulatory schemes, but stemmed from a conviction that it was the ‘right thing to do’ on the farm.

The farming enterprise, located in the northeast of Scotland, spans 780 acres of arable land comprising spring barley, oilseed rape, winter wheat and winter barley. As part of several sustainable farming objectives, the rotation also incorporated green manures under the ‘green manure following overwintered stubbles’ option of the Agri-Environment Climate Scheme (AECS). Their inclusion has proven to be very effective, with the following spring crops seeing a 50% reduction in applied nitrogen.

Cover crops are also delivering benefits, with the farm meeting Scottish Ecological Focus Area (EFA) requirements by sowing them after a spring barley harvest. 

Finding the right mix

The cover crops have become an integral part of the farm’s system overall and, even before the requirements set by EFA were in place.  Today ,100 acres of the land are now dedicated to cover crops and the farm has seen tangible benefits.

“We’ve been cover cropping for about six years now and we’re working towards increasing this to 150 acres over winter in the future,” says Brian.

“We were initially motivated by cover cropping to improve our soil’s fertility, increasing our organic matter levels and helping reduce soil erosion due to the lack of available organic manures to the farm. Working closely with Kings over the years has allowed us to refine the cover crops we use and select options that offer most adaptability to our local climate and their ability to establish rapidly.”

Ed adds that the selection of mixes at Brian’s farm is divided into three distinct categories, influenced by the requirements of the AECS, EFA and ongoing trials taking place. 

“The green manure mix is designed to meet the AECS requirements alongside providing soil health benefits and providing a boost to the following spring crop,” he says.

“It’s formulated for establishment in the spring and to last through the winter, providing a well-structured and nutrient-rich soil for the following crop. It uses a selection of clovers due to their hardiness and ability to enrich the soil, making it ideal for the AECS criteria and supporting subsequent crops.”

The cover crops used at the farm are chosen to meet Brian’s personal and EFA requirements. More recently though, further steps have been taken through the introduction of cover crop trials, with Brian working closely with Ed and Steven to explore different methods for crop establishment. The mixes being trialled include various combinations of rye, radish, phacelia, buckwheat, linseed, vetch and oats.

Ed explains: “The aim of the trials is to establish cover crops that can thrive in the specific conditions of Aberdeenshire and Northern Scotland, where the window for planting is shorter compared to other regions.

“Rye and radish are chosen for their rapid growth and ability to establish quickly, with the inclusion of phacelia and other species helping to introduce varied root systems which offer benefits like soil aeration, reduced compaction and improved drainage.”

Vetch Nodules

Establishment methods

Steven says the trials will allow them to assess the effectiveness of broadcasting seeds into a standing cash crop as a means of early establishment compared to more conventional methods.

“Broadcasting is being explored as a strategy to get cover crops in the ground earlier than usual, which is particularly important in regions like Northern Scotland,” says Steven. “Part of the trial also involves establishing crops in the traditional way to ensure we have a baseline for comparison.

“By comparing the two, we hope to highlight the potential advantages and disadvantages of each approach in terms of crop growth and overall biomass production.

The trials are not just about testing methods of sowing but about exploring the viability of different crop species in the local ecosystem too.

“A key focus is to also look at the various mixes of cover crops too, as it’s key to understand which combinations may be more effective under specific climate and soil conditions.”

So far, the farm’s exploration of different mixtures and approaches has shown promise, with particular merit for broadcasting cover crops in advance of harvest. Ed noted that initial observations showed it can lead to quicker establishment and higher biomass.

“Upon first inspections, radish as a species seems to have established well by broadcasting, whereas smaller seeded species such as phacelia have not spread as wide,” he says. “The farm’s standard establishment of cover crops, though not as advanced, has still performed satisfactorily too.

“These trials have only been conducted across a single year so far though, so further monitoring will be important over a number of seasons to ensure we get the most valuable insights possible.

Vetch Nodules smallRye and Radish Blend Rooting small

Knowledge exchange

The opportunity to share learnings is a vital component of the trials at Castle of Auchry Farm.  Through continued collaboration with Kings, Brian is able to host on-farm events and trial tours for other farmers in the region.

“Growers get the opportunity to observe first-hand the results of our different cover crop establishment methods, and it’s also a chance for them to connect with others facing similar challenges.”

Steven adds: “Events like cover crop meetings at Brian’s farm are invaluable. They provide a real-world context for learning, enable the sharing of practical experiences and help build a supportive community among growers, all of which are essential for the advancement of sustainable farming practices.”

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