Assessment of Agricultural Water Productivity for Tea Production in Tea Fields of Guilan Province

Water productivity index is one of the main factors in efficient use of water for agricultural products. In this study، the rate of water productivity (WP) in six irrigated tea fields and three rainfed (no irrigation) were assessed by farmer’s management for two years (2009-2010). Yield of each tea field in successive harvests، soil moisture monitoring by gravimetric soil and use of water balance equation was conducted during the growing seasons. Volume of water entered to irrigation system and amount of water reached to surface level were also measured. Tea mean yield in irrigated and rainfed field were 2843 and 1095 Kg. ha-1، respectively. Average of gross irrigation and effective rainfall (WP) and irrigation water productivity (IWP) in the irrigated fields were 4. 39 and 4. 55 kg (made tea) ha-1 mm-1 and average of net WP (actual evaportanspiration) and net IWP was 5. 18 and 6. 61 kg ha-1 mm-1، respectively. Average WP in rainfed tea fields was 3. 4 kg ha-1 for each mm of effective rainfall. The most effective factors on WP reduction in tea fields were improper harvesting operations (un standard plucking) and economic problems. Moreover، improper operation and maintenance and old irrigation systems and unprincipled irrigation scheduling in irrigated tea fields were also effective on WP reduction. Comparing the results of this study with other studies in past، showed that by implementing the proper methods in irrigation management and appropriate agricultural practices can improve water productivity in tea fields.