Water requirements of crops

WR = CU + Application loss + Water needed for special operations

Water requirement of any crop is fulfilled through precipitation oreffective rainfall (ER), soil profile

contribution including that from shallow water table (S).

WR = IR + ER + S

Factors influencing water requirements

Water requirement of any crop depends on the following four factor which are:

1. Crop factor: such as variety, growth stage, duration, plant population and growing season.
2. Soil factor: such as texture, structure, depth and topography.
3. Climatic factors: such as temperature, relative humidity, wind velocity
4. Crop management practices: such as tillage, fertilizer application, weeding etc.

Water use efficiency (WUE)

Water use efficiency is defined as the yield of marketable crop produced per unit of water used in evapotranspiration.

WUE = Y/ ET

Where WUE is water use efficiency (kg/ha mm); Y the marketable yield (kg/ha) and ET is evapotranspiration (mm).