It mainly depends on the effective root zone depth of the crops. Only upper 50% roots can suck and supply water to plants and any water going beyond this depth is not available to plants. Again the balance of Air and water in the soil is healthier for the plant . Thus on an average a Rain Gun model V-Skipper or Hidra can irrigate nearly 1/2 acre per position in about 1.5 to 2.5 pumping hours depending on the soil type, season and crop being irrigated. Using Flood irrigation, farmers nearly take much more time and water to irrigate as no control can be exercised.
