There is a popular saying that all that differentiates a good farmer from a bad farmer is "a week". Timing can be crucial, and never more so than in the race to get fresh fruit or vegetables into store or out to market.

Picking or harvesting in this sector has long been reliant on readily available sources of seasonal labour. But a Commons library briefing reports that the NFU's seasonal labour survey for 2008 shows a staggering 61 per cent of respondents claiming to have lost income as a result of labour shortages, with 58 per cent directly due to crops that could not be harvested and had to be left to rot in the ground.

The briefing reports a further 30 per cent of losses due to crops that, because of labour shortages, were harvested too late to be saleable by the time they reached the market. The best estimate for total losses in 2008 is £8m, but that figure is expected to rise dramatically in this year

The problem is, in part, due to changes in the Seasonal Agricultural Workers Scheme (SAWS), which is due to end next year. It is also partly due to an increasing reluctance for migrating workers to take part in horticultural activities, and partly to an overall diminution in the number of migrants visiting the UK.

The upshot of this is threefold: firstly, a physical reduction in the size of the workforce; secondly, by the law of supply and demand, increased labour costs; and thirdly, a major loss of flexibility and timeliness on farm.

Mechanical solutions

While political solutions may partly resolve these problems, increasing numbers of growers are turning to sophisticated mechanisation to put themselves back into control.

Sales manager Karl Arndt of Everett Bros Engineering in Thetford, Norfolk, reports a surge of interest in mechanical solutions. Everett Bros is the UK distributor for the market-leading Asa-Lift range of harvesting machinery.

"At the moment we have many enquiries from cabbage and leek growers, looking to achieve significant savings on manpower" says Arndt. "One customer in Lancashire, for example, has reduced his traditional harvesting gang of 10 men down to four people, achieving in five to six hours the same results that previously took nine hours."

The most popular machines for harvesting cabbage are the Asa-Lift MK 1000 B or E. These are tractor-mounted models that deliver the crop to boxes (B) or via elevator (E) to a trailer.

Although both versions share a similar header, Arndt is keen to point out that no two machines are ever the same because of the high degree of flexibility in manufacturing, which allows bespoke solutions for individual growers.

At the business end, two guide cones bring cabbages, grown at 60cm rows, into the machine, allowing them to be cut by a pair of discs, fully adjustable to suit different varieties.

The crop is then transported by an auger system, which strips off the outer leaves in the case of products destined for immediate use, or transported into boxes in the MK 1000 B machine.

Machines with this degree of sophistication do not come cheap. Due to their bespoke nature there is no set price, but they generally fall into the bracket of £40,000 to £55,000. Users, however, report payback in two to three years, which - given the peace of mind achieved in a fluctuating labour market - seems a very attractive proposition.

Leeks - harvested from July right through to the following May or June - also benefit from mechanised harvest. Again, a tractor-mounted machine is causing the most enquiries - the PO 335 relies on a system where leeks are pulled up by two rubber belts and trimmed as they pass trough the system to be deposited in boxes.

Arndt is excited by the prospect of using this machine for spring onions, which are currently undergoing trials. If successful, this will result in very big savings at harvest.

With crops of 60ha and upwards, a self-propelled version of the leek harvester comes into its own.

Known as the SP100PO, this is used on quite small areas in Holland and Denmark. One has recently been sold in Ireland and feedback on performance is keenly anticipated.

High standards

While cabbage, leeks and, hopefully, spring onions occupy a great deal of interest, carrots, parsnips, red beet, turnips and chives are among many products that can also be successfully harvested to today's high standards. Again, mounted machines are most popular, with compact three-point linkage and alternative lifting sections for many different crops including carrots, onions, salads and celery.

Top-lifting or share-lifting combined with a front rubber flail-topper makes this a very flexible harvesting system.

As with the cabbage and leek harvesters, these machines can be individually built with loading facilities to suit the customer's specific needs, such as 25kg boxes, 500kg boxes or lifts.

It is easy to speculate on a variety of developments in the field of automated harvesting. Like robotic milking, the holy grail could well be to eliminate labour completely. With integrated systems from planting through to harvest based on a GPS, arguably the only hindrance to development is economics.

Problems with picking

It is, however, hard to see this argument extending to picking. Picking requires that the plant, bush or tree is left unharmed after the process, and the crop itself is at risk of damage when extracted from, often, a fairly dense canopy.

Developments in this area therefore tend to revolve around the need to optimise labour and increase the output and quality of each individual picker, rather than simply to reduce picker numbers.

A good example can be found at Haygrove, which - from its own experience as a major grower - has developed an innovative picking rig for use on crops such as strawberries and asparagus, both in tunnels and out in the field.

The Pic-King rigs grew from a unit now known as the Pic-King 1 Series, which was invented by Herefordshire strawberry grower Jeremy Price. It removes the need for manual carrying of fruit and vegetables, eliminating three runners from a team of 40 pickers. Based on UK wages, the price of the machine could be paid back in 12 weeks.

The rig is capable of carrying up to three pallets of fruit or vegetables. The Pic-King 1 has dual-position drive controls so the operator can always walk behind the machine. But the largest savings are achieved with the 5 Series rigs, used in conjunction with the 1 Series.

This rig consists of eight, 10 or 12 powered seats travelling horizontally along the beds, enabling each picker to position themselves relative to the fruit in front of them. The seats move forwards and backwards with a robust and simple belt-drive mechanism and are equipped with hydraulic height adjustments to allow pickers to be kept at the correct height, regardless of rutted alleys or varying bed heights.

Now with over 30 Pic-King harvest rigs operational, Haygrove has reported that 20 to 35 per cent more strawberries are picked compared to conventional hand-picking. Most of the benefit seems to be achieved in lifting the productivity of average or below-average pickers and managing this team of pickers to the minimum wage.

Haygrove says overall productivity is improved from 76kg/day to 104kg/day, with the poor performance of the weakest pickers vastly improved. The quality of the fruit picked also benefits.

Based on 20 weeks' use per year, Haygrove anticipates the machine will pay for itself within three seasons.

While labour savings are a great incentive to increase mechanisation, the greatest benefit seems to be the return of flexibility and control into the hands of the grower.