C-DRONE GUIDE · 2 AUGUST 2026
Grassland biomass and grass-height estimation by drone: pastures, forage, catch crops, price
Knowing how much grass is growing, and where, changes the management of a forage system: cutting date, stocking rate, grazing rotation, forage purchases. Classic measurement — rising plate meter, cut-and-weigh — is spot-based and laborious. A drone covers the field in a few minutes, derives a grass-height model and a biomass estimate, and maps the within-field variability that the average hides. Here is what the measurement is really worth, how it is checked, and the prices observed in 2026.
Published on 2 August 2026, reviewed on 2 August 2026 — regulations in force as of August 2026.
How a drone "weighs" grass
Two families of method coexist. The first, volumetric, uses photogrammetry to build a canopy height model (the difference between the top of the grass and the reference bare soil) and converts that volume into biomass. The second relies on vegetation indices (including GNDVI) from a multispectral camera, correlated with available matter. A study by Théau, Lauzier-Hudon, Aubé and Devillers published in 2021 in PLOS ONE precisely compares these approaches on grassland: the volumetric model excels at high biomass (coefficients of determination around 0.93–0.94), while the index performs better on sparse cover (see the study on Google Scholar).
The operational lesson: choose the method by stage and objective. For an imminent cut, volumetric height prevails; for regrowth or a young catch crop, the index usefully complements it. This agronomic logic extends that of our guide to the drone in precision agriculture.
What the map adds that the average hides
The value of the drone is not only to replace a plate meter, it is to map variability. A single field carries firm zones and wet hollows, overgrazed sectors and rejects. The biomass map shows where grass is short and where it accumulates, which finely drives the grazing rotation, the paddock to open, the field to cut first, or the zone to reseed. It is decision information, not just a global figure.
On farms already tracking other drone indicators — emergence density, water stress — biomass estimation fits into the same pass and the same data flow. Value grows when the measurement becomes regular: a series of maps over the season tells the growth dynamics better than an isolated reading.
Checking the measurement: ground-truthing remains essential
An estimate is only reliable once calibrated. The biomass model is calibrated on a few reference cut-and-weigh samples in the field: it is the local relationship between volume/index and real dry matter that yields credible kilograms. Field disturbances — lodging, molehills, rejects, soiling — degrade the height model: recent literature shows these disorders weigh on accuracy and must be accounted for in interpretation. A serious provider states the uncertainty, not a figure to the gram.
Flight conditions matter too: stable light, no strong wind flattening the grass, an identifiable reference soil. The measurement is valid for comparing zones and tracking a dynamic; it does not claim laboratory-scale precision. Properly framed, it advantageously replaces dozens of plate-meter points and objectifies decisions that were until now intuitive.
Prices observed in 2026
Ranges observed in 2026 (excl. VAT):
- Biomass mapping of one field (flight, height model, map): €150 to €400 by area and access.
- Seasonal monitoring (several passes, comparable series): a declining package, often €90 to €250 per pass.
- Multi-field campaign on one holding (livestock farm, cooperative): pooled mobilisation, on quotation.
- Adding multispectral indices and cut-and-weigh calibration: extra, by number of references.
Mobilisation weighs more than area: grouping nearby fields sharply cuts the unit cost. Our precision agriculture drone page presents the service; request a quote stating areas, forage crops and desired frequency.