In practical terms, two 700kg silage bales per acre at 30% dry matter are close to 1 tonne DM/ha. At 68kg DM/ha/day, farms were growing roughly one bale per acre each week. By 27th July, 35kg DM/ha/day was only around half a bale per acre per week.
That strong starting position mattered. With a normal AFC target of about 2,100–2,300kg DM/ha, many farms entered the dry spell carrying a useful grass buffer.
Figure 1. NI dairy grass growth compared with the nine-year GrassCheck trend. The shaded period marks the near-zero rainfall period from 7th to 20th July.
From resilience to rapid decline
Across 20 AgriSearch weather stations, average rainfall between 7th and 20th July was less than 1mm, and 19 stations recorded none in the first week. Downpatrick recorded a 30-day dry spell from 2nd to 31st July. Some 65% of network rainfall fell between 25th and 31st July, after growth had already been hit.
Grass initially remained resilient as swards drew on soil moisture. By 13th July, growth was 60kg DM/ha/day, only 3% below trend; by 20th July it was 47kg, and by 27th July just 35kg — 42% below the expected 61kg.
County results show why advice had to be farm-specific. Down fell from 66kg DM/ha/day on 6th July to 19kg in early August, while Derry/Londonderry recovered from 25kg to 50kg after late rain. Rainfall varied within counties, so recovery differed between grazing platforms.
Protecting farm cover
As growth dropped below demand, farmers acted early, bringing silage ground into the grazing platform, removing cull cows and introducing silage or meal. This reduced demand, extended the rotation and helped keep AFC above 2,100kg DM/ha.
Silage feeding rose from 9% of reporting farms on 13th July to 35% by 20th July and 50% by 27th July. Mean AFC fell from 2,454kg DM/ha on 6th July to 2,276kg, but remained within the seasonal target.
There is a simple principle behind protecting cover: grass grows grass. Keeping enough cover on the grazing platform left green leaf to respond when moisture returned. GrassCheck advice was to keep measuring, reduce demand where necessary and protect residuals rather than graze stressed swards too hard.
But there is a balance. Milk pays the bills, not the amount of grass standing in the field. Extra cover provides insurance in a dry period, but overly heavy pre-grazing covers can compromise performance. DairyNZ work illustrates the point: cows grazing around 2,900kg DM/ha produced 6% more milksolids than cows offered around 3,400kg DM/ha.
The aim is enough high-quality grass for milk production while protecting the next rotation: use too much of the buffer and little may be ready when rain comes; carry too much heavy grass and quality can suffer.
Figure 2. Mean and median average farm cover (AFC), the seasonal target band, and the share of reporting farms feeding silage as dry-period pressure increased.
Grass quality also changed, dry matter rising from 17% on 6th July to 22% by 27th July, while crude protein fell from 17% to 14% by 20th July before recovering to 17%. ME remained close to 11MJ/kg DM, and the higher DM helped explain why paddocks often contained more feed than they appeared to.
Many farmers with good clover content felt those swards were slightly more resilient. CloverCheck plots at AFBI Hillsborough supported this farmer observation: through much of July, grass-clover plots receiving around 68kg N/ha or no fertiliser N maintained higher growth than grass-only plots receiving 270kg N/ha. This single-site comparison provides supporting evidence of clover’s potential under moisture stress.
At the recent GrassCheck meeting, advice was to avoid heavy ‘catch-up’ N applications after the dry spell and target N where grass had the greatest potential to respond. Farmers also discussed soil N mineralisation and the likelihood that some N remained available from previous fertiliser and slurry applications, with moisture rather than N supply having been the main limitation. The preference was therefore for a ‘little and often’ approach. Timing remained the key question: whether to apply ahead of rain or allow background soil N to support the initial recovery before applying fertiliser once there was greater confidence that wetter conditions would continue. K and S should also not be overlooked, with K important for water regulation and S supporting nitrogen-use efficiency.
Water infrastructure in a dry period
The dry July highlighted water infrastructure. Hot, dry weather and higher dry-matter grass increase demand: 100 cows at grass can drink around 6,500 litres a day, with individual intake exceeding 100 litres/day in hot conditions.
Replacement rate matters as much as trough size. For 100 cows, around 20 litres/min is a useful benchmark. Meeting advice also highlighted around 9 litres of trough capacity/cow, drinking space for about 10% of the herd (around 450mm of trough edge per drinking cow) and 1¼–1½-inch looped pipework where appropriate.
Farmer findings: infrastructure creates flexibility
What continues to stand out within the GrassCheck group is how quickly farmers adapt. At a recent meeting, the message was simple: good infrastructure is central to effective grazing in Northern Ireland. Laneways, paddock access, fencing and crossings provide flexibility through wet spring and autumn shoulders, while July showed that water supply and well-positioned drinkers are just as important during dry periods.
Farmers felt these investments need to be considered in the context of the whole farm. In fully housed systems, investment in sheds and feed space is often regarded as essential, yet infrastructure within grazing systems can sometimes be overlooked or viewed as expensive.
Roadway costs of around £15–£25 per metre were discussed. One group member highlighted that opening up a sizeable area of the farm with a new laneway, drinkers, fencing and a road crossing cost less than the contractor bill for the farm’s second-cut silage the previous year. It is one example rather than a benchmark, but it puts grazing infrastructure costs into a useful whole-farm context.
The group also felt that poor access, inadequate laneways and limited paddock infrastructure can make grazing unnecessarily difficult and may contribute to some farmers questioning grazing-based systems. If grazing is to remain an attractive option for the next generation, continued investment in infrastructure will be essential to make it practical, efficient and easier to manage. That investment can give farmers greater flexibility and help make better use of one of Northern Ireland’s key advantages — grazed grass as a low-cost feed.
A changing grass-growing season
The dry July also fits a longer-term GrassCheck trend: over the last 25 years, the data show better early-season growth, a later peak and greater summer variability.
Longer-term projections suggest stronger early spring and late autumn growth, alongside more volatile and often lower mid-summer growth — potentially a longer, but less predictable, grass-growing season.