Analysis of the Physical Efficiency Indices of Water and Energy in Alfalfa and Barley Crops in Two Different Climates

IntroductionIn today's world, challenges related to agriculture, food security, water and energy resources, productivity, and greenhouse gas emissions have emerged as significant issues for global societies. Through their international impacts, these challenges have led to economic, social, and environmental changes on a global scale. One of the most crucial issues that should be highlighted is the shortage of water resources. Water, as a vital factor in agriculture and food production, holds special importance. Therefore, in order to achieve sustainable agriculture, it is necessary to pay attention to the energy indicators, the efficiency of water consumption in the production of agricultural products and the amount of greenhouse gas emissions. In general, a combination of energy indicators, water efficiency and reduction of greenhouse gas emissions in agriculture can help to develop sustainable agriculture and preserve the environment and help to provide safe and accessible food for the society. The aim of the present study was to investigate the indicators of physical water, energy efficiency, and greenhouse gas emissions on alfalfa and barley crops in two different climates: a warm and arid climate (Shahr-e-Qom Plain, Qom) and a temperate and humid climate (Sari Plain, Mazandaran). This was done to assess the impact of climate on the outcomes of these indicators. Materials and MethodsTo investigate the physical water efficiency and evaluate energy indicators in this study, major agricultural products in Sari and Sharifabad Plains, including barley and alfalfa, were analyzed using cross-sectional data from the agricultural year 2021-2022. Initially, the sample size was determined based on the Cochran formula and the Bartlett method (2001). Subsequently, sampling was carried out using a questionnaire designed by the researchers themselves. The questionnaires totaled 250 (Sari Plain: 150, Sharifabad Plain: 100), and the collected information included the amount of input consumption and production quantity. The questionnaire, designed by the researcher, was validated for validity and reliability by experts and specialists. The inputs used in the study of water efficiency and energy indicators for the mentioned products in Sari and Sharifabad Plains included person-days of human labor, machine working hours, fuel consumption of machines, the quantity of nitrogen, phosphorus, potassium fertilizers per hectare, the quantity of various chemical pesticides (herbicides, fungicides, and insecticides) per liter per hectare, the amount of water consumption in cubic meters per hectare, and the amount of seed consumption in kilograms per hectare.Results and DiscussionThe results of the descriptive statistics of input consumption in Sari and Sharifabad Plains in barley and alfalfa crops showed that the highest input consumption of manpower in the cultivation of alfalfa crops in Sharifabad Plains with an average of 225 hours per hectare, the highest amount of fertilizer consumption related to the alfalfa crop in Sharifabad Plain is related to nitrogen fertilizer with an average of 130 kg per hectare, the highest amount of fuel consumption of machinery related to alfalfa crop in Sari Plain with an average of 405 liters per hectare, the highest amount of water consumption related to alfalfa crop in Sharifabad Plains with an average of 17500 cubic meters per hectare and the highest yield of alfalfa was obtained in Sharifabad Plains with an average of 11550 kg per hectare. The obtained results indicated that the highest input energy level in Sharifabad Plain for alfalfa was 5,674.50 MJ per hectare. The results of energy efficiency indicated that alfalfa production in Shahrifabad Plain had the highest value with 0.19 kilograms per MJ, while this index for alfalfa in Sari Plain was 0.13 kilograms per MJ. Additionally, the energy efficiency for barley in Shahrifabad Plain was 0.13 kilograms per MJ, and for Sari Plain, it was 0.12 kilograms per MJ, showing a somewhat similar level. The physical water use efficiency results revealed that the highest and lowest efficiency levels were observed for barley in Sari Plain, amounting to 0.96 kilograms per cubic meter, and for alfalfa in Shahrifabad Plain, amounting to 0.57 kilograms per cubic meter, respectively. Furthermore, this index for alfalfa in Sari Plain was 0.67 kilograms per cubic meter, and for barley in Shahrifabad Plain, was 0.8 kilograms per cubic meter. The results for greenhouse gas emissions demonstrated that the level of emissions in Sari Plain was higher than Sharifabad Plain, attributed to excessive fertilizer and pesticide use in Sari Plain. The highest greenhouse gas emissions in Sari Plain for alfalfa were 2681.65 kilograms of CO2 per hectare, while in Sharifabad Plain, was 2351.85 kilograms of CO2 per hectare. ConclusionThe overall results indicated that crop performance in humid regions was not higher than in dry and semi-arid regions, and this index depends on various parameters, including water consumption and managerial considerations. However, water consumption in temperate and humid regions is significantly lower than in dry and semi-arid areas due to higher precipitation. This result is increased efficiency in temperate and humid regions.