Irrigation Requirements and Trends of Citrus Orchards in the City of Ramsar

Irrigation of citrus, as one of the major fruit crops in Mozandaran province is of particular importance during spring and summer, because of reduced precipitation and crop sensitivity to water stress. This study was performed to manage irrigation of citrus orchards in Ramsar city. In this study the soil water balance equation was used in the Excel environment to calculate time and number of irrigations needed for a citrus orchard over a 30-year period, using data from meteorological stations in Ramsar city. The results showed that in April, 100% of irrigation water requirement is met by precipitation. During May and September, 63% of the 30 years did not require Irrigation. For June, July and August, respectively, in 67%, 73% and 73% of the years irrigation was needed, which it was shown that the probability for irrigation during June, July and August were respectively higher for the final 10-days, middle 10-days and initial 10-days of these months. The calculated irrigation water per irrigation was 84 mm. According to results, July and August are the hottest months in the city of Ramsar. The Man-Kendall test results showed that during the past 30 years the number of irrigations for spring and summer increased due to rising temperatures and evapotranspiration and reduced rainfall, but it was not statistically significant. However, significant increase in temperature and evapotranspiration was observed during autumn.