An agroenergetic assessment of technological cultivation methods for perennial herbaceous legumes that ensure stable phytomass yields under the conditions of the Central Fore-Caucasus was carried out. The research objects were regionally adapted varieties of blue-hybrid alfalfa, red clover and Hungarian sainfoin cultivated in the North Caucasus region, as well as environmental factors limiting the process of symbiotic atmospheric nitrogen fixation. The results of the energy assessment carried out showed that the energy input was identical for all the crops studied and differed by 2.65-2.67 GJ/ha in terms of the cost of the second cut for the blue-hybrid alfalfa and red clover crops. When growing blue-hybrid alfalfa, an energy yield from 32.37 GJ/ha was achieved in the control variant to 38.08 GJ/ha in the variant with the most active symbiotic nitrogen fixation. The energy costs for hay and protein had the opposite pattern and decreased to 5.55 GJ/t hay and 32.27 MJ/kg protein. The cultivation of red clover gave an energy yield of 21.73...26.88 GJ/ha, with the amount of energy increasing with the improvement of plant nutrition. When all the factors investigated were optimized, 23.7 % more energy was obtained compared to the control. In the Hungarian sainfoin crop, the patterns were similar between the variants, but they had the worst energy indices among the crops studied. Thus, only 19.04...22.62 GJ/ha of energy were obtained at harvest, the cost price of hay in the best variant was 8.03 GJ/t, protein – 52.8 MJ/kg, making the fodder obtained the most expensive of the experiment.
Abasov et al. (2025) studied this question.