Grain yield and energy efficiency of a barley dry land farming system as affected by supplemental irrigation at flowering stage

Energy efficiency is an important index for evaluating the sustainability of cropping systems. Therefore, the effect of supplemental irrigation on grain yield and energy efficiency of barley was evaluated under dry land farming system. The experiment had two treatments (with and without supplemental irrigation at flowering stage) and seven replications. Grain yield was evaluated by measuring grain yield, spike per unit area, grain per spike, 1000-grain weight, biological yield and harvest index. Energy efficiency of the system was evaluated by calculating input energy and output energy of the system used for measuring energy ratio and net output energy indices. Results indicated that supplemental irrigation at flowering stage, increased barley grain yield from 1523.56 to 2259.29 kg.ha-1 affected by grain number per spike, since 1000-grain weight and spike per unit area were not significantly affected by supplemental irrigation. Total energy input of barley dry land farming was 29812 MJ.ha-1. Supplemental irrigation was resulted in 683 MJ.ha-1 energy addition to cropping system. However, because of 48 percent increasing in grain yield resulted in 10819 MJ.ha-1 energy output of the system, which increased energy ratio and net output energy to 45 percent and 10133 MJ.ha-1, respectively. Therefore, a supplemental irrigation at flowering stage, addition to increasing of grain yield, can improve energy efficiency of barley dry land farming system.