Feed and fertiliser savings after a bumper year for grass

Despite a challenging start to the 2021 grazing season, average grass growth to date is now 9.3 t DM/ha according to AHDB’s Forage for Knowledge (FFK) monitoring programme.

John Forbes, Herd Manager at Wolfhall Farm, shares how managing grass has taught him about the importance of growing and utilising grass, and targeting the shoulders of the season.

“The 2021 grazing season got off to a challenging start with some poor weather in May, and the first cut of silage was taken around two weeks later than we planned,” says John.

Wolfhall Farm near Marlborough, Wiltshire has contributed is grass growth and quality figures to FFK since 2013 when owner, Tom Blanchard, started monitoring grass as the farm changed to split-block calving and rotational grazing.

The herd now comprises 320 spring calvers and 230 autumn calving crossbred cows. The spring herd produces 5,500 litres from 1 tonne/cow of concentrates, while the autumn calving cows average 8,000 litres from 2 tonne/cow and are fully housed from around 10 October. Turnout is usually in the middle of February, with both herds spending 270–280 days at grass.

John uses his weekly grass walk to operate a highly flexible system of 47 paddocks, ranging in size, but prioritising spring calvers at turnout. John says: “I can send cows in two different directions – without hold-ups or getting the two groups too close to each other – because we have the infrastructure.”

Having a split block herd can produce some challenges when grazing. “It takes a bit of tinkering to balance everything,” admits John. “If you get it wrong, it goes very wrong. It’s a challenge to manage. We have one grazing platform, and most of the pinch is in the spring.”

John originally planned to clamp all silage this year, but the first cut was so bulky that the second cut, taken six weeks after the first, and the third cut, another six weeks later, were both baled.

“The reason we made all the silage was to make ourselves more resilient to drought, as last year we only grew 20kg DM/ha/day grass in May and June because of the dry conditions. But this year we haven’t had an issue and it’s been a bumper year,” explains John. “We’ve nearly grown ten tonnes DM/ha already with around 120 days of grazing left – it’s the year that keeps on giving.”

Conditions have been so good that John applied 50kg less Nitrogen than this time last year as the grass hasn’t needed it, with no impact on return.

Despite the 2020 drought, Wolfhall Farm had its highest grass yield since they began measuring with an average of 13.5 t DM/ha: a significant increase on 12 t DM/ha in 2019. 

“What made the biggest difference was to close up autumn grass instead of grazing it off. This carried grass over into spring and pushed growth early in the season. Inputs have stayed the same,” says John.

Paddock yields ranged from 10–18 t DM/ha with an average ME of 12 MJ/kg and protein at 22% (peaking at 29% this spring) for most of the year. “It makes you think twice about putting bought-in protein into the mixer wagon,” John adds.

Concentrate usage has been minimal this grazing season. “Through May we were feeding 2kg of cake in the parlour, and in June and July we only fed 1kg to help cow flow through the parlour. The majority of the milk has come from grazed grass,” says John.

Grass situation across GB

The ideal weather conditions through August have led to a boom in grass growth across GB with the average grass production to date ahead of the 8.5 t DM/ha produced to the middle of August in 2020, Figure 1.

Figure 1: Forage for Knowledge GB grass production trend 2013 – 2021.

Annual grass production has increased steadily, above the 11.9 t DM/ha reported in 2013, but drops were reported in 2018 and 2020 to 13.3 and 12.7 t DM/ha respectively. Last year’s grazing season brought a mixture of challenging conditions from the heavy rain and flooding in early spring, followed by a hot and dry summer leading to drought in some areas.

By rotationally grazing according to how the grass plant grows by using the three-leaf principle, the grass remains in a vegetative state and stays leafy. Well-managed grass has an ME of 12 MJ/kg throughout the grazing season; this makes it more palatable to cows therefore increasing intakes.

Forage for Knowledge

AHDB’s Forage for Knowledge programme, aims to help farmers improve their grazing management. Now in its twelfth year of data collection, as well as grass growth figures it provides dry matter, metabolisable energy (ME) and crude protein (CP) figures enabling farmers to benchmark against other farms on an interactive dashboard.

The programme highlights that the grazing season to date has been a year of big peaks and troughs, causing management challenges across the 31 rotational grazing contributor farms across Great Britain.

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