2 August 2002

No room for error in Jersey harvest

By Hugh Symington

WITH the UKs maincrop potato harvest looming – and all the work thats involved – it is perhaps worth sparing a thought for the Jersey potato grower where the use of correct harvesting techniques are critical if maximum returns are to be achieved.

First early potato lifting in Jersey starts at the beginning of April and prices ex-field often exceed £2000/t. But with a growing season of only 10 weeks the key to maximising profitability is attention to detail at harvest.

"There is no room for error at this critical time of year," says Jersey potato grower Nick Mourant of Haut-Dumont, St Helier. "Nothing short of total commitment to achieving the highest quality and maximum returns will do when everything hangs on such a short period."

Although timing of harvest is critical because crop prices are highest the earlier lifting starts and before marketing groups can set quota for the season, he says the lifting equipment is the key link in the chain if tuber damage is to be minimised – and income maximised. This year he says he managed to achieve zero damage reports from Jersey-based marketing group T O P Produce who comply with Tesco Natures Choice.

Mr Mourant grows 135ha (340 acres) under plastic to take advantage of an earlier start to harvest – feasibly by two weeks. Three weeks after the plastic has come off about 20% of the crop is hand picked. The entire crop is lifted as green top so when the potato yield exceeds 13t/ha and is sufficiently mature he lifts the remainder using a 2-row Grimme GZ harvester pulled by a New Holland TS 110.

"To achieve zero damage consistently is not easy," says Mr Mourant. "We have to remove all clods, stones, mis-shapes and greens from the sample. We also have procedures in place to ensure we can demonstrate full traceability – a sample is taken from every load as it leaves the field, then sampled again before and after grading."

According to head tractor driver Eric Rueb the Grimme GZs Multi-Sep unit – four pairs of adjustable contra-rotating rollers – helps to achieve good separation, but not to the extent that tuber damage occurs. The harvester is also operated with six people on the picking table.

"We often lift in difficult conditions and use 9.5in tyres because we are on 30in rows," he explains. "With these narrow tyres, a powered rear axle on the harvester is essential when working in sticky conditions if we are to keep moving. Some of our land is quite steep and automatic levelling of the separator unit also pays dividends – as does the ability to raise the rear of the machine to give increased sieve action on the main web."

Clearly a Grimme enthusiast, Mr Rueb also points out the value of the flights attached to the cascade web which prevent the crop rolling back on slopes and the use of side panels along the length of the cart elevator which enclose the potatoes within individual pockets to protect against friction damage.

"With so little time to get as much of the crop out of the ground as early as possible we cannot afford to be dictated to by the weather or ground conditions," says Mr Mourant. "The harvester needs to be capable of not only operating in all conditions – it also has to produce a good sample." &#42

Haut-Dumont operates a two-row Grimme GZpotato harvester which is claimed to be effective at separation and minimising tuber damage.