Water Requirements for the Onion as Influenced by Soil Moisture Content and Soil Moisture Tension

Abstract

An experiment was conducted to determine the most optimum moisture content to be depleted and the corresponding soil moisture tension to be maintained for scheduling irrigation for onion (Grane). Three levels were maintained by controlling application of water by sprinkler systems. Evaluation of crop factor K was also tried. Values obtained show changes in yield and transpiration for different levels of moisture depletion and stress.
Moisture depletion between 40 and 50 % of available moisture-corresponding to a soil moisture tension of 230 to 250 millibars was suggested to be maintained for relative maximum yield per unit of water used. A plant factor K equals 0.65 is suggested to be used for the months of April and May. More work is advised where the Penman equation is to be used to evaluate evaporation. Moisture levels to be maintained under different rates of fertilizers application are pertinent before a final conclusion could be precisely followed.