Field Notes

Seeds Are Being Asked to Land With Intention

A tire maker's planter patent argues that rubber closing wheels fail, and the steel-spike aftermarket it entered has been patented since 1906.

Clay-diorama editorial illustration of seeds being placed into furrows.

What changes in this design

A reader might otherwise picture seed depositing with a simple turning round part whose sharp pieces point straight out from its edge.

Here, the sharp pieces on the outer edge are set at an angle relative to the invisible center line that the round part turns around.

The angle is the detail to notice in the illustration. It shows that the focus is not only on having pointed pieces, but on their direction. The result of that direction is not stated.

A slot in the ground, closed badly

Picture the back of a corn planter. A steel disc cuts a narrow slot in the field, a tube drops a seed into the bottom of it, and two wheels running behind press the walls of that slot back together. On most planters as they leave the factory, those last two wheels are rubber. In dry ground they work fine. In wet ground with clay in it, they smear the sidewall instead of crumbling it, and the slot stays open. The seed sits in an air pocket. It comes up late, or thin, or not at all.

Farmers have been bolting other companies' wheels onto their planters to fix this for decades. That aftermarket is where I think this filing lands.

A tire maker files against its own material

On February 15, 2024, The Carlstar Group filed an application called Articles and Methods for Depositing Seeds. Carlstar made tires and wheels for ATVs, mowers and golf carts. The claim is narrow and mechanical. It covers a spiked closing wheel on which at least one tooth leaves the outer surface at an angle to the plane perpendicular to the wheel's axis. Teeth that lean, so they rake soil sideways into the slot instead of only punching holes in it.

What caught me was the background. To argue for steel spikes, the company had to write the case against rubber, and it did: rubber closing wheels, it says, are generally not able to satisfactorily close the furrow, leaving seeds exposed in many scenarios. A tire manufacturer put that sentence in a public document.

Two weeks later, on February 29, Carlstar was sold to Titan International for about $296 million, $127 million of it cash and the rest in stock. The announcement described what it was buying as products used primarily by consumers. Planter parts were not mentioned.

Angled teeth were patented in 2019

Tilting the teeth is not a new thought, and the record on that is unusually clear to me. A planter attachment maker, Yetter Manufacturing, filed in July 2016 and was granted in November 2019 on a closing wheel with multi-faceted teeth whose faces sit roughly 30 to 45 degrees off the wheel's centerline, raking soil inward. Its cited references run back to 1947.

It gets older. An independent inventor in Ontario holds a 2021 patent on a second closing wheel set at about a five degree pitch to pinch soil back over the seed, and his citations reach a filing from 1906. A university extension factsheet from 2017 counted around a dozen competing closers already on sale, from about $70 to $250 a row. This is a small, old, heavily papered corner of farming.

Five bushels other researchers cannot find

The number that sells these wheels is about five bushels of corn an acre, plus two and a half bushels of soybeans, from a large private on-farm research program.

Independent work is, to my eye, thinner than that number suggests. A 2015 study at a land-grant university in Iowa found aftermarket closing wheels made no difference to final plant stands, in conventional or no-till fields. Multi-year Wisconsin trials found roughly a two percent emergence increase under no-till and concluded the benefit depends on soil conditions. A cotton study found closing wheel type had no effect on emergence ten days after planting. For soybeans, there is essentially no peer-reviewed evidence either way.

The extension sheet also complicates the filing's premise. Rubber wheels work best in dry soil, it says, while spiked wheels are much more effective as moisture rises, especially in high-clay ground. Rubber doesn't fail generally. It fails in particular weather.

The part worth watching

These wheels are not a paper idea. A farm parts catalog already lists six of the company's spiked closing wheel kits for one major planter line, in a polymer-ring version and an all-cast version, a hedge between the rubber it knew and the steel it was patenting.

What I would watch is the timing. Under new ownership the business was renamed and folded into a consumer segment, and in the first quarter of 2025 that segment's sales nearly doubled, to $149.7 million, while the agricultural segment fell 17.5 percent and earthmoving fell 13.3 percent on lower farm income and higher financing costs. Federal figures also show the no-till acreage that created this category has leveled off in most crops.

So a new patent enters a crowded aftermarket, on a mechanism close to one already granted, carrying a headline yield claim that independent trials keep failing to reproduce, aimed at a contracting equipment market. The test I care about isn't whether the wheels work. It's whether anyone outside the company publishes three straight years saying so.

Sources

Reporting for this piece drew on the published filing and the references below.

The record, briefly. US20260231849A1, “Articles and Methods for Depositing Seeds” The abstract describes a spiked closing wheel whose outward teeth include an angled orientation relative to the wheel's rotation axis.

More angles on this

The Seed Method's Extremely Serious Fresh StartAnother reading from the same A01C classification family, planting; sowing; fertilising.
A Seed Meter With a Tiny Sense of TheaterAnother reading from the same A01C classification family, planting; sowing; fertilising.
CPC A01C: Planting; sowing; fertilisingThe official classification family this record was filed into, published in the USPTO Cooperative Patent Classification scheme.
The Leveling Bar Has a Very Firm Opinion About LevelAnother reading from the neighbouring A01B classification family, soil working in agriculture or forestry.
Confectionery, Seen Through the Eyes of a Tiny MuseumAnother reading from the wider A23G classification family, cocoa.

Read around this one:Public patent record USPTO published figure Patent issue-date index