LCA evaluation of walnut production in different irrigation methods: A Case Study of Shahrekord and Saman Counties

Today, the increase in food demand has led to an increase in energy use, which has some environmental consequences such as air pollution and global warming. Irrigation is one of the energy-intensive operations in agriculture, which consumes great part of energy inputs and has harmful environmental effects. Applications of modern methods of irrigation in agriculture can be considered from different aspects. So, the aim of this study was to evaluate the energy and environmental indicators of walnut orchards under surface and pressured irrigation methods. The required data, including information about inputs and energy consumed in walnut orchards, were collected using questionnaires and face-to-face interviews in Shahr-e Kord and Saman region of Chaharmahal and Bakhtiari province. The collected data belonged to the production period of 2021–2022. The averages of total energy consumed for walnuts production in pressured and surface irrigation systems were 29573.53 and 25058.46 MJ ha−1, respectively. This shows that despite less water consumption in the pressured irrigation system, the total energy input in this irrigation system is more than the surface irrigation system. No significant difference was observed regarding the performance of walnut in the two mentioned irrigation systems. The inputs energy consumption in the walnut production with the pressurized irrigation system were highest for plastic and farmyard manure (about 32% and 15%, respectively); while in surface irrigation system, the share of nitrogen fertilizer and farmyard manure were highest (about 30% and 25%, respectively). Energy ratio of walnut production in surface irrigation systems was computed as 3.58, while the corresponding value in pressured system was 2.77. In other words, surface irrigation had better conditions in terms of energy indicators. The LCA results of walnut production showed that in the two irrigation systems, the greatest effects in human health and the ecosystems are from on-farm emissions. In general, the investigation of the environmental indicators of walnut production in the two irrigation systems showed that the use of the pressured irrigation system reduces the environmental damage.