Tine for a new approach?
By Tom Allen-Stevens
Large machines are generally still required for most seeding and soil preparation. 4AR assesses the autonomous solutions and reveals a new concept which may revolutionise how seed is put to soil.
By Tom Allen-Stevens
When it comes to crop establishment, there is a fundamental issue that works against the concept that ‘small is best’ – draft force.
This is the force required either to pull a tine or share through the soil to loosen it so that a seed can be placed, or to drill the seed direct.
In both cases, the force is such it requires a fairly hefty piece of kit to penetrate most soils. This force is directly related to the weight of the vehicle used to do the pulling.
Seeding technology
So what are the options for the autonomous bot?
First off, it’s important to recognise the difference between a seeder unit that places seed into a fine tilth, and one with a tine or disc that has to penetrate the soil through a thick layer of crop residue. A number of lightweight seeders are now available, notably the Farmdroid FD20 (see Digital Delve).
Fendt’s Xaver field robot benefits from the vSet seeding technology, supplied by sister company Precision Planting, that precisely places the seed with the help of an electrically driven control system.
Fendt’s Xaver field robots precisely places the seed with the help of an electrically driven control system.
The three-wheeled bot, not yet commercially available in the UK, is designed to work in a swarm, has one coulter and a 20-litre seed tank. Precision Planting’s Smart Firmer technology is due to be installed, that measures soil moisture, temperature and a host of other variables. With a total laden weight of 250kg, it’s not yet clear whether Xaver will seed direct into stubbles.
On the heavier side, AgXeed’s AgBot 5.115T2 has an unladen weight of 7.8t and 156hp of grunt. Part-owned by Amazone, the tracked autonomous machine is claimed to accurately operate a number of the company’s drills and seeder units attached to the rear, cat 2 three-point linkage.
AgXeed’s AgBot 5.115T2
The Robotti 150D from Danish manufacturer AgroIntelli made its debut to the UK last year. Powered by two 75hp Kubota diesel engines, sat either side of its gantry, it can take a seeder unit of up to 3.33m width between them, and puts an unladen weight of 3.15t on to its four drive wheels.
Raven’s DOT platform has been rebranded to Omnipower. While the previous version delivered 173hp from a 4.5-litre Cummins diesel engine, Raven claims this has been stepped up for the Omnipower 3200, with 50% more power to the ground. The autonomous 6m, 8t frame can take a range of conventional seeding tools.
Salin 247 is a newcomer to this space, based in Iowa and benefiting from funding via Ag Startup Engine. Weighing about 1800kg, its electric drive kicks out 27hp to a range of implements including a four-row planter.
AgroIntelli’s Robotti 150D made its UK debut last year.
Coulter revolution
Those looking for a revolution in coulter technology are likely to be disappointed, however. All systems currently available or near market are based on the disc or tine coulters growers have relied on for decades. And when it comes to direct drilling, all require significant draft.
One interesting development is the AquaTill, a novel solution from Australia which fires ultra high-pressure water jets onto the soil surface at mach 3 which cuts through all manner of trash and cover into the seeding layer.
As well as cutting through up to 35t/ha of trash, it loosens the soil below, creating what’s claimed as a perfect, onion-shaped bowl for a following tine or disc coulter to drop in the seed. You need 120-450 l/ha of water, depending on trash volume and row width, and starter fertiliser can be applied at the same time.
Other low-draft seed-delivery mechanisms are still at concept stage. One idea is a drum punch seed planter. This comprises a rotary drum with a series of J-shaped punch tools on its outer perimeter. Fixed to the inside of the drum are cups that feed the seed from a central metering system down into the bottom of the J.
Drum Punch Seed Planter
Designed primarily to work through plastic mulch, the drum is pulled over the soil surface, with the feet punching through, cupping the seed in the J on the way in and leaving it in the soil to the correct depth on the way out.
The ISOT progression
There is one concept that’s progressed quite a bit further, however. Innovative Soil Opener Technology (ISOT) has been developed over the past decade or so by Rob Borland. Born and brought up in Zimbabwe, his father was involved in introducing zero-tillage systems to farmers in southern Africa.
For the past 20 years, Rob’s lived in the UK, pursuing a career in mechanical engineering, including working for JCB and Caterpillar. As and when time and funding have allowed, he’s also developed ISOT, working with Cranfield University. Now he plans to work with the Small Robot Company to bring the first truly low-draft direct seeder to UK farms.
“What makes the ISOT different is that it has a reciprocating action to penetrate the soil,” explains Rob. “At any one time there isn’t much of the planting mechanism engaged in the soil and that significantly reduces the draft requirement.”
The prototype opener centres around two chisel-shaped tines, each mounted on an arm with a rotating cam so that they oscillate up and down in a sinusoidal motion. The downwards stroke penetrates the soil with the seed timed to drop through a tube fixed to the back of the tine.
“The tine creates a space for the seed but doesn’t stay in the ground. That reduces the force required and also ensures surface trash isn’t a problem,” notes Rob.
The cam can also be adjusted to precisely time the tines, so that even with several openers in series, only one or two tines would be penetrating the soil at any point in time. That means a large downward force isn’t required, so the ISOT can be fitted to a light-weight autonomous robot, he points out.
“In fact, you can drop the weight requirement by 95%. You only need enough to keep it steady.”
Overall draft force required is reduced by 75%, compared with current zero-tillage technology. The prototype indicates the overall power requirement is reduced by 15%, although Rob believes further development of the concept will significantly reduce this further.
Innovative Soil Opener Technology (ISOT) has been developed over the past decade or so by Rob Borland.
As well as handling trash well, the design is suited to all soil types, including stone and brash, he claims, and will work in ploughed as well as zero-tillage situations.
There are challenges to overcome, however, particularly the depth – at present the protype deposits seed at about 15mm depth, while cereal seed needs to be planted at least 25mm below the finished surface.
Dropping seed down tubes that are oscillating rapidly is also a bit of a problem, while zero-till purists may feel the reciprocating action on the soil surface is too much disturbance. Although the disturbance is a lot less than a tined or disc drill.
Rob plans to work closely with the growers in SRC’s Farmer Advisory Group to refine the design, with a view to getting a new working prototype in the field by autumn 2023.
“A lot will depend on demand and interest from farmers, but I’ve been buoyed up by the enthusiasm we’ve received so far,” he notes.
One farmer who’s already seen the prototype in action is FAG member George Renner at Normanton Lodge in Rutland. Rob tried it out on the farm’s limestone brash, direct into stubble with chopped straw in December 2021.
“It is a novel approach, but struggled a bit in the very challenging conditions we gave it,” reports George. “I can see there will have to be quite a few modifications before you achieve a system that you can apply in practice, and at the moment it seems it would work better for small seeds.
“But the beauty of the design is the minimal draft requirement, compared with current seeding technology. I’m looking forward to seeing how it develops.”
