Consistency is Key in a Changing Climate – Precise Mag – Jim Clark

Posted on

Setting up and running a successful AD plant in a high rainfall, grassland and intensive dairy area takes some management.

Located just east of Dumfries in south west Scotland, Tinwald Power runs a 1MW anaerobic digestion plant fuelled with a mix of grass, forage rye and whole crop silage, supplemented as necessary with livestock manures.


William Tuer of WST Rural, the system manager says that ensuring consistent feedstocks is vital to the smooth running of an AD plant.

With typically 1200mm of rainfall (by way of contrast Lincolnshire usually has approx. 600mm per year) growing crops is very weather dependent with robust systems of establishment and harvest necessary.

AD Requires Attention to Detail

It’s a cliché to talk about juggling, but there are many aspects to consider, manage and balance to keep the plant running at its optimum.

In this scenario all parties have their part to play:

The Contractor:

John Watson of Drew Watson & Co provides the labour and machinery for day to day plant running, alongside the establishment, growing and harvesting of the crops.

The contractor is responsible for loading the AD plant at the correct time with the appropriate quantities (and proportions) of the feedstock forages to ensure consistent biogas generation and hence electricity production via the CHP plant.

For Tinwald Power, the key attributes of a successful contractor relationship revolve around access to staff, equipment and technologies to monitor and manage.

Drew Watson’s equipment has been spec’d for biogas and includes a John Deere 8800 self-propelled forager equipped with HarvestLab (John Deere’s real time NIR sensor) to monitor the forage as it is ensiled.

Another factor vital to the success of the team approach is that the contactor has sufficient equipment with the capacity to cope with the vagaries of a maritime climate in south west Scotland. John can draw on up to four self-propelled foragers if required to ensure timely harvest.


About Tinwald Power

Biomass spec – chop length 4mm down. Kernel processing for cereal crops (maize, hybrid ryes and wholecrops, wheat or barley).

The plant was set up by an investment fund in 2015 on a lease in Tinwald Estates, the operation was bought fully in-house this year with the operations team intact.

1 MW AD Plant

Fuelled from energy crops and farm manures. Biogest plant. Owned by Tinwald Estates and managed by William Tuer (plant and business management) and John Watson (agricultural contractor and day to day operations manager).

Plant Rebuild

It’s been a challenging four years due to mechanical limitations, hence the plant is now being refurbished with a view to improving efficiency of resource conversion and specific power output and resilience to varying inputs.

Farming Business – JCJ Farms (Part of Tinwald Estates)

Approx. cropped area 545 ha, rotation – grass, wheat, rye, forage maize.

Contracting partner

Drew Watson & co. four self-propelled foragers and supporting equipment available.

Agronomy service

Jim Clark

The business benefits greatly from the close and transparent partnership with Jim Clark from Hutchinsons, giving recommendations for drilling dates, digestate application planning, crop protection, liquid fertiliser, rotation planning etc.



A series of management tools ensure traceability and time stamped records for all critical aspects of the production cycle have been developed. The has allowed easy information sharing between John Cunningham Jardine (as the owner), William as manager and John Watson as operations and delivery partner for all cropping.

These critical points include incoming feedstock specification, anaerobic microbiology and performance which ultimately affects electricity production. For instance, the CHP plant (Combined Heat and Power) has a maintenance contract which stipulates a guaranteed uptime. In practice, this includes routine checking, remote monitoring and recording. The results are factored into the plant management.

Open source management tools

William Tuer works with Google Analytics to blend different data streams into one dashboard. Some, or all elements of this dashboard can then be shared with the various stakeholders as required, either on a routine or task basis.

Feeding the hungry beast

The Tinwald Anaerobic digestion facility in Dumfries is a hungry beast; one that needs feeding consistently with quality crop. Achieving this season in and season out, needs a team approach involving agronomist, farmer and AD specialist & contractor all working together.

On the 545ha of cropping at Tinwald, ryegrass, forage rye, maize and whole crop are grown to feed the AD unit. “Seasonal factors influence the type and quality of feedstocks available, and up here this is exaggerated because of our northerly location, so careful planning and monitoring is needed to ensure the right mix is maintained throughout the year,” says agronomist Jim Clark of Hutchinsons.

“More recently, we have added forage rye into the rotation, as this reduces our dependence on grass and whole crop – and helps to spread the risk.

With the constant pressure of producing a quality crop to feed into the unit, we have to make the most of the land we have available and ensure that what is coming off it is the highest quality possible.”

“To achieve this, myself, the farmer John Cunnigham Jardine and AD specialist and contractor William Tuer all work together as part of a cohesive team driving timings, advice and forward planning,” he says.

“As an agronomist I am always looking for ways to improve poorer performing areas of fields and any opportunity to delve deeper into yield data and link precision technology to agronomy and farm management decisions is of immense value,” continues Jim.

“We have been yield mapping the grass, whole crop wheat and rye so we have the data on what was coming off particular areas of the field, but I wanted to find a better way of using the data to gain a clearer understanding of what is happening in every part of the field.”

“We uploaded all of our existing yield maps onto the Omnia system. From these we are able to produce a yield performance map which identifies and map areas of fields by categorising them in terms of consistency of performance such as poorly consistent yield, good consistent yield etc.”

Jim has been able to take this yield performance mapping a step further by incorporating the relative costs of production providing a clear insight into what it is costing to grow the crop in different areas of a field.

TerraMap soil scanning infographic“We are now taking this one step further and looking at redefining the way in which we map our soil nutrients, and in the spring will be using the new TerraMap soil nutrient mapping service,” he adds.

TerraMap uses gamma-ray detection technology that delivers resolutions of over 800 points/ha, providing high definition mapping of all common nutrient properties, pH, soil texture, organic matter and CEC as well as elevation and plant available water.

This methodology means that it is not affected by soil moisture, compaction, crop cover or cultivation state, so there are very few limitations to when it can be used.

“The results from TerraMap will help us to address why some areas are lower yielding and can be used in Omnia alongside all of the other mapping criteria to redefine what and how we manage our soil nutrients going forward, allowing for more precise and better targeted use of inputs.”