The field is a grid of soil cells, each with its own moisture level that dries out through evapotranspiration and occasionally gets topped up by rain. A monitoring drone sweeps the field in a boustrophedon (row-by-row) scan path, the way a real IoT sensor pipeline or multispectral drone pass reports readings one strip at a time. Only cells the drone has already passed over this sweep are "known" — irrigation can only act on a reading the sensor grid actually produced.
moisture -= evapRate·dt (drying)
if VRI: irrigate cell only if moisture < threshold
if Uniform: irrigate every cell, regardless of reading
health → target(moisture) where target peaks at the optimal band
efficiency = Δhealth / waterUsed
- Dry threshold — the moisture reading below which variable-rate irrigation (VRI) decides a cell needs water; uniform mode ignores this and waters everything.
- Drone scan speed — how fast the sensor sweep covers the field; a slower sweep delays VRI's response to a cell that just dried out.
- Irrigation rate — how much moisture each watering pass adds; higher rates fix deficits faster but push water use up for both strategies.
- Precision vs Uniform — VRI applies water only where the sensor grid reports a deficit, holding crop health with a fraction of the water that blanket irrigation spends watering cells that were already fine.
Real-world relevance: this sense → decide → apply loop — soil-moisture sensors or drone multispectral scans feeding a variable-rate controller — is the core mechanism precision agriculture uses to cut water and fertilizer use while holding or improving yield compared with uniform field-wide application.