Energy indices in irrigated wheat production under conservation and conventional tillage and planting methods

Conservation tillage system was recommended for soil erosion control in North America for the first time 60 years ago (Wang et al., 2006). Using this tillage system including minimum and zero tillage has been rapidly developed in recent years. Thearea covered by zero tillage in 2006 was 95 million ha all over the world (Dumanski et al., 2006). In addition to saving soil and water resources, conservation tillage system reduces energy consumption and improves energy indices by combining different tillage and planting operations. Results of research conducted in Fars province shows that conservation tillage saves fuel consumption for 77% compared to the conventional system (Afzalinia et al., 2009). Conservation tillage also reduces energy consumption from 23.6 to 42.8% in comparison to the conventional tillage (Rusu, 2005). Since energy indices would be affected by reduced input energies in conservation tillage, this research was conducted to evaluate the effect of different tillage and planting methods on energy inputs and energy indices in irrigated wheat production in Eghlid region.
This research was performed to evaluate and compare the energy indices in irrigated wheat production under different tillage and planting methods. The study was conducted in the form of a randomized complete block experimental design with five treatments and three replications in Eghlid region. The treatments were included, conventional tillage and seed broadcasting (A), conventional tillage and planting with Machine Barzegar grain drill (B), reduced tillage and seeding with Roto-seeder (C), direct seeding with Jairan Sanaat grain drill (D), and direct seeding with Sfoggia direct drill (E). Experimental plots with 10 by 50 m dimensions were used in this study. Loss crop residues were taken out of the experimental plots and standing crop residues were retained in the plots. In the conventional tillage method, primary tillage was performed using a moldboard plow and secondary tillage operation was done using a disk harrow and land leveler. Seed bed was prepared in the reduced tillage method using a tine and disc cultivator which was able to complete the primary and secondary tillage operations simultaneously. Wheat seed was directly planted using direct planter without any seed bed preparation in the zero tillage method. Surface irrigation method was used to irrigate the plots and 11970 m3/ha water was consumed in each treatment. Input energies including direct energy (diesel and electricity) and indirect energy (water, labor, seed, fertilizer, chemicals, and machinery) were measured and calculated. Output energies (energy of grain and straw) were measured in each treatment and the share of each input energy, energy ratio, net energy gain, and energy productivity were determined and compared. Collected data were analyzed using SAS software and Duncan’s multiple range tests was used to compare the treatments means.
Results showed that tillage and planting methods had a significant effect on fuel and machinery energies; while, the total input energy, crop grain yield, and crop biologic yield were not affected by the tillage and planting methods (Table 4). Fertilizers and chemicals had the highest contribution in input energy of all treatments. Results also indicated that reduced tillage and seeding with Roto-seeder had the highest energy ratio (1.46) and the lowest energy ratio (1.40) was related to the conventional tillage methods (Fig.1). The highest net energy gain (47653 MJ) was obtained from the reduced tillage and seeding with Roto-seeder; while, the lowest amount of net energy gain (41388 MJ) was related to the conventional tillage and planting with Machine Barzegar grain drill (Fig.3). Results also showed that the reduced tillage and seeding with Roto-seeder had the highest energy productivity (0.115 kg MJ-1) and the conventional tillage treatments had the lowest energy productivity of 0.110 kg MJ-1 (Fig.4).
Results of this study showed that conservation tillage treatments (minimum and zero tillage) reduced total energy consumption (input energy) by decreasing fuel consumption and mechanical energy (energy of machinery) compared to the conventional tillage. Therefore, conservation tillage treatments had the higher energy ratio, net energy gain, and energy productivity compared to the conventional treatments. For this reason, conventional tillage and planting methods could be replaced with conservation tillage systems in Eghlid region. Meanwhile, in order to obtain more accurate results in energy indices comparison, differences in water consumption in various tillage and planting methods should be also considered.