SOIL MOISTURE DEPLETION, EVAPOTRANSPIRATION AND CROP COEFFICIENTS FOR OLIVE TREES CV. KALAMON, FOR DIFFERENT LEVELS OF SOIL WATER POTENTIAL AND METHODS OF IRRIGATION.
Soil moisture reserve depletion in the non wetted areas of the irrigated treatments, was greater than that of the wetted ones of the same treatments, but about the same to that of the non irrigated treatment. Soil moisture reserve depletion in the non wetted areas of the irrigated and non irrigated treatments occurred mainly (60–70%) during May-June. Soil moisture was reached wilting percentage during September in the non wetted areas of the irrigated treatments and during August in the areas of the non irrigated ones. Total soil moisture reserve depletion was generally greater in the deeper soil layers of the wetted areas and in the upper soil layers of the non wetted areas. Amount of irrigation water used was higher at -0.02 MPa than at -1.5 MPa but it was not notably different between drip and basin methods within the same soil water potential level.
Evapotranspiration of irrigated trees during May-September period was met mainly from irrigation water (80–90%), less from the natural reserves of the soil moisture (10–15%) and even more less from the rainfall of the respective period (2.5–5%). Crop coefficient, as an evapotranpiration to class 'A' pan evaporation ratio, increased from 0.4 to 0.6 for the -0.02 MPa, was constant at about 0.3 for the -1.5 MPa and reduced from 0.2 to 0.05 for e non irrigated treatment. Crop coefficient was not notably different between drip and basin methods within the same soil water potential level.