Planter Technology

Planting and fertilizing a crop is a critical and highly technical endeavor. Each crop has its own requirements. Corn kernels are a different size from soybean seeds or wheat seeds or any other seed. Even seeds within a species will be differently sized. Each needs to be planted at a specific depth below the soil with a specific mixture of fertilizer in precise locations and with a specific distance away from other seeds so the germinating plant can use the nutrients.

Planter Technology

In recent years, one conservation tillage system asks the farmer to plant each seed directly into the stubble left over from last year’s plant – one seed into one stubble hill from last year’s plant. That requires a lot of precision.

With small seeds like wheat the planters are known as drills, the rows are much closer together, the seeds are planted much closer and the furrows are shallower. But the need for precision is no less.

In addition, planting decisions have to be integrated with cultivation, pest control and harvesting decisions. What the farmer does in the spring planting season affects the rest of his or her year. It’s no wonder there has been so much research into planter technology and why there are competing machines available.

There are really only a few basic functions that a planter needs to accomplish –

  • The planter needs to open up a furrow in the field at a precise depth. In a minimum tillage field, this is made more difficult by the stubble that’s left on the field from last year’s crop, and so minimum-till planters will have blades in the front to cut through some of the stubble.
  • Seeds need to be selected from a bulk hopper and delivered into the furrow at precise distances from each other. This is the metering system, and each manufacturer boasts about their accuracy.
  • Most modern planters offer systems to apply either liquid or granular fertilizers at the same time as the seeds. These systems require their own metering systems.
  • Finally, the furrows need to be closed, covering the seeds.

On the surface it seems like a simple process, but the devil is in the details.

Like everything else in agricultural technology, planters are getting bigger. In the late 2000s, John Deere came out with a corn planter that can plant 48 rows spaced 30 inches across – so, when the planter is spread out across the field it has a wing span of 120 feet. In the past, each of those rows had its own seed box and fed seeds down into the seed meter by gravity. Now, most manufacturers offer bulk hoppers that use air pressure to deliver seeds to each planting head from one large container.

In planter technology, it’s not just a question of getting bigger, but also getting better at accurately placing the seeds.

In the 1920s, farmers planting corn mechanically would set out a wire over each row with knots at a given interval. The planter was hooked up to the wire and when it hit a knot a gate would open and a seed would drop. But too often more than one seed would drop.

So, later planters went to a system with a rotating disc with holes in it. The disc’s rotation was linked to the forward motion of the planter. Corn seeds would drop onto the disc and fall into the holes. The disc would rotate and then drop the seed when the disc got around to the planting position.

The most recent designs use air pressure to either blow the seeds into the holes or suck them up to the hole.

Jim Ermer (left) is the Case IH dealer in York, Nebraska, and has to special order each planter he sells. “We are operating now much more on the premise of trying to have it sold before we order it,” Jim says. “Then, we get it exactly the way he wants. The company [Case IH] doesn’t really care for it that way, but they want us to not have a boatload of inventory.”

Chris Ziegler is a grain farmer near Thayer, Nebraska, and has seen planter technology change as he grew up farming with his grandfather Clyde Ehlers. “He had one of the first 12-row planters in the area. And I remember telling somebody that Grandpa got a 12-row planter. He was like, ‘No! You didn’t count the boxes right,’” Chris says. “There are so many parts to a planter. And of all the equipment a farm needs, that planter is the most important machine out there.”

Written by Bill Ganzel, the Ganzel Group. First published in 2009. A partial bibliography of sources is here.

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