عنوان مقاله [English]
Iran has dry climate conditions that its rainfall is lower than one third of rainfall in world. The results of anticipation illustrated that renewable water resource in Iran will be lower than 1500 m3 year-1, which it will cause critical level in water issue. Sugar beet is consumed high water and this issue cause to limitation of cultivated area in regions where water resources is determinate. Therefore, using classical irrigation systems instead of furrow irrigation systems was occurred in last decades. Therefore, evaluation of the water usage efficiency in different irrigation systems under field conditions is necessary. Mirzaei and Ghadami Firozabadi (2007) evaluated the water use efficiency under two different irrigation systems included furrow and classical systems in sugar beet in Ekbatan research site of Hamedan. They reported that the highest water use efficiency in term of physical was related to drop irrigation and the lowest amount was observed in furrow system. The goal of the study was to evaluate water productivity in terms of physical and economical in sugar beet fields in Hamedan province.
Materials and methods
This study was performed by using questionnaire, observation and also interview with farmers in 2017. Studied area was four counties of Hamedan province included Nahavand, Asadabad, Toyserkan and Famenin. Water productivity was calculated by two different methods which were physical and economical. Simple way to calculate the physical water productivity under field conditions is crop per drop (CPD) index. In this method, produced yield was considered per used drop. Higher value of CPD index indicates the correct use of water. The concept of economical water productivity is benefit per drop (BPD). BPD index considered the gross benefit and it is the limit of this index, so another index named NBPD was used. In NBPD index, net benefit was considered.
Results and discussion
Yield of sugar beet was considered based on average yield in each county and the price of sugar beet was determinate based on sugar beet price in 2017 year and it was 2916 Rials kg-1.
The results showed that yield and total income of sugar beet in Hamedan province and its counties under classical irrigation system was higher than furrow one, so that applying classical system caused to increase in gross benefit as 18% compared to Furrow system. As data, sugar beet production cost in furrow approach was 14.96% lower than classical method in total province. Net benefit was gained by subtract of production cost from gross benefit for each county. The study results illustrated that net benefit of sugar beet for farmers who use classical irrigation system was higher than farmers who use furrow way to irrigate their fields. Average of net benefit by sugar beet production in furrow and classical systems was 83381.47 and 110269.53 (1000Rials ha-1), respectively that indicates 32.2% increase in net benefit under classical system in comparison with furrow system. Water consumption in furrow approach was higher than classical one in all studied counties of Hamedan province. Asadabad with water consumption as 13476 m3 ha-1 had the highest and Nahavand with 9461 m3 ha-1 had the lowest water consumption among counties. Physical water productivity (CPD) in furrow and classical systems was gained 4.71 kg m3 and 6.85 kg m3, respectively. Results of the BPD values indicated that classical system had more productivity in comparison with furrow in all counties and total province. NBPD values also showed the same results of BPD, so that the value of NBPD under furrow system was observed 6805 Rials m-3 , but for classical system was obtained 11077 Rials m-3. Therefore, water consumption at a rate of one m3 by classical system causes increase in benefit as 4272 Rials compared to furrow.
In general, it can be concluded that applying classical irrigation systems causes increasing of water productivity as physically and economically compared to furrow system. Asadabad had the lowest water productivity among other counties of Hamedan province. Therefore, it is necessary to extend needed information about increasing of water productivity to farmers of this county by agricultural experts and promoters.