PRECISION technology has become routine on many arable farms for those seeking to drive crop yields at a more efficient cost but dairy farmers are now taking advantage of the benefits it can offer too.

At Stackpole Home Farm, near Pembroke, the farm’s inclusion in a new Nitrate Vulnerable Zone prompted brothers Nigel and Chris James to take a closer look at nutrient application.

During a Federation of Welsh Grassland Societies open day at the farm, farmers were told that the regulations had made the business more sensitive to nutrient use.

Intensive soil sampling was carried out in every field.

“Each field was sampled multiple times rather than the customary once,’’ said Chris. The resulting contour maps revealed the differing nutrient levels in each field.

“We were surprised at how nutrient levels varied between fields, there was no commonality between pH, phosphate and potash,’’ Chris explained. In a single field the indices could range from a pH of 5 to 6 and a potash of 0 to 2.5.

Armed with this information, potash, phosphate and lime could be targeted at the areas deficient in these elements.

Savings were apparent from day one because, in previous years, fields would have been blanket treated. “We were able to cut down on nutrient applications in the areas of the fields that didn’t need them,’’ said Chris.

“We use an equation to work out how much to apply to maintain our indices in subsequent years.’’

Farm manager Gethin Brown measures grass growth weekly using a quad bike-mounted plate meter. “That information allows us to compare ourselves to other similar sites,’’ said Mr Brown. “Our aim is not to increase production but to maintain it, using less nutrients that we would otherwise have applied.’’

There is an environmental benefit too, he added. “We are using our nutrients more effectively. We are targeting the fields that have low indices with our own slurries and farmyard manures.’’

The farm has a 9,000 cubic metre slurry store with capacity for five months of storage.

External contractors were used to sample and map the farm so there was no capital outlay. The service cost £22/hectare and will be repeated every three years.

Although farmers are concerned about the possible expansion of NVZs, the experience at Stackpole has been a positive one.

“It has forced us to take an interest in our nutrients. We are running a better farm as a result of that,’’ said Chris.

A herd of 1,100 dairy cows and 360 followers are run on 480 hectares of free draining limestone and shallower red sandstone. The herd is predominately New Zealand-bred Friesian with an average milk yield of 5000 litres at 4.3% butterfat and 3.65% protein. Fields are reseeded every 10 years using late heading perennial varieties.

The acreage available for grazing has been increased from 150 hectares to 200 hectares by the creation of an underpass which links two parts of the farm separated by a road. Previously, freshly milked cows could spend up to three hours in a holding field waiting to be turned onto fresh pasture but they can now move freely through the underpass.

The tunnel, created from 4.5-metre-wide pre-cast culverts, was a significant investment but it has allowed the farm to extend the grazing area. “Cows can spend more hours at grass and we have been able to include in the milking platform fields previously used for grazing heifers,’’ said Chris.

The open day, attended by around 150 farmers, was the first in a series of events being held across Wales to mark the 50th anniversary of the FWGS.