The research defined energy inputs involved in organic (farmyard manure, total plant biomass and post-harvest residue of undersown catch crop) and mineral fertilisers (400, 600 kg NPK·ha^-1). There were estimated energy value of feed undersown-catch-crop yield, of sugar beet root and leaf yield and energy effectiveness index. The highest energy inputs were observed in the combination fertilised with post-harvest residues of Italian ryegrass. The application of the total hop medick biomass and its post-harvest residue under sugar beet, as compared with the farmyard manure, decreased the energy inputs per 1ha, respectively, by 59.99 and 41.67%. An increase in the level of mineral fertilisation with NPK increased energy inputs and energy value of sugar beet yield, yet decreased the value of energy effectiveness index. The sugar beet yield energy value was highest in the object fertilised with the total plant biomass of the hop medick and Italian ryegrass as well as with the total plant biomass of hop medick and with 600kg of NPK·ha^-1. The highest energy effectiveness index was obtained for the combination fertilised with the total plant biomass of hop medick.

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