Imagine a planter that can work up to 50% faster, achieves top-rate singulation and in-row spacing, works from prescription maps to vary plant population, and stops and starts planting at headlands – even on an angle – with uncanny precision.
Then imagine a planter that can select different varieties for different zones across the field to provide optimum traits for different situations and you have a picture in your head of the ultimate course of precision planting technology.
The catalyst for all these advances is the switch from mechanical planter unit drives to neater and simpler electric motor drives – in combination with some radical thinking on seed metering and delivery mechanisms.
Add global navigation satellite system-based implement control, and the biggest advances in planter technology since the invention of the vacuum metering wheel are now available to growers of soya beans, corn, sunflowers and similar crops.
Being confined to a modest 6-8kph (4-5mph) working speed is no longer a restriction on the latest precision planters. With the ability to work at 12-15kph (7-9mph) and more in good conditions, growers can gain significantly increased capacity without going wider.
It’s one way to buy greater seasonal capacity to cope with a larger acreage or to save operating costs by reducing from, say, 3 planting outfits to just 2. Alternatively, says Cory Muhlbauer, R&D agronomist at equipment manufacturer Precision Planting, the increased sowing capacity that comes from faster working speeds can be used strategically to hit optimum sowing conditions.
“Our SpeedTube allows farmers to increase their planting speed to as much as 16kph (10mph) and use that 50% increase in productivity to take advantage of a planting window when conditions provide the best opportunity for germination,” he points out.
“Growers don’t have to push the conditions, as far as wet or dry soil or colder environments are concerned; they can wait for the perfect time to optimise germination.” The SpeedTube replaces simple gravity delivery of seed into the furrow with a miniature flighted conveyor belt, so there is none of the ricochet that can occur within a vibrating tube.
Moreover, the belt discharges the seed at a shallow angle and at a velocity that automatically matches the forward speed of the planter, minimising any risk of spacing displacement through seed bounce as it lands in the furrow. The belt, together with the 2 feed rollers that supply it, are driven electrically and the SpeedTube can be fitted to new or existing planters.
Vacuum seed metering is turned on its head in the new-generation Amazone EDX, Lemken Azurit and Väderstad Tempo planters, as they use air pressure to select and hold seed against perforations.
Each seed is released into the seed tube when a small wheel on the other side if the perforation blocks the airflow and is then propelled by air to the furrow, where it is captured beneath a soft press wheel to prevent bouncing and ensure intimate seed-to-soil contact.
While the singling process is performed on otherwise conventional row units on the Azurit and Tempo planters, the Amazone EDX design uses a stainless steel drum located beneath the bulk seed hopper.
Perforations punched in lines select the seed, which is blown down narrow plastic tubes to the row units, which in common with many other planters, are designed to handle conventionally cultivated, min-till and no-till surfaces.
Amazone says its EDX precision planters can achieve work rates 30-50% greater than a conventional seederm, thanks largely to working speeds up to 15kph (9mph), but also because of features designed to make them easier to set-up and quicker to refill.
A 6m mounted version is said to be good for 400ha to 700ha (990-1,730 acres), a trailed planter of the same size 900ha (2,200 acres); a workload of up to 1,500ha (3,700 acres) is within the 9m EDX’s capabilities.
Of its Gilstrand metering system, Väderstad says in laboratory tests, very low levels of misses and doubles were recorded as ground speed approached 17kph (11mph), in contrast to the rapid deterioration seen with conventional planters. Speeds up to 15kph (9mph) are recommended in the field.
While hydraulic drive to a bank of conventional planting units can be used to provide manual variable seed rates or auto control from a prescription map, individual electric drive of the metering mechanism has many more possibilities.
Peter Bixel, a grower and SciMax Solutions agronomy leader at the MaxYield co-operative in northern Iowa, US, is an advocate of seed rate tuning. “We’re advising on half a million acres of variable rate planting; even though we’re pretty flat here there’s enough variability in the soils to justify it,” he says.
With corn, seed rate is typically trimmed on less productive land to give individual plants more space to perform and gain yield, while increasing plant population exploits the greater yield-supporting potential of better soils.
“The opposite is true for soya beans because on better soils we don’t need as much seed to achieve a good final stand and yield, while increasing seed rate on lighter land achieves greater foliage cover to help conserve moisture and raise seed yield,” says Mr Bixel.
Kverneland was among the first manufacturers to take variable rate software a step further by controlling the vacuum metering units on its Optima planter individually. Using a global navigation satellite system location input and GEOcontrol mapping software, oversowing of areas already planted is automatically avoided by stopping and starting the metering units as necessary.
Even on angled approaches, crop rows in the main body of the field neatly stop where they meet the headland rows, which can be planted last.
Apart from looking neat, this technique saves seed; field size and shape determines how much, but Kverneland says 2-8% is not uncommon. Moreover, the GEOseed feature will align the planter’s metering discs to sow in conventional rows or in a narrow row diamond pattern that gives each plant an equal amount of growing space.
Kverneland cites trials showing 30-45cm (12-17in) row spacing can result in yield increases of up to 10%, compared with traditional 75cm (29in) rows.
For growers inclined to organic production, accurate diamond planting alignment throughout the field means mechanical weeding can be performed across the rows – at 2 angles – as well as the direction the crop was planted.
Lemken has opted for a fixed staggered row pattern for the Azurit planter, with individual seeds isolated on 2 electrically-driven perforated discs offset from each other inside the pressurised metering unit. Each row is spaced 75cm (29in) apart, with the sub-row centres at 12.5cm (5in); fertiliser can be placed between the sub-rows.
This layout results in a 70% increase in the area available to each plant, points out Lemken, with the potential to more effectively utilise available light and moisture, while greater surface coverage and enhanced root development help combat erosion on susceptible soils.
Manufacturers have also exploited electric metering drive to maintain the correct seed rate as a wide drill sweeps around a curve and over contours by individually adjusting metering system output in relation to ground speed for each row.
Kinze’s Curve Compensation system requires sub-10cm (4in) level GNSS guidance, while Horsch employs radar on each end of the Maestro drill frame for its ContourFarming feature. Among others, speed-related control is also available on Agco White 9000VE and Case IH Early Riser planters equipped with Precision Planting vSet seed meters.
Without Curve Compensation, says Kinze, pulling a 24-row, 76cm (30in) planter set for a plant population of 35,000/acre through a tight curve will result in the 15cm (6in) plant spacing dropping to 7.6cm (3in) along the inside row and increasing to almost 23cm (9in) in the outermost row.
Resulting seed populations are some way above and below the target at either end of the planter across an area that may be relatively small as a proportion of a large field, but still compromises a grower’s efforts to produce the best possible crop.
The prospect of exploiting particular plant traits to tackle yield-inhibiting factors within fields has become a reality with the introduction of planting equipment that can switch between 2 seed lots.
The Kinze 4900 Multi-Hybrid planter and Precision Planting’s vSet Select twin disc metering system have 2 electrically-driven metering discs feeding a single seed tube so that different varieties or hybrids held in twin tanks can be switched instantly in response to a prescription map.
“The technology works just fine in the field,” confirms Peter Bixel of MaxYield after 2 years of trials planting corn and soya bean on clients’ fields. “The big question is how you choose the optimum variety or hybrid combination for zone planting in each field,” he adds.
“I’d like to see a lot more detailed information from the seed companies on the performance of different varieties and hybrids in different situations to help with that.”
US breeder Beck’s Hybrids claims to have more experience than most of this approach, having conducted trials for the past 6 years with a hybrid classification system designed to help selection across field landscapes.
Results from multi-hybrid planting depend upon the scale of variability, of course, but advocates see the potential for the technique in planting more drought-tolerant cultivars on hill slopes and sandy soils, or in the corners of circle-irrigated fields that get no added moisture.
Other possibilities include planting varieties chosen for robust disease resistance in field environments prone to infection or in areas where access for spraying – particularly by aircraft – is difficult.
Hybrids with a high-stress emergence rating could be planted selectively in field areas prone to poor emergence, suggest advocates, while field margins could benefit from varieties or hybrids with greater insect or weed-competition tolerance, or with herbicide-resistance traits that allow more effective control of invasive weeds.
Standing ability or maturity could be used strategically to compensate for soil and environmental factors, and some envisage selective use of seed treatments in a twin seed-planting strategy.
“In our 2015 soya bean trials, we got better yields by compensating for differences in soil-pH,” recalls Mr Bixel. “We placed a ‘defensive’ variety in high pH areas where iron chlorosis reduces yields and an offensive variety in lower pH zones.
“But seed companies need to keep gathering data and interpolating the results, so we can accurately advise clients where they should get better yields and a financial return from using this approach.”