Upper Nisbet grazing trial a 'first' for Scotland

The five-year trial is being hailed as a first for Scotland, in that it will involve grazing cattle – and real time measurement of grass and animal performance – as opposed to the traditional grassland trials reliant on simulated grazing, ie cutting, which gives no indication of animal preference, grass palatability or animal growth.

Cropping at Upper Nisbet consists of cereals and grassland – supporting beef cattle – grown in a rotation. In this respect, the farm is a fairly typical mixed farming unit and is therefore an ideal site for the trial.

The trials field at Upper Nisbet is 8.4 ha and lies between 150-160m (490-525 ft) above sea level and has a north facing aspect. It is a free draining loam (Hobkirk Series) and is remarkably even across the field which is rectangular 560m long by 150m wide.

The field was soil tested prior to establishment and was remarkably even across the field, with, pH of 6.5-6.8 and P and K levels moderate to high. A soil health survey to measure soil organic matter (5.03%) was also carried out at that stage.

Prior to the trial, the field had been in cereals for the previous five years. The trial varieties and mixtures were sown on September 3, 2019, following the harvest of the preceding spring barley crop.

The field was ploughed and levelled and then sown on in good conditions on that date using a one-pass power harrow drill. The coulters were raised and the seed blown on and tickled in with the following tines. The drill tractor utilised GPS to divide the field and accurately sow 47 by 12m wide strips/plots, each of a different variety or mixture. The plots are all 140m long.

A late finish in a heavy downpour meant the field was not Cambridge rolled until a few days later. However, good soil temperatures in early September gave a good emergence and by October 24 there was a satisfactory ground cover. Sheep were then grazed across the entire field in December/January and all of the strips across the whole field now look well established and should be ready for grazing again by cattle at turnout in late April/May.

The cattle will be grazed on a paddock grazing system with, the field divided into 8 x 1.08 ha paddocks each containing six of the individual 12m wide plots/strips. The top and bottom headlands are sown with the farm’s standard grazing mixture.

The first five paddocks were sown with strips of single stand varieties of intermediate and late perennial ryegrass. These varieties are all grouped by heading date (relative ear emergence) going from 35 days in the first plot to 55 days in plot 30. It should be interesting to observe animal preference within each paddock of six varieties.

The final paddocks (6, 7 and 8) are sown with Watson Seeds bespoke mixtures and contain a wide variety of grasses and plants, including multi-species mixtures with herbs.

Cattle turnout in late April/early May will, hopefully, then achieve a grazing season of 210 days, or nine individual grazing ‘events’ across the plots. Stocking density, though, in this first trial year (2020) may have to managed carefully in order to avoid poaching on ground that has not yet established a sufficient turf.

Pre- and post-grazing sward density and dry matter yield of each plot will be measured using an innovative new pasture meter towed behind a quad bike. Technology advances in pasture monitoring systems have been driven by the dairy industry in New Zealand and a side benefit of the Upper Nisbet trial will be the utilisation and demonstration of this new tech on farm in Scotland.

Quality parameters in each plot will be measured monthly in the main growing season with the latest developments in NIR spectroscopy. These results will be presented in a format that relates back to the relative calorific and net energy values of each sample based on NDF, sugars, D-value, protein etc.

The cattle will be weighed and monitored on a regular basis which should then allow cross referencing of the utilised kg of grazed DM at an average calorific value for that period of grazing.

The fertiliser management of the field will be based on standard farm practice and all applications will be costed to give an accurate cost of DM tonnes per ha.

Data from the soil health survey of the trial field, carried out at the outset of the trial along with measurements of organic matter and worm counts, will be used as a baseline, allowing the trial to look at how these figures are improved under the various grass and clover varieties and mixtures.

The trial includes deeper rooting grasses including cocksfoot, Timothy and fescues alongside clovers, chicory, plantain, sainfoin and sheep’s parsley. The duration of the trial will allow monitoring of these species and evaluation of their contribution to soil health, compared to straight ryegrass stands.

Commenting on what he hopes to gain from the trial, Johnny Watson stated: “This trial aims to look beyond the recommended list to help us to shape suitable grazing mixtures for our customer base.

“The whole Watson Seeds team is excited about the prospects for this project and, along with host farmer, Robert Neill – who we are extremely grateful to – we look forward to showcasing the trial to all interested parties at an open day this coming summer.”