In both orchards irrigation resulted in dramatic increases of Rs. Soil respiration rates of the orchard with a grass cover were higher than those of the periodically disked soil and, on an annual basis, we estimated 11.79 and 7.84 t ha-1 of carbon emissions out of the soil in the two orchards, respectively. Carbon emissions due to soil respiration of irrigated trees were 7% higher than those of rain-fed ones.