7 November 1998


Much huffing and puffing through tubes this month as Kuhns 2224 air spreader is examined by users in Cambridgeshire and Hertfordshire. Andrew Pearce passes on their thoughts.

IF fertiliser has to be spread at 24m, its better to place the stuff where needed rather than cast it on the breeze. So reckon the farms we visited for this Hands-On Test, both of which chose the biggest of Kuhns Aero range for the job.

Wallington Farms have 1,214ha (3,000 acres) of arable land controlled by two managers. Peter Wilsons beat centres on Bury Farm, Wallington, near Baldock, which is base to the firms 30-months-old Aero and its operator James McNally. Cereals, rape, beans, linseed and hemp all receive blessing from a 1,700-litre Aero, which is carried over rolling land by a 6600 John Deere. Soils are chalk with a sprinkling of heavy clays. Why did Mr Wilson opt for the Kuhn?

"Wed had two 12m versions which had been good – those and the local dealer were the main reasons. We did consider other makes but this looked the best for us."

Further up the A1 is St Neots, and alongside that the village of Staploe. Here Peter Squire farms 647ha (1,600 acres), growing cereals pulses, rape and a little sugar beet on undulating chalky boulder clays. The business runs four MB-tracs, with operator David Nobles using an MB 1000 to lug the firms 18-month, 24m, 1,500-litre Aero.

"Weve never been able to set a disc machine so it spreads reliably to 24m," explains Mr Squire. "So we prefer a boom spreader. Its vital to get the right quantity of material to the right place, particularly with milling wheats and malting barleys. Not only does a boom spreader do that properly, but it also lets us buy less good quality fertiliser to help defray machine cost. And booms allow us to work in spring weather when a disc machine would have to stop."

As usual the operators – Messrs McNally and Nobles – field questions on day-to-day life with the machines, both of which carry Kuhns Quantron computer control system. With slope to work on, how do their tractors handle a full spreader, and what sort of work rates are achieved?

"Theres no problem with our 110hp Deere, either for power or stability," confirmed Wallington Farms Mr McNally. "Though it needs a full set of front weight on the snowplough brackets, especially when the booms are folded behind the hopper for transport. We have hopper extensions, so (depending on material) can put 30cwt in an empty spreader.

"Although thats not really enough – a spreader with this potential output should carry more – we can work fast. In a good 12-hour day with reasonable fields and loader back-up, well travel at 11-13km/hour and cover 121ha."

Mr Nobles likes to run at 10km/hour where he can. Filling from 1t bags and using his MB-tracs secondary hopper, he has covered an exceptional 162ha (400 acres) in a long day. More normally though, the target is 101-121ha (250-300 acres). "Our 100hp MB is okay for power, even with the extra 1t hopper on the load platform and a concrete-filled barrel on the front linkage to keep the outfit level," he confirms.

Theres no man platform on the Aero. But both operators need hopper access to break lumps, prompting Mr McNally to add his own step and Mr Nobles to build a platform alongside the MBs load area. Once in the hopper, grids are reckoned stout enough.

Oil drives all the major Aeros functions – a pto pump and motor for the horizontally-mounted fan, constant flow through a spool for the metering rollers. Speed control for the latter is clever, with the Quantron computer taking speed information from the tractor (either by shaft sensor or direct) and then varying a flow valve to hold fertiliser rate proportional to forward speed.

So there are oil and electrical connections to be made when hitching-on. No worries, said users – just be sure to put the pto pump on before the lift arms, or there wont be much room for the job. Mr Nobles is best-placed here, thanks to easier access past the MBs small rear wheels.

Narrow width

For narrower transport width the folded booms can be swung behind the hopper. A good idea, said operators: "But find some flat ground, as swinging them in on a slope sorts the men from the boys," says Mr McNally. Roadwork then only needs care with overhanging trees.

Computer rate control means a different approach to calibration. No more printed tables and cranking handles: instead punch in the required rate, run one of the four feed rollers (one is for each boom section) until a Kuhn-supplied bucket is full, then weigh the result and key it in. Quantron knows how many times the feed roller has turned to deliver that weight, so can work out roller speed for the required rate.

What do operators make of this approach? "Very simple once youre used to it," sums up the response, though handbook help rated only average or below. Both men agree the job takes no more than five minutes, and find that this speed makes it painless to calibrate every time the fertiliser or weather changes. "Just make sure the machine is completely emptied between materials," says Mr McNally, who, to be sure, likes to run the process twice each time.

Is the target rate held after calibration? "Yes, you can rely on it," he confirms. His opposite number agreed but when the weather is changing still likes to check calibration at midday – "More as a precaution than a necessity."

Once set up, the Quantron system lets a user store the calibration or switch between up to three pre-entered application rates for that material. And change rate in operator-set steps on the move, a facility which Mr Nobles finds very useful when crossing old hedge lines or any areas likely to benefit from a bit more or a bit less fertiliser.

But the biggest benefit, reported operators, is the way rate is tied to forward speed. "Thats a big plus, particularly if youre slow bringing engine speed up after a headland or the tractor is slow to pull away from a tight corner," pointed out Mr Nobles. Neither operator could find any disadvantage to computer control, given that manual operation is available should the magic box fail to compute. This lets the Aero be used like a conventional spreader without speed/rate compensation.

On arrival at the field, boom unfolding takes around three minutes. Neither man reckoned this too slow, preferring steady action to possible damage. And both pointed out the sense behind Kuhns boom latches, which protect against accident by locking the booms in place and simultaneously isolating the unfolding rams.

In work, the four boom sections are switched from a control box that users rated as simple to use and to understand. There is some lag while tubes empty and fill, but its something easily allowed for, they say. Angled headlands are driven as with a sprayer, flicking section shut-off switches as needed.

Top and bottom hopper windows show whats in reserve as work progresses. Or they do to Mr McNally, who would like them deeper – "With a 24m spread on long work it would be better to have earlier warning." Mr Nobles cant see hopper level thanks to the second reservoir on his MB-trac, so he uses Quantrons built-in beeper. This squawks when a pre-set weight remains. "You need to be careful as the alarm is activated by calculation, rather than direct contents measurement," he warns, "but its never let me down yet."

Both farms buy fertiliser from a range of sources according to price. So quality varies; how does the Aero cope? "The hopper can bridge with dusty imported nitrogen," says Mr Nobles, "Especially on early mornings when the air is damp." Mr McNally hadnt been troubled by bridging, but like his counterpart found that damp dust from prilled urea and lower-quality ammonium nitrate can build up, particularly in the boom collection cups and on the deflector plates. A problem shows up as visibly falling output from one or more boom outlets and theres only one solution, said users – cleaning every hour or so.

Other than the above, users felt that damp has little effect on performance.

Staying with blockage, Mr McNally pointed out a potential Aero shortcoming. "We find that the fans inlet grille blocks too easily, mainly with leaves from rape or wheat in its later growth stages; and for the same reason we cant use it on chopped straw at all. The fan should be moved to somewhere higher or its inlet point changed." Now for any boom machines trump card – the ability to work in wind. "Weve often used the Aero when you wouldnt go with a twin disc," smiles Mr McNally: "Once when it was blowing hard enough to rattle asbestos sheeting on the barns, and we still didnt get any stripes." Mr Nobles agreed: "Weve spread in a near-gale and havent seen any effect at all. You cant fault it, even though the deflectors toss material into the air."

Cleaning out was reported easy, thanks to feed rollers that can be swung aside for hopper emptying and a lack material-trapping nooks and crannies. Daily maintenance also scored well: the Aero needs attention to a few grease points, its fan drive oil reservoir checked and an eye kept on boom cable tension. But, says Mr Nobles, topping up that reservoir through a normal funnel after a filter change is very awkward.

How about reliability? Between them the two Kuhns have so far covered around 9,991ha (24,500 acres). The Wallington Farms example has been stopped once by computer failure, though it carried on in manual mode. Operator Mr McNally has changed several of the fan outlet chambers rubber block mountings, reporting that when these fail, housings on that boom half dont line up so air pressure falls. The Staploe machine has lost a metering drive cover mounting, but has otherwise been fault-free.

To close, heres how users and management sum up the Aero experience to date. From Wallington Farms: "Theres room for improvement, particularly to the fan inlet. But its a very good machine – very accurate." And from the Staploe team: "Were very pleased with it. Accuracy is a lot better than the twin disc machine we had before and we can work in a lot more wind."

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