While technology contributes a lot towards greater application accuracy of fertilisers, gains can also be made by changing working practices. Geoff Ashcroft reports.
When it comes to making the most of application accuracy with crop nutrition, the choices available to growers are extensive.
The lion’s share of application continues to be carried out by twin disc spreaders, which have seen some significant strides made to them in application accuracy in recent times. With advanced electronics linked to GPS, spread pattern management has been improved to boost output without compromising on accuracy.
Similarly, those handling liquid fertilisers are equally spoilt for choice, with developments from sprayer manufacturers offering impressive levels of accuracy through individual nozzle control and auto-section control.
Whether applying solids or liquids, both have the benefit of working to variable rate application maps, and many have the ability to integrate drone technology by using aerial crop imagery to identify areas for attention.
To find out more, we caught up with several growers, all taking different routes to boost application accuracy (see panels).
One grower making the most of multi-layered application technology is Graham Potter, who has recently added a 24m/3,500 litre Mazzotti MAF3580 self-propelled sprayer to his fleet, to increase application accuracy.
“Variable rates hold the key to profitability on our farm,” says Graham Potter based at the 200ha Topcliffe Grange, near Thirsk. “We cannot afford to make blanket applications, nor can we apply sprays and fertilisers to areas where we will not see a benefit.”
In addition to individual nozzle control, Mr Potter’s Mazzotti sprayer is also fitted with the latest N sensor, allowing application management to contribute to more cost savings across the business.
Making the most of application accuracy, he also uses drones to provide an aerial view of crops. These include a DJI Phantom equipped with a second camera for NDVI imaging, and also a DJI Mavic Air. The latter is a sub-250g drone and is free of the restrictions imposed on his larger aircraft, given the farm’s location within a no-fly, Military air traffic zone.
“It takes too long to get clearance to fly the Phantom, so the smaller Mavic lets me analyse immediately with the help of the Skippy Scout app,” he says. “It can fly autonomously to any flagged in-field points that I have chosen and provide basic data that lets me create a treatment plan, through Drone Deploy.
“We only use the drone selectively, as a management tool to target immediate issues,” says Mr Potter. “And if we cannot bring up the under-performing areas of a field, we will simply take them out of production and sow bird mixes and bee mixes where cereal production just will not pay.
“Variable rate had already reduced our costs, though individual nozzle control means we are now more precise with all of our liquid applications,” he says. “Investing in precision farming systems is a long-term plan, but I believe it is the best investment a farm could make.
“More so when you consider the savings on offer from reducing overlaps, adopting variable rates and spot-treatment plans.”
Fertiliser applications by disc spreader continue to dominate the sector and advances in GPS control systems have contributed to reducing overlaps through start-stop technology. In addition, the ability to vary the spread width through automatic section control is recouping the cost of sophistication in just a few years. And this is something Hamish Stewart has found at Ragley Home Farms, Warwickshire.
With about 400 tonnes of bagged fertiliser to apply each year, farm manager Mr Stewart favours the application accuracy of his Kverneland Exacta TL with Geospread. “We tray test with SCS and buy reputable fertilisers to ensure we spread correctly at 32m.”
The 2,400ha Warwickshire estate operates across 1,600ha of arable cropping, with a mix of winter and spring cereals, plus linseed and poppies, with grass and parkland accounting for 280ha. Until six years ago, Ragley Home Farms was wholly liquid fertiliser, but the workload proved too much for just one self-propelled sprayer.
“With the introduction of an accurate fertiliser spreader, it is logical to share the workload across the farm,” he says. “While we can now spray and spread at the same time, albeit on different areas of the farm, perhaps more importantly we now apply exactly the right amount of fertiliser, and in all the right places.
“We have found that our crop canopies have evened out, and we have eliminated lodging at headlands from auto start/stop and section control,” he says. “Headlands account for 33% of the land we farm, so this area demands closer scrutiny.”
Average field size is just 6.5ha, with inputs carefully targeted using variable rate applications to suit crop and soil types. Operating efficiency is helped by a high-tip trailer, into which fertiliser bags are emptied, to speed up turn-around times when the spreader needs refilling.
“Using a trailer to fast-fill has created a huge efficiency gain,” he says. “And given the accuracy of weigh cells and RTK-guidance, we can cover around 600 acres/day, spreading at speeds of up to 20kph.”
Away from advances in technology, one Kent grower has adopted a more simplistic viewpoint, which focusses on maintaining the spreader’s working height to boost accuracy. This is because Clive Wreathall chooses to carry his fertiliser spreader on a bogie.
“We have moved away from buying technology that does not have a benefit,” says Mr Wreathall, who farms 1,200ha on Romney Marsh with his brother Andrew. “It can be a very costly exercise.”
Their rotation includes winter wheat, winter and spring barley, oilseed rape and peas. But with land on two units located around seven miles apart, the emphasis is on minimising downtime and maximising productivity.
A 40m tramline system is in place and the farm’s Hardi Alpha sprayer is used exclusively for crop protection products - all fertiliser applications continue to be applied using a twin-disc spreader. “We run a KRM Bogballe machine, but we do not carry it on the tractor’s three-point linkage,” he says. “It is pointless at this width.
“Firstly, it is very heavy and it would need a heavy tractor with ballast to maintain balance and composure,” he says. “Secondly, if we were to successfully apply over a 40m tramline width, the spreader’s discs need to sit at a perfect ride-height all the time. And to achieve that, we need to avoid influencing the spread pattern from the tractor bouncing and pitching around.
“The only way to achieve this is with a bogie system towed by the tractor,” he adds. “This means that we can also use a smaller, lighter tractor, which also helps to maintain tramline condition.”
Mr Wreathall says 130hp is all that is required, because the tractor only has to pull, not carry, the Bogballe spreader.
“The spreader now sits at the prescribed ride height all the time, no matter what the tractor does,” he says.
“There is no bouncing from the tractor, so the spread pattern is maintained. And that is important when you want to throw fertiliser over such a wide width. The smallest movement at the disc becomes amplified when you look at the outer edges of the spread pattern.”