River Blackwater Catchment Series: Nutrient balance driving profit (2025)

Agriland Media Group is delighted to collaborate with Dairygold to bring you the River Blackwater Catchment Series.

Dairygold milk suppliers Thomas and Christopher Kenny from Mourneabbey, Co. Cork are milking 120 cows with one eye on their nutrient balance, which is driving efficiency, sustainability and profitability on their farm.

Christopher and his father, Thomas, manage their efficient family farm, where they are milking 120 high economic breeding index (EBI) cows with impressive productivity.

The farmers won the Mallow Regional Dairygold Milk Quality and Sustainability Awards in 2023, for their sustainable production practices.

The milking platform is 120 acres, with 40 acres of that used for first cut silage, which Christopher said can leave them tight on grass in the middle of the summer.

The farm has an organic stocking rate of 223kg of N/ha at this moment in time, which Christopher expects will have to be reduced to 220kg of organic N/ha in the coming year.

The father and son have been in farm partnership since 2017 and have since increased profitability on their farm by improving their herd’s EBI, implementing targeted slurry and fetiliser application, reducing meal consumption, and maximising the number of days the herd is at grass.

The use of Sensehub collars, energy-saving equipment, and solar panels – which supply 24% of the farm’s electricity – also contribute to overall efficiency.

Biodiversity is an important aspect of their farm business through forestry, mature tree lines, and clover incorporation, which also decreases their nitrogen fertiliser requirement.

The Kennys’ dedication to efficiency, innovation, sustainability, and farm performance ensures their dairy operation’s success.

Nutrient balance

The Kennys’ farm is located in the River Blackwater catchment area. Any potential leaching of nitrates or overflow of phosphorus or sediment could impact the River Blackwater.

The Kennys are aware of this risk and are therefore doing everything in their power to produce milk solids in the most sustainable and efficient way possible.

The Kennys are in a comfortable position when it comes to slurry storage but plan to avail of the 60% TAMS grant to put in extra storage for their parlour washings, as they feel they will be tight on space with new regulations to come.

The slurry is applied using a trailing shoe, allowing for efficient use of nitrogen (N), phosphorus (P), and potassium (K). They began applying slurry in the second week of February when conditions improved, and soil temperatures rose.

Christopher mentioned that: “Ideally you want to hold on to your slurry until you need to spread it, as opposed to spreading it because you are under pressure”.

Spreading in favourable conditions considerably improves a farm’s nutrient balance, as the nutrients are effectively absorbed by the soil to promote grass growth. This increased grass production can subsequently lead to a higher yield of milk solids.

Approximately one third of the Kennys’ farm includes 20% clover, which reduces the reliance on chemical nitrogen and further decreases the farm’s nitrogen balance.

In terms of fertiliser usage, the Kennys keep it very simple – they spread protected urea in early spring, followed by protected urea with sulphur, and then use 18-6-12 to correct soil indexes during the main grazing season.

All fertiliser is spread strategically using the results from soil samples which are updated every two years. The soil results feed into the formation of a nutrient management plan (NMP).

The Kennys have an N balance of 186kg of N/ha with a P balance of 5.8kg of P/ha. They are constantly striving to improve overall nutrient balance to improve their farm efficiency and their profit margin.

Farm efficiency

The Kennys’ herd has an average Economic Breeding Index (EBI) of €264, placing it within the top 1% nationwide. Their cows weigh approximately 580kg.

Last year’s production yielded 6,570kg of milk per cow with 547kg of milk solids per cow. Each cow was fed 1.3 tonnes of meal, consisting of soya hulls and dairy nuts, which was approximately 300kg/ cow more than usual due to unfavourable weather conditions.

The Kennys use sexed semen on maiden heifers and second to fifth lactation, which is followed by conventional dairy semen on late calvers and beef straws on cows not fit for breeding replacements.

The selection process for cows used in dairy artificial insemination (AI) is based on evaluation of the best genetics within the herd and consideration of their genomic assessment along with data from milk recordings.

The heifers calving down this year have an EBI of over €300. The Kennys have 25 replacement heifers entering the herd annually, and they sell the surplus.

Improving EBI year on year will also reduce a farm’s nutrient balance as individual cows will more efficiently in converting grass and meal, into milk solids.

Days at grass will also reduce the nutrient balance, and provides the cheapest form of feed for cows, and the best returns in milk solids.

The Kennys put their cows out to grass at the start of February and started the second rotation on April 10.

The Kennys are also signed up to undertake a number of water quality improvement measures under the ‘Farming for Water’ European Innovation Partnership (EIP).

The Kennys have taken on the following measures:

The Kennys are getting paid for measures that they were already undertaking such as testing slurry, utilising a nutrient management plan and managing a critical source area (CSA).

The farm’s soil type is quite mixed. A lot of the farm is free draining while other parts are quite heavy. The Kennys therefore have to deal with phosphorus run-off and flow pathways, and nitrate leaching.

Managing the farm’s CSA is crucial due to its high connectivity to the drainage network, potential risk to water bodies, and difficulty in grazing and travel because of wet conditions.

The management of this area includes preventing animal access during the shoulders of the year and avoiding nutrient spreading nearby. Both practices are already employed by the Kennys.