‘Every extra tonne of grass grown increases profits by €173 per hectare’

THREE whiteboard farm maps hang on the wall of the Heffernan dairy in Dunnamaggin, Co Kilkenny.

The maps show the soil fertility status, weekly grass measurements and slurry applications on each paddock, and are updated as appropriate.

This provides a vast amount of information about the grass on the farm at a glance, and the strategy was central to their winning the Leinster Grassland Farmer of the Year award in 2017.

Mark Heffernan farms in partnership with his brother Liam and his parents Billy and Mary.

Five years ago, Mark (pictured) said they got an “awful shock”. They had just received the results of soil tests which showed that their farm’s P and K levels had “hit the floor”.

At the time, they were soil testing every five years. Now, they test all soils at least every two years.

Up to 2008, the home farm comprised 95ha and had a mix of enterprises — 40 dairy cows, 300-400 breeding ewes, cattle and tillage.

With both Liam and Mark interested in farming, the family decided to jump fully into dairying. Their objective is to grow lots of grass and convert that grass into milk solids.

The herd has grown steadily and now numbers 450 cows, while the farm consists of 200ha, in three blocks, having taken on a number of leases.

Growth in cow numbers has not only been matched by an increase in land base but also an increase in the grass grown per ha.

This increase is a staggering 50pc, up from 12.6t/ ha in 2008 to 19t/ha in 2017.

“Every additional tonne of grass grown per ha will increase profit on a dairy farm by €173/ha,” said Mark.

The Heffernans apply for a Nitrates Directive every year and a nutrient management plan is drawn up by their Teagasc adviser. This forms the basis of their fertiliser and slurry plan for the year.

Another critical element of their grass management is grass measurement, which they began a decade ago. Now they walk the farm weekly, and twice a week at times of high growth. Last year, grass cover was measured 50 times across the entire farm.

Soil tests in January 2017 showed that about 60pc of the farm was deficient in lime and potassium. Since then, they have spread 800 tonnes of lime.

This was done by a contractor, about 1.5-2t per acre — “not too much at a time,” said Mark — after silage was cut or when ground was otherwise bare.

They have also spread fertilisers high in K (muriate of potash, 50pc K) in autumn, to help fix their K deficiency, while they target slurry on paddocks which are low in soil K or that are cut for silage.