NOVELTY - The method involves comparing measurement of diffused gas i.e. methane, emission (13) with a threshold value, of the emission, stored in a storage unit by assigning a predetermined priority level to the measurement. Positioning of a diffused gas emission measurement point is defined in a space using a logic controller of a controlling unit (20) by applying a predetermined stored adjustment that is suitable at the level of priority of the measurement.    USE - Method for measuring emission of diffused gas e.g. methane, carbon dioxide and nitrous oxide, emanating from a monolayer or multilayer emission site e.g. hydrocarbon polluted site, waste storage site, composting site and site for agronomic evaluation of compost, by monitoring emission of the gas after spreading of compost and mud on an agricultural particle, using an autonomous mobile robot (claimed) in a meteorological field. Can also be used for measuring emission of other gases such as ammonia, hydrogen sulphide, mercaptan, methane, hydrogen, nitrogen oxide, oxygen, hydrogen fluoride, chlorine, hydrogen peroxide, sulphur dioixde and sulphur trioxide.    ADVANTAGE - The method permits to measure the diffused gas emission emanating from an emission site, in real time and in a reliable manner, thus varying number and space between measurement points for efficiently considering spatial and temporal variabilities of the emission of the gas by selectively increasing the emission in a strong emissive field. The method permits to measure concentration of the gas in a pit, in a rapid and easy manner and permits to reduce weight and energy consumption of the robot.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an autonomous mobile robot comprising a controlling unit.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic partial sectional view of an autonomous mobile robot for measuring emission of diffused gas emanating from an emission site.    Emission site (1)    Autonomous mobile robot (2)    Lower layer (10)    Ground (12)    Diffused gas emission (13)    Controlling unit (20)