A large proportion, approximately 30 per cent of milk produced in Ireland originates from farms where the soils can be classified as heavy.

This is according to James O’Loughlin of Teagasc’s Animal and Grassland Research and Innovation Centre in Moorepark, Cork who was giving an update on the latest developments in its heavy soils programme.

“Heavy soils add complexities to the production system that are aggravated by inclement weather conditions like those experienced in 2012 and spring 2013. The heavy soils programme was initiated in 2009 to investigate the challenges facing farmers on heavy soils,” he explained to a crowd of more than 150 people at the recent Future Weather, Future Farming conference.

Participating farms in its programme, which were selected due to the challenging soil types, included: Macroom and Kishkeam in Cork; Castleisland and Listowel in Kerry; Athea, Limerick; Rossmore, Tipperary; and Doonbeg, Clare.

In his presentation, O’Loughlin explained the impact of bad weather on dairying on wet land. Take grass production as an example.

“Average grass production in 2011 on the seven farms was 11.6 tonnes of grass dry matter (DM) per ha,” he explained. “This was reduced to 7.8 tonnes DM per ha in 2012 showing the huge effect the wet summer of 2012 had on these farms. Compounding the drop in grass production was the difficulty in achieving good pasture use due to the very wet and soft ground conditions, farms with a good infrastructure of well laid out paddocks and roadways fared best.”

According to the Teagasc researcher, the continuing downward trend in soil fertility nationally is also evident on the heavy soils programme farms, with recent soil analysis showing suboptimal results.

“The soil results 2013 (2010 results in brackets) were pH 5.73 (5.54), P 4.16 mg/l (5.54mg/l) and K 84.04 mg/l (116mg/l) To establish and maintain good ryegrass swards soil fertility has to be at optimal levels (pH 6.2, P 5.1 – 8, K 101 – 150),” he outlined.

All participating farms identified two ha of land to be drained, he said.

“Soil type ranged from peat to carboniferous shale to red sandstone till. After site investigation, the most appropriate drainage solution was selected. Deep drains (1.7 m), shallow drains (0.9 m), mole drains and gravel mole drains were installed and ripping was carried out where necessary on the farms during the summer of 2013 when weather conditions were ideal.”

He explained the drainage costs ranged from €3,000/ha for collector drains and ripping, €6,000/ha for deep drains to €8,100/ha for gravel mole drains with average cost of €6,133/Ha for all farms.

Measurements of milk and grass production together with meteorological and drainage flow rates are ongoing and will be used to evaluate the benefits of the drainage work, he said.

In conclusion O’Loughlin stressed the increased productivity on heavy soils requires clear management decisions that mitigate the risks in farming such land.

“The capacity to grow adequate quantities of grass in a three-year cycle is dependant on high utilisation of productive perennial ryegrass swards and the provision of adequate silage reserves, at least 0.5 tonne DM/cow.

He added that stocking rates must be matched to the grass growth and utilisation capacity of the farm. Based on potential grass grown of 12.5 tonnes DM/ha with all winter feed requirement conserved within the farm, including reserve, the optimum stocking rate is 2 LU/ha.