آبیاری بارانی

Energy flow is one of the most important issues in agroecology. The amount of energy that is consumed in different agroecosystems not only depends on the type of crop but also on the material and methods that is used in its production. Potato plants are one of the most important crops that is produced in Torbat Heidarieh region, Khorasan Razavi Province of Iran. Different irrigation methods influence the energy consumption and production. Thus, the aim of this study is to compare energy efficiency of potato with different irrigation methods.

In order to evaluate and compare the efficiency of energy consumption in potato production based furrow,  sprinkle and drip irrigation methods, a study was carried out at 11 fields in the Jolgeh Rokh Torbat Heidarieh region in 2013- 2014 . The comparison was performed using a completel randomized, unbalanced design. In which the type of irrigation system was considered as the treatment and fields that were matched to each irrigation system as a replication. The studied traits included the amount of input and output energy, the equivalent energy of all inputs, and energy use efficiency, net energy, energy production and specific energy.                                                                                                                                         

The largest amount of energy consumed by the human labor was due to furrow irrigation. The highest average of fossil fuel consumption was due to furrow irrigation method followed by sprinkle and drip irrigation. The amount of electricity consumed in the drip irrigation method had the highest amount compared to the other two methods. The most energy consumed by nitrogen fertilizers was related to furrow irrigation method, and the methods of irrigation of droplets and sprinklers in this regard were ranked in the following order, respectively. The amount of energy consumed by phosphorus fertilizers in irrigation was the least amount of droplets. This amount was in sprinkler irrigation and furrow irrigation respectively, although there was no significant difference between the two methods. The energy of using potassium fertilizers in the highest irrigation system was similar to the other irrigation systems. The energy consumption of herbicides was highest in drip methods and furrow irrigation was in the next category. Energy consumption of machinery was highest in sprinkler irrigation method. In the recent method, energy consumption of machinery was about half of the energy consumption of the total inputs. Indirect energy consumption for drip irrigation system was 6868 MJ.ha-1 and in sprinkle irrigation 2756 MJ.ha-1. Energy produced by seed was highest in drip irrigation method and the lowest in sprinkle irrigation. The total amount of input and output energy in sprinkler irrigation method was the highest (106674.24 and 162000 MJ.ha-1), followed by drip irrigation (97807.82 and 151000 MJ.ha-1) and furrow irrigation (92539.61 and 139000 MJ.ha-1) were placed in the following categories. The energy use efficiency of the drip irrigation method 1.6 was more than other irrigation methods. Production energy in terms of amount of drip and furrow irrigation was the highest 0.44 and in sprinkle irrigation 0.41. Net energy was the highest in sprinkler irrigation (53392.18 MJ.ha-1) and the lowest in furrow irrigation (46660.38 MJ.ha-1). Production energy was highest in drip and furrow irrigation (0.44 and 0.43) and lowest in sprinkle irrigation (0.41). The specific energy in furrow irrigation (2.36) was higher than the other methods and in the drip irrigation with the lowest (2.32).                                                                               

According to the results of the present research, in spite of higher yield of potatoes under sprinkle and drip irrigation systems, there were not significant differences among the energy indices; energy efficiency, energy productivity, and special energy; of three systems. This was due to more total input energy in the sprinkle and drip systems. Because the machinery and installations energy input in furrow irrigation system were lower than two other systems.

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.