Hand hoeing is one of the most labour intensive and expensive jobs for large scale lettuce growers, but the latest version of Garford Machinery’s Robocrop hoe with its camera based guidance system can completely replace hand weeding.
Robocrop hoes have been available since 2001 and are used by many vegetable and salad crop growers. A camera mounted on the front of the hoe produces images that are analysed by a computer to identify the rows of crop plants, and this information is used by the guidance system to steer the hoe blades between the rows, leaving the weeds growing in the rows to be dealt with by hand hoeing.
On the latest version of the Robocrop the image analysis also identifies the precise position of each crop plant, allowing an extra set of crescent shaped blades to work down the rows controlling weed growth between the plants. Nick Tillett of Tillett and Hague Technology, the Silsoe-based research company that developed the new guidance system with financial support from Defra and the Horticultural Development Council, says prototype versions of the new hoe have given high levels of weed control in crops ranging from brassicas spaced at 50cm to celery grown at a nominal 20cm.
The front-mounted machine has individual adjustment of the hydraulically powered in-the-row blades, which are usually set at about one cm working depth. Work rates are about 3.6km/hr in brassicas, but slower in crops with closer plant spacing.
Development work on the hoe was completed in July and Garford Machinery expects to sell a limited number of the new Robohoes for use next year and is talking to a number of potential customers. The price estimate for the four-row version is about £38,000, and this compares with typical hand-hoeing costs of £400/ha upwards in salad crops and between £45 and £60/ha for spraying with the special herbicides available for weed control in brassicas.
Another high-tech approach to cutting labour costs is offered by a new UK designed fully automatic transplanter from Richard Pearson Ltd. Development work started six years ago, and there are now three prototype machines, one of them a three-row version planting tomatoes for the processing trade in California and the others are planting brassicas in Lincolnshire. The first production versions should be available next year.
The brassica versions have five planting heads with 24in row spacing. The planting mechanism is computer controlled and work rates for each head are up to 3.5 plants per second, equivalent to about three acres per hour. The planter works with standard trays of plants in plugs, and the labour requirement is one person to replace empty trays plus the tractor driver. Philip Bosworth, sales and marketing manager, says reliability has been one of the top priorities during the development programme and both the reliability and the work rate targets have been fully met. One of the five-row machines planted 1,500 acres in 2006, increasing to 2000 acres this year, he said.
A tractor of about 120hp is needed to power the transplanters, which are semi-mounted, and the five-row brassica version weighs about 2.5 tonnes. Electric power is needed to operate the transplanter’s electronic equipment, and this comes from a generator carried on the tractor’s front linkage and driven by a front p-t-o. The price is likely to be about £200,000 for the brassica version, including the generator, and machines will also be available for planting lettuce and baby leaf crops.
Another planter development comes from the Regero range with the addition of a new version offering closer row spacing. The machine is based on the standard Regero design with pneumatic operation and computer operated planting units that are said to be easy to adjust. The planter is usually operated as a single-bed machine, but there is increasing interest from the big-acreage growers in the high output triple-bed version, says Geof Wright of Regero importer, Tony Deptford Marketing.
The new version can operate with a 15cm or 6in row spacing, which will suit the needs of lettuce growers who need high density planting for varieties such as Little Gem, Wright explained. Increasing the plant population helps to produce the more compact plant size that some customers prefer. The price of a single-bed four-row planter is about £21,000.
Salmac offers a wide range of equipment for growers including the Italian built Ferrari transplanters. Recent additions to the list of Ferrari models include the Multipla series of planting modules, which features a double carousel designed to enable each operator to plant two rows at the same time. Output per operator is said to be 3,500 plants per hour or 1,750 in each of the two rows. Row spacing can be varied between 38 and 50cm, with adjustment in two cm steps, and the standard specification includes 15 to 57cm plant spacing in the row, with from eight to 105cm available as an option. Also on the options list are an area recorder and applicators for fertiliser and microgranules.
Another machinery range available from Salmac is made by Ortomec, said to be the market leader in Europe for harvesting machines for baby leaf, salad crops and some types of herbs. Salmac has recently sold two of the big TR series harvesters, in both cases with the optional shaker table attachment, and they are also offering the FM self-propelled harvester, a recent addition to the Ortomec range. The FM is available in a range of widths from 100 to 150cm, with 10cm increments, and the power unit is a single-cylinder diesel engine. The transmission is hydrostatic to give infinitely variable adjustment of the travel speed and the main driving controls are operated by a joystick lever.
There are two versions of the Simon harvester for baby leaves, the RJBAAC self-propelled model which is already established in the UK, plus a tractor-powered model that the UK distributor, Standen Engineering, is to introduce for the first time. Both versions have a similar band type cutting mechanism, but the absence of a transmission and engine reduces the price of the tractor model, making it more attractive for growers who lack the acreage to justify the self-propelled harvester.
The tractor-powered harvester is linkage mounted and is available as a single bed machine with the choice of 1.15, 1.35 and 1.55m working widths. The specification includes hydraulic adjustment of the cutting height using a joystick type control lever in the tractor cab, and there is a platform to carry small boxes. The minimum tractor size is 50hp and the list price is about £12,500 compared to around £35,000 for the full-spec self-propelled version.
In spite of the popularity of transplanters for lettuce and brassicas, precision seed drills are still widely used for some leafy crops including spinach. One of the biggest drills of this type is a triple-bed machine supplied by Stanhay to a large scale spinach grower. Nick Muller of Stanhay said the drill was based on their Singulaire series, but was built to the customer’s specification. It sows nine rows per bed with three lines of seed in each row.
This was the first drill of its type supplied by Stanhay, and although the number of growers who could justify a three-bed precision seeder is not large, Muller believes there will be a niche market in the UK and overseas for further triple drills.
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