💧 Irrigation & Soil Water Balance

Root-zone water column (PWP ↔ FC) with MAD trigger

Soil moisture over the season — irrigation events & stress periods

Season results

Current soil moisture—

Root-zone depletion D_r—

Days to next irrigation—

Total irrigation applied—

Crop water use (ET)—

Water-use efficiency (ET/(I+P))—

Stress days—

Soil water balance. Each day ΔS = P + I − ET − D − R: precipitation P and irrigation I add water; evapotranspiration ET = ET₀·Kc removes it; excess above field capacity is lost to deep drainage D, and intense rain to runoff R. Plant-available water (TAW) lies between field capacity (FC) and the permanent wilting point (PWP). Irrigation refills the root-zone depletion D_r. Readily available water RAW = MAD·TAW sets the refill trigger; once D_r exceeds RAW the crop is stressed (green → wilting yellow). Sandy soils hold little water and need frequent small irrigations; clay holds more but drains slowly.