🌾 Farm Water Balance & Carbon Lab

About this simulation

Agronomists plan irrigation by comparing crop water demand (evapotranspiration, or ET) against the water actually supplied by rain and irrigation. A shortfall — the irrigation deficit — dries the root zone and caps yield. At the same time, every input has a carbon cost: nitrogen fertilizer drives soil microbes to release nitrous oxide, pumping irrigation water burns energy, and disturbing the soil through tillage oxidizes stored soil carbon back into CO₂.

How it works

• Water deficit = evapotranspiration demand − irrigation applied. A positive deficit drains the soil-moisture cutaway and stresses the crop.
• Yield index combines a water-stress penalty with a diminishing-returns nitrogen response curve — too little nitrogen limits growth, too much wastes it and risks lodging.
• Net GHG footprint sums nitrous-oxide emissions from fertilizer, pumping energy from irrigation, and the soil-carbon effect of tillage (no-till sequesters carbon; conventional tillage releases it).
• Rising red motes over the field mark net carbon emission; sinking green motes mark net carbon drawn back into the soil.

Controls

• Irrigation applied — millimetres of water delivered per day.
• Evapotranspiration demand — how thirsty the climate is that day (heat, wind, sunlight).
• Nitrogen fertilizer — kilograms of nitrogen applied per hectare.
• Tillage practice — no-till leaves soil carbon undisturbed; conventional tillage turns the soil and releases it.

Did you know?

Precision-agriculture soil moisture probes let real farms irrigate to within a few millimetres of actual crop demand, cutting water use by 20–30% versus fixed calendar-based schedules while holding yield steady.