Increasing grass production on Irish dairy farms

Irish grassland dairy farms have experienced major grassland changes in the past 10 years. Grazing stocking rates have increased, chemical nitrogen (N) fertiliser levels have reduced and significant climatic challenges (wet spring, dry summers) have lead to increased levels of concentrate and forage supplementation at grazing.

Data from PastureBase Ireland (PBI) shows that dry matter (DM) production on farms has not advanced in line with increased grass demand, grass DM production has averaged 13.2t DM/ha/yr from 2014 to 2024 and 12.6t DM/ha from 2022 to 2024.

There now needs to be a refocus on increasing grass DM production at farm level. There are many factors that influence pasture DM production. The main factors include soil fertility, grazing management, use of grass clover swards and N input.

Soil fertility

To achieve high DM production, adequate soil fertility is required; a soil pH of 6.5 and index 3 and 4 for phosphorus (P) and Potassium (K).

While P and K are very important nutrients, soil pH below optimal (<6.5), reduces the nutrient use efficiency of applied fertilisers.

The most recent (2024) national soil analysis report for dairy farms shows that there is a very large proportion of soils significantly below the levels required for optimum grass growth and nutrient use efficiency.

Clover is widely considered a replacement for chemical N in grassland systems; however, clover will not establish or persist below soil pH of 6.5.

Grazing management targets

There are a number of key grazing management targets that are essential to be achieved to maximise overall herbage production during the grazing season.

A number of these targets are not being achieved at farm level, OFC is below target, on average 880kg DM/ha for the past number of years, which has a major influence on the level of grass growth and supplementation required in early spring.

Peak farm cover (mid-September) on farm is 250kg DM/ha below target at 850kg DM/ha. If farmers are to increase overall DM production (>14.5-15.0t DM/ha), there is a need to refocus on the targets identified.

Nitrogen input

It is important that chemical N fertiliser input and paddock clover content are aligned.

White clover has the ability to fix >80 kg N/ha, however, sufficient levels of clover in the sward (>20% – average across the year) are required to achieve this. If chemical N fertiliser is removed in the absence of adequate clover content, overall herbage production declines.

At the open day, a N strategy will be showcased based on an individual paddock’s sward clover content.

Nitrogen inputs are reduced on paddocks from May onwards, in line with clover contents, replacing chemical N by targeted soiled water usage.

To conclude, farm dry matter production needs to be refocused and increased on Irish dairy farms.

Grazing management, ensuring seasonal grazing targets are achieved, using precision N fertiliser programme and clover incorporation and maintaining above average soil fertility will assist in increasing overall herbage production.

PastureBase Ireland and Grass10 update

The first half of 2025 has seen almost optimal conditions for grass utilisation, driven by dry weather conditions throughout the spring period, the use of timely nutrient applications, and a real focus by farmers to graze early in 2025.

During the spring period, classified up to the 1 May in 2025 (within PastureBase Ireland (PBI)), farms grew an average of 2.3t DM/ha, which was 300kg DM/ha above the five-year average.

Despite this encouraging performance, the average farm did not achieve the target of 2.6t DM/ha grown by 1 May in order to have grown 15t DM/ha per year.

This shortfall was primarily driven by low opening average farm cover on many farms, a consequence of later closing dates last autumn and over-winter deterioration of the sward when snow fell in early January.

During the mid-season, some farms had become dry in early May, leading to a notable reduction in growth rates. Across the country growth rates dipped to 60kg DM/ha from a peak growth rate of 77kg DM/ha.

Rain arrived in late May enabling growth rates to maintain above 65kg DM/ha for every week since this point.

For the year to date, the average farm on PBI has grown 5.9t DM/ha, +600kg DM/ha more than the five-year average and 200kg DM/ha more than the 10-year average, positioning farmers well to achieve over 13.5t DM/ha on average across the year.

Grass quality has been an issue on many farms primarily driven by higher pregrazing yields (currently 1,580kg DM/ha), this needs to reduce to 1,400kg DM/ha to ensure high intake and low residuals. As farmers turn their attention to the second half of the year, the main focus must be on getting high quality grass into dairy cows with a secondary focus placed on managing silage supplies and ensuring high-quality silage, in the form of surplus bales, is gathered for the milking herd.

The autumn period of 2024 provided above-average growth rates and favourable ground conditions which enhanced sward utilisation which may not be the case in 2025.

Crucial to this plan is the creation of a fodder budget to quantify current available fodder stocks.

The fodder budget in PBI allows farmers to input their current fodder stocks on the farm (eg pits of silage and bales of silage), simply adding in expected animal numbers for the winter period, and the system then calculates the feed requirements.

Now is the perfect time to calculate fodder stocks to assess whether a third-cut of silage is required on farm. The key to planning for the winter period is to act early.

PBI personnel will be available in the Grassland village to discuss your personalised PBI inputs.