NOVELTY - Use of base-modified biomass as bedding for animals in a barn, is claimed. The base-modified biomass is obtained by (i) providing a quantity of stalks originated from at least one plant species, (ii) cutting the stalks to obtain an amount of reduced-length stalks, (iii) optionally grinding the reduced-length stalks to obtain stalk flour, (iv) pressing reduced-length stalks or stalk flour to obtain an amount of compressed biomass, (v) cooling the compressed biomass to obtain an amount of compressed biomass pellets, and (vi) rolling the biomass pellets to obtain base-modified biomass.    USE - The base-modified biomass is useful as bedding for animals in a barn, and in raw material for producing methane (all claimed).    ADVANTAGE - The base-modified biomass increases methane yield for biogas fermentation in 45 days, preferably 10 or 5 days (claimed), is safe, and can be produced without dust formation in simple, environmentally friendly and cost-efficient manner.    DETAILED DESCRIPTION - Use of base-modified biomass as bedding for animals in a barn, is claimed. The base-modified biomass is obtained by (i) providing a quantity of stalks originated from at least one plant species, (ii) cutting the stalks to obtain an amount of reduced-length stalks, (iii) optionally grinding the reduced-length stalks to obtain stalk flour, (iv) pressing reduced-length stalks or stalk flour to obtain an amount of compressed biomass, (v) cooling the compressed biomass to obtain an amount of compressed biomass pellets, and (vi) rolling the biomass pellets to obtain base-modified biomass. The biomass is base treated during the steps (i)-(vi). INDEPENDENT CLAIMS are also included for:    (1) a raw material as feed in a biogas reactor to produce methane, comprising the above base-modified biomass and manure of at least one animal;    (2) use of raw material for producing methane; and    (3) producing methane, comprising providing the base-modified biomass, using the base-modified biomass as bedding for animals in the barn, mixing and absorbing the base-modified biomass with manure of the animals in the barn to obtain raw material, feeding the biogas reactor with the raw material, converting the raw material to methane and optionally other products using microorganisms in the biogas reactor, and collecting the methane.