Five large potato businesses are involved in a project that aims to compare seed and fertiliser recommendations made by Cambridge University Farm researchers based on their research experience against the farm’s usual practise.

The Potato Council grower collaboration project was started in response to concerns within the levy board about how much the research was used by growers, Rob Clayton of the Potato Council explains. “There were also questions about whether the investment in CUF research was giving growers value for money.”

CUF research, while well-managed and statistically robust, often requires a good depth of understanding from growers before it can be used to make managerial or logistical changes to benefit the farm, he notes. “For that type of research we thought we needed to do something different [to help farmers use it more effectively].”

David Firman

David Firman explained to growers at the East Midlands Potato day the differences
Cambridge University Farm advice had made to Duncan Worth’s growing programme

The something different has been to bring the researcher into direct contact with a small number of growers covering all sectors of the potato market in a project where comparisons are made between the standard farm practise with what CUF would advise based on their research in three areas: Nitrogen rates, seed rates, and, to a lesser extent, irrigation.

At the start of the project growers provide detailed information of their intended crops, such as yield and grading, and how they plan to achieve it, CUF’s David Firman explains. This standard management is then compared with CUF’s advice and where significant differences are identified field comparisons have been set up. “We’ve picked fields where the standard practise differs by more than 10%.”

For example, instead of a 1.5t/ha seed rate planted at 28cm spacings for a Maris Piper seed stock with a 35-45mm tuber count of 1270, CUF recommended planting at 38cm spacing, giving a seed rate of 1.1t/ha at Duncan Worth’s Lincolnshire farm this season – a cut of nearly 30%.

“Our calculations suggest that should have only a small effect on total yield, but that should be offset by a better size distribution and an increase in the premium baker fraction.”

For Mr Worth that would be a successful outcome. “We’re looking to improve marketable yield. If we have a gross yield of 24t/acre, we want a marketable yield of 22t/acre not 20t/acre.”

A second comparison on the farm is comparing fertiliser rates. The farm’s recommendation for the crop, which follows vining peas, is for 180kg/ha of N, CUF says 140kg/ha of N. “I would not expect anyone to see a difference at the moment,” says Dr Firman.

Rob Clayton Duncan Worth

Duncan Worth’s (right) 4500-acre potato farm is one of five farm’s selected to trial a new
way of rolling out research messages to potato growers, says Rob Clayton (left)

That is not too surprising, he admits. “Early on in the season you are unlikely to see a difference it is more about how long the crop persists. There is no point in growing a crop that persists until December if you want to defoliate in September.”

He expects the lower N crop to senesce a little earlier. “But the expectation is that it should persist long enough to not make any difference to yields.”

The results from all five farms will be published by the Potato Council, Dr Clayton says. “One of the prerequisites of being part of the project is that the information will be published.”

That should mean it is easier for the Potato Council to provide case study proof to other growers that the CUF research does have a practical application on farm, and to do cost-benefit analyses, he stresses. “Each of the growers also has a satellite producer or supply chain groups attached to it, which will also help to trickle the research out to other growers.”

CUF seed rate research

New seed rate guidelines that take account of the effect of seed age – measured as the period from emergence of the seed crop to the planting of the ware crop – on the marketable yield are at the heart of the recommendations CUF are using on the five farms.

“The previous recommendations were pretty crude, and made little account of the yield of different tuber size fractions produced,” Dr Firman says.

But different aged seed stocks can have a big effect on the numbers of stems a ware crop produces, and hence the numbers of tubers and their size. Taking seed size, age and factoring in target yields and optimum tuber size allowed CUF to make more accurate seed rate recommendations, he explains.

New seed rate guidelines for Estima were published earlier this year, with Maris Piper, Maris Peer, Hermes, Saturna and Lady Rosetta recommendations due to be released in time for planting next season.

Grower collaborators

  • North Norfolk Potato Growers
  • Strawson Farming
  • WB Daw
  • South-West Agronomy Group
  • AH Worth