Teagasc research has shown that perennial ryegrass will struggle to persist in wet soil. It notes that drainage is a key area farmers must address before thinking of reseeding.
Teagasc staff in the Grassland Department, Dairy and Beef Specialist teams in Moorepark have done extensive research on reseeding. It notes that reseeding levels in Ireland are low. Less than 2% of our annual grassland area is reseeded annually. As grass is our main feed during the main grazing season, and the primary source of winter forage in the form of grass silage, the low level of reseeding must be addressed.
According to Teagasc, on heavy soils the rate of water infiltration is significantly reduced compared to free draining soils, resulting in a significant reduction in grass production and utilisation. Land drainage can improve the water movement off a paddock or field.
Teagasc highlight that land drainage must be approached in a strategic and planned manner if it is to be of benefit to the productivity of the farm. All other land on the farm should be highly productive before attempting to drain and reclaim wet land. Soil fertility must be addressed before drainage and reseeding.
When undertaking land drainage, it is best to invest in those areas that will give the greatest return in terms of grass production and utilisation.
• Clean all fences, cut hedges and clean out old drains before reseeding
• Undertake drainage before reseeding
• Proper site and soil assessment must be undertaken
• Dig test pit(s) to identify drainage problems
• Soil fertility must be corrected
• Good farm infrastructure should be in place
• Select appropriate drainage system to address the problem specific to the field
• Shallow drainage system (e.g. mole drains) – use on very impermeable soil
• Ground water drainage system – use where there is a permeable layer in the soil (identified through a test pit)