Water Management in Horticultural Crops

Introduction

• The average annual rainfall of the country as presented in the previous lecture is 119.4 cm which when considered over the geographical area of 328 mha, amounts to 391.63 mham.
  
• This may be rounded up to 400 mham including contribution of snowfall, which has not yet been assessed.
• When rain falls, a portion evaporates, another portion infiltrates into the soil and rest runs off over the land surface.
  
• If the shower is very light (less than 2.5mm) it moistens the upper soil and evaporates rapidly.
  
• There are 130 rainy days in a year, on 75 rainy days, after the rains, the ground water is evaporated.
  
• On the remaining 55 days of rainfall, there is similar evaporation at the commencement of rainfall.
  
• Taking all these into consideration, it is estimated that out of the average annual rainfall of 400 mham about 70 mham is lost to atmosphere.
  
• Of the remaining 330 mham about 115 mham flows as surface run off and the rest 215 mham soaks into the ground.