Skip to main content

Crop water requirement and its factors

Short answer

Crop water requirement is the total water needed for full crop growth, including evapotranspiration and application losses. Factors are climate (temperature, humiditty, wind, sunshine), crop type and duration, soil texture, water table depth, effective rainfall, irrigation method and efficiency, tillage and mulching, salinity, and season.

What do you mean by crop water requirement? Explain the factors affecting the crop water requirement.

Crop water requirement (CWR) is the total quantity of water, regardless of its source, needed by a crop to grow to maturity. It includes consumptive use (evapotranspiration) plus losses during application (percolation, seepage, runoff) and special needs (puddling, leaching):

CWR=ETc+losses+special needsCWR = ET_c + \text{losses} + \text{special needs}

and the irrigation requirement is CWR−Pe−CWR - P_e - soil moisture used.

Factors affecting CWR

  1. Climate: higher temperature, more sunshine hours, stronger wind and lower humidity all increase evapotranspiration.
  2. Crop: type, variety, leaf area, root depth and growth stage; rice and sugarcane have a high CWR.
  3. Crop period: longer periods need more water.
  4. Soil: texture, structure and infiltration; sandy soil has more deep percolation.
  5. Water table: a shallow water table contributes capillary water.
  6. Rainfall: its distribution and the effective rainfall.
  7. Method and efficiency of irrigation: surface methods lose more water than drip or sprinkler.
  8. Agronomic practices: tillage, mulching, planting date, spacing and weed control.
  9. Salinity of soil and water: extra water is needed for leaching.
  10. Season and altitude of the area.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Irrigation and Drainage Engineering chapter 2 questions →