NOVELTY - Regulating the fermentation of liquid manure, comprises: (a) initiating the liquid manure within 3 days after the placement of the sewage in an upwardly open fermentation vessel, with an average residence time of 1 hour to 10 days; (b) passing the liquid manure into the stirring device (6), by a suitable paddle or screw as propeller, in a horizontal circular flow motion around a wall located in the center of the container or a separating element; and (c) helical mixing of the liquid manure in the entire cross section of the fermentation vessel.    USE - The method is useful for regulating the fermentation of the liquid manure.    ADVANTAGE - The method reduces the loss of nutrients of the liquid manure by avoiding the emission of ammonia, reduces the viscosity of the liquid manure and the method provides the degradation of the bile-substances which leads to the reduction of the odor emissions. The method makes use of the already existing micro-organisms in the liquid manure and thus avoids the addition of the microorganism strains or the enzymes and thus the method is cost-effective.    DETAILED DESCRIPTION - Regulating the fermentation of liquid manure, in which the viscosity and odor emissions can be prevented under nitrogen losses, comprises: (a) initiating the liquid manure within 3 days after the placement of the sewage in an upwardly open fermentation vessel between manure duct and manure storage for regulated fermentation, with an average residence time of 1 hour to 10 days; (b) passing the liquid manure into the stirring device, by a suitable paddle or screw as propeller, in a horizontal circular flow motion around a wall located in the center of the container or a separating element; and (c) helical mixing of the liquid manure in the entire cross section of the fermentation vessel on at least one side of the centrally mounted wall or of the separation element and on at least a place, caused by the stirring device with a rotation frequency of 20-200 revolutions per minute and with a maximum tip speed of the stirring element of 300 meter/minute and a maximum flow rate of the liquid manure of 20 meter/minute. The fermentation vessel is designed with at least one measuring device for the pH-value and a dispenser for acids or acidic liquids, with which a pre-programmed pH value, preferably pH 6.5 with a deviation of maximum 0.2 units can be kept constant. An INDEPENDENT CLAIM is also included for a device for regulated fermentation of the liquid manure, comprising an upwardly open fermentation vessel, an inlet for the sewage, an overflow mechanism for the treated liquid manure, a stirring device, which is situated within a flow pipe (5), an actuator (2) with a cardan shaft for the stirring device, a central wall, to which the liquid manure is moved by the stirring device under helical mixing, an acid storage tank (1) and a dosing valve (3) for the acid and a measuring system, a conductivity probe, where the dosing valve is controlled with respect to the measurement values of the measuring devices.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of a fermentation vessel.    Acid tank (1)    Actuator (2)    Dosing valve (3)    Flow pipe (5)    Stirring device (6)