Farm Ireland

Wednesday 17 January 2018

Farm margins slashed by up to 40pc in years of heavy rainfall

Martin Ryan

Net margins on heavy soil farms can be reduced by up to 40pc in high rainfall years, according to new research at Solohead.

High rainfall years, such as this one, can reduce net income on a 40ha holding by up to €16,000, even with the best management practices being employed on the holding.

The strong association between soil wetness and profitability was outlined by researcher, James Humphreys.

A 25pc reduction in herbage production with the same inputs, difficult grazing conditions, longer housing, higher concentrate costs, lower body condition, lower milk yields, poor silage quality and an increase in the incidence of rushes and liver fluke were the main factors identified.


Annual rainfall at the farm has varied from 797mm to 1,336mm over the past decade or so. In 2008 and 2009, annual rainfall was 1,228mm and 1,336mm respectively, with the top soil waterlogged for 14 months of the 24-month period, while the water level remained close to the top for the remaining months.

The water table on the farm varies from 0-2m, averaging around 1m under good conditions, compared to 20m at Moorepark.

"If we get a centimetre of rain on this farm, it raises the water table by 16 centimetres," explained Mr Humphreys.

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"Over recent weeks we have had up to 50mm in one day, which brings the water table right up to the surface very quickly. We have been dealing with that situation this year and in recent weeks which has forced us to bring the stock off the land", he explained.

"Wet soil conditions have been identified as the most important factor limiting the utilisation of grazed grass on Irish farms.

"There are clear productivity gains to be made by solving the problems associated with wet soil conditions.

"The challenge is to develop management strategies to increase profitability on wet land," he said.

With an estimate that up to half the land area of Ireland is in need of drainage, ground water and shallow drainage systems are being evaluated, with costs per hectare ranging from €125 for mole drainage to €8,600 for a conventional system.


A key message at the open day was the need for a proper site investigation using test pits before commencing any drainage works to identify the most appropriate drainage system.

This decision depends on whether or not a layer is present (at a workable depth) that will allow the flow of water with relative ease.

If such a layer is present putting in a piped drain system at this depth is likely to be effective. If no such layer is found, it will be necessary to improve the water carrying capacity of the soil.

This involves a disruption technique such as moling, gravel moling or subsoiling in tandem with collector drains.

Indo Farming