A disc-and-pump prototype shown on 11 September in Zwartebroek, Gelderland, places liquid fertiliser directly in a crop's root zone. The machine is a working idea, not yet an autonomous robot.

Coöperatie Gelderse Vallei Kunstmestvrij ran the demo. The Dutch cooperative focuses on low-input farming. The technology is intentionally simple: a row of discs cuts a slit, and the disc shaft drives a roller pump that meters liquid fertiliser into the soil. No tractor-grade hardware required.

Herre Bartlema, chairman of the Dutch Centre for the Development of Circular Precision Fertilisation (NCOK), spoke at the event. He framed the prototype as a foundation for something larger: an electrically powered, autonomous vehicle that applies plant nutrition only when the crop needs it.

"A heavy machine is not needed for the principle shown," he told the cooperative's demo in Zwartebroek.

How does it work?

The discs do two jobs at once: cut into the soil and drive the roller pump that doses the fertiliser. Rotation and dosing are mechanically linked, so the machine cannot over-apply while stationary.

That is the kind of built-in safety a future autonomous robot will need. The setup is mechanical, not electronic — no rate controller, no flow meter in the visible chain.

The trade-off is equally obvious. To change the dose, change the gearing or the forward speed. Liquid goes in below the surface, where band placement typically beats broadcast spreading for uptake efficiency on most soil types.

Why target the root zone?

Bartlema has argued for precision fertilisation and emission reduction for years. He expects recovered nitrogen from manure processing — the EU category called renure — to deliver a large supply of fast-acting liquid plant nutrition. His catch is timing and placement. Root-zone injection addresses both.

Surface broadcasting of nitrogen is a well-documented loss pathway. Ammonia volatilisation, run-off and denitrification eat the applied nutrient before roots see it. A shallow slot below the surface cuts those losses, particularly when the liquid is timed to the crop's peak demand.

What does this change for growers?

Not much, yet. The prototype proves the dosing principle. It doesn't prove everything else a working machine will need.

• No published working width, tank capacity or forward speed.
• No dosing accuracy data across soil types.
• No self-driving capability, and no fill system on display.

Bartelma acknowledged that practical feasibility and affordability remain open questions. The dock-and-fill idea — a station that tops up the tank between bouts — exists as a sketch, not in steel. The principle is proved. The engineering, and the economics, are not.

When will it arrive?

Not this season. The next step is a self-propelled platform that carries the disc unit, then a docking station for autonomous re-filling. No telemetry, no GPS guidance, no tank-level sensor — none of that has been shown.

Coöperatie Gelderse Vallei Kunstmestvrij hasn't published a timeline, and trials on working width, capacity and dose accuracy haven't begun. Growers should treat the prototype as a proof of concept, not a product plan.

Watch the cooperative's next demo day for an autonomous prototype. Until one appears, root-zone liquid fertilisation on Dutch farms remains a working disc looking for a chassis.