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Seed Meters Get More Precise

The seed and fertilizer placement accuracy you get from today’s airseeders has contributed to increased yield expectations. But placement is only one part of the story. Getting the correct volume of seed in the ground is the other.

Here’s a head-to-head look at what the major manufacturers are currently using for metering systems. As the engineering represented by these designs proves, companies are applying innovation to every aspect of their machines to try and meet producers’ needs.

Here’s a look at what is currently on the market, listed in alphabetical order. This is impressive stuff. Also impressive is the fact that many of these companies call the Canadian Prairies home. That means much of this seeding innovation is home grown.


Bourgault’s PDM Plus metering system uses a finely-pitched auger to draw seed from a large, flow-through sump. Seed flows through a matched metering orifice into the sump where the polyethylene metering auger is housed. The company claims the auger is designed for long life, low maintenance and minimal residue build up. Steel augers are optional for higher abrasion products or conditions. The pitch of the auger increases as the seed is carried toward the product transfer line.

Bourgault says independent evaluation of this system confirms the company’s claim of high accuracy, even with fine seeds. It can safely handle delicate seed. An added advantage is the sump can easily be opened for unobstructed tank clean-out and metering auger inspection.

The single point sump ensures that accurate and consistent metering is maintained even when product levels in the seed and fertilizer tanks are low because there is no need to spread product over a bank of metering rollers.

PDM Plus handles a wide range of possible seeding rates, meaning farmers typically never have to change augers when changing product types. And the system is compatible with variable rate technology (VRT). Bourgault has partnered with Topcon to provide a VRT system that is available with several options and can handle full rate control of up to five different products using prescription maps.


Case IH’s Precision Air Carts and New Holland’s P1000-series carts use a roller metering system with four different interchangeable rollers available for dispensing extra fine to extra course seed and granular sizes. A separate drive gear arrangement is available for each roller. The rollers dispense product into a maximum of eight primary lines.

The metering system is available in mechanical or variable rate drive, which can be controlled from the cab using an electric clutch with a simple slide control for rate adjustment. The hydraulically-assisted rate controller uses Case IH’s AFS Pro 600 or AFS 200 display, which is ISO 11783 compliant. The New Holland version

A significant departure from the more common roller designs, Bourgault’s auger-style meter is accurate enough for even small-seeded crops.

uses the IntelliView II and IntelliView Plus II.

The monitoring systems include a set of sensors to help the operator keep an eye on the cart’s systems, They monitor bin levels, fan speed and the rate of product metered out per acre, as well as other functions. The carts can meter product in either a single or double-shoot application.


John Deere’s 1910 commodity cart uses a cartridge metering system. The cartridge, which contains the metering rollers, can be removed to change rollers even with product remaining in the tank.

Deere has incorporated a half-width disconnect into the meter, so you can manually shut off flow to half the system. It also allows the tanks to be emptied with the meter and primary manifold still in place.

The system is available with four interchangeable metering rollers which can accommodate seeding rates ranging from two to 265 pounds of product per acre. Each roller is colour coded for quick identification.

All of the cart’s functions can be monitored and controlled through Deere’s SeedStar 2 system, which operates in conjunction with Deere’s GS2 2600 display screen. This integrated system can increase or decrease seeding rate on the go from the tractor cab, along with keeping the operator updated with a wide range of info on things like fan speed, ground speed, bin levels and GPS mapping functions.

Initial air cart set up can also be done directly from the tractor cab through the SeedStar 2 system.


Meters on Morris’s 8-series XL air carts use spiral-fluted meter wheels, which eliminate pulsing and uneven product flow at low seeding rates — problems that can occur with straight-fluted wheels. A two-speed “Posi-Drive” transmission runs the metering wheels, improving performance when handling low seeding rates and small-seeded crops such as canola.

Seed plates are used for alternating between fine, medium and coarse seeds, which eliminates the need to change metering wheels for different products. Slide gates allow access to metering wheels even with product in the tanks. And product can be diverted into either air stream for single or double-shoot applications.

Morris offers an electric-over-hydraulic variable-rate metering system for their air carts as well. Like Bourgault, Morris turned to Topcon as a technology provider for precision seeding applications. The Topcon system includes a colour, touch-screen monitor that helps you build your own variable rate maps or load prescription fertilizer maps developed by consultants.

These maps allow for automatic applications of variable-rate fertilizer in conjunction with GPS. The Topcon system can control rates for up to five products at any one time, including NH3 or liquid fertilizer.


Seed Hawk’s system uses stainless steel meters for reduced wear and resistance to fertilizer corrosion. The meters divide product into six or eight 2.5-inch stainless steel lines below the metering body, eliminating the need for primary distribution heads on the drill and improving accuracy while minimizing seed damage. Seed or fertilizer can be put in any tank compartment and directed to either the seed or fertilizer knife.

Seed Hawk’s spiral roller and gearbox combination comes standard on all air tank models. The gearbox eliminates the need to change meter rollers for most products. The spiral roller provides immediate delivery of product to the air stream on start up eliminating skips in the field.

On-the-go rate adjustment is standard on all tanks, allowing for variable-rate application of seed and fertilizer with the optional Viper Pro monitoring package upgrade.

Seed Hawk’s system also offers Sectional Control Technology (SCT), which works in conjunction with a Raven GPS package. It maps the field during seeding and automatically shuts off sections of the meters when that section of the drill is moving over an area that is already seeded. It also lifts openers of corresponding sections of the airdrill so the seedbed for previously seeded ground is undistrubed.

The company says SCT allows farmers to minimize overlaps, saving up to 15 per cent on input costs. To make SCT work, each compartment of the air cart has a meter with eight sections fed by a common roller. Each section of the meter roller drops product into an air stream leading to the toolbar. A hydraulically-controlled gate over each section of the meter roller controls product flow. These gates start and stop the flow of product to the corresponding section of the seeding tool. The field map created in the Raven Viper Console automatically controls the gates.


SeedMaster uses individual row metering. Rollers inside the metering body place seed into a line that takes it directly to the opener, without passing through a splitter. That minimizes the chance of seed damage, and it also minimizes the amount of air required to deliver product.

Currently, there are three different roller options available to match different seed sizes. However, the company is developing specialty rollers that will further improve accuracy when metering a variety of different seed types. SeedMaster is also field-testing a seed singulation arrangement capable of dropping individual seeds into the air stream for precisely establishing plant populations in a field.

Metering rollers can be driven hydraulically, electrically or by a manual override ground-drive system. Rollers can be removed for repair or replacement even with product in the tank.

A feature called Zone Command can stop the flow of product to a section, or series of sections, of the toolbar to minimize overlaps. A series of electric clutches controls each metering roller section, which can be turned off manually or controlled automatically by a compatible GPS system.

Scott Garvey specializes in writing about tractors and farm machinery technology for publications in Canada and Great Britain. He’s also a former affiliate member of the Society of Automotive Engineers (SAE). He farms near Moosomin, Sask.

About the author


Scott Garvey

Scott Garvey is a freelance writer and video producer. He is also the former machinery editor at Grainews.



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