Sowing cover crops in Co Louth

Cover crops play a central role in Gareth Culligan’s tillage operation in Co Louth. Earlier this year, he was recognised as the Philip Reck Soil Farmer of the Year by BASE (Biodiversity, Agriculture, Soil, Environment) Ireland.

Gareth exclusively uses direct drilling on his farm and is actively involved in the Footprint Farmers programme due to his strong commitment to improving biodiversity and the sustainability of his farming practices.

When the Irish Farmers Journal last visited Castlebellingham in the summer, Gareth had sown a cover crop after harvesting winter oats, and he also had a summer cover crop in another field.

While he acknowledges that this may not be entirely necessary, he prefers to sow directly into the field rather than using a disc to disturb the stubble, as he believes this minimises unnecessary soil disruption, which can harm the soil structure.

He intended to plant a cover crop following winter bean harvesting in mid-September but, with harvests delayed this year, he did not anticipate sowing any more cover crops.

Oilseed rape was planted in early September, keeping with his schedule.

Sustainable approach

When the Irish Farmers Journal next visited in early September, he had completed about half of his harvest, with some cover crops already beginning to emerge.

He explained his approach to cover cropping, which includes sowing a mixture of beans, peas, buckwheat and sometimes sunflowers first, followed by a cash crop of oilseed rape combined with white clover, phacelia and occasionally linseed.

This is known as companion cropping. This companion crop is left in the field throughout the winter.

By January, the peas and beans die off, while the other plants do not compete with the oilseed rape.

The crop provides essential soil cover over the winter, helping to retain soil structure and supplying nitrogen to the next crop.

Diverse mix with different roots

Gareth is experimenting with different species in his cover crop mixes. He notes the need for caution, as some species can potentially cause harm or introduce diseases – anything is possible.

Lucerne, alfalfa and chicory return each year, but he thinks that they don’t compete with the main crops. These cover crop mixes are beneficial because the various plants have different root depths, helping break up the soil.

Gareth appreciates how incorporating cover crops supports biodiversity, as some species produce flowers, contributing to overall sustainability on the farm.

Cover crops are generally sown in August and last until March. In the past, Gareth has often grazed these cover crops with sheep, but new grazing regulations on lieback areas have complicated this practice.

Incorporating the cover crops back into the soil now requires spraying them off with glyphosate. The challenge with direct drilling is that it pulls the dead plants into piles across the field, which can clog the tines.

Grazing cover crops is the most effective method, as it removes the green cover naturally, thereby reducing the amount of spray needed – a benefit for soil microorganisms. Additionally, grazing reduces slug populations, helping to protect the next crop and works better for his drill. Sheep also return nitrogen to the soil through their dung, whereas leaving the green cover to decompose consumes nitrogen during the breakdown process.

However, new grazing regulations have impacted Gareth this year. He needs to leave buffer zones and lie-back areas for grazing animals now.

Despite these challenges, grazing cover crops remains the more sustainable option for his farm.