Improvements in potato management resulting from applying Cambridge University Farms research are increasing yields and cutting input costs on two Norfolk farms, delegates at the Cambridge University Potato Growers Research Association annual conference heard.

Saleable yields from store had increased by 10% from an average 43t/ha in the 1990s to 46.9t/ha in the period between 2002 and 2008, B&C Farming’s Tony Bambridge said.

CUF had helped the Marsham farm with its irrigation scheduling since 1992, he said. As a result he had data from each crop recording planting date, date of first and 50% emergence and weekly ground cover figures until late August. “We also do yield digs in mid-August every year.”

Analysis of 77 Maris Piper crops showed how management of crops had changed since the 1990s, he said. Average planting dates were now a months later (18 April v 21 March), which pushed back emergence by three weeks and tuber initiation.

Later planting was a result of recognising the need to plant in better soil conditions. “When you see a bad crop, my immediate reaction used to be blame the seed or the fertiliser, never think it could be something we’ve done wrong.

“But CUF did a lot of work looking at the effect of compaction, putting some numbers of how root growth was affected by compacted soils.”

Penetrometer readings on his farm, which measure soil resistance, highlighted where his soils were compacted to a degree where root growth was affected, he said. “Where we had three Mega Pascals readings, we were effectively growing the crop in 35cm of soil.”

Other changes in management had been the result of the drive to produce a more uniform crop with greater marketable yield and an increased larger-size fraction, he said.

The move from chitted to unchitted seed produced a more even crop that kept growing until the farm was ready to harvest them rather than having early senescence. “It means the crop emerges perhaps one week later than the chitted seed for the same planting date.

“But by keeping the period from green leaf death either from senescence or desiccation to harvest as short as possible, which helps get full skin set, you reduce the incidence of fungal diseases that affects weight loss in store and appearance of the tubers.”

Planting at wider spacings, based on Potato Council-funded research that looked at what spacings would produce the greatest marketable yield for a variety at a given size distribution, has also helped him produce more larger tubers, along with paying attention to the CUF research into planting chronological young seed, which also has the effect of producing larger tubers.

“The result is that while our freshweight yields haven’t improved that much over time, although we probably are more consistent, we now produce 42-45% in the over-65mm fraction compared with 33% in the early 1990s.”