A method for controlling operation of an agricultural machine, comprising - providing a portable device, the portable device comprising an input device, a processing unit, a storage unit, an output device, and a transceiver device configured for wireless data transmission, - receiving a voice control command over a microphone device of the input device of the portable device, - determining command text data from the voice control command by processing the voice control command by a speech recognition application running on the processing unit of the portable device, - outputting the command text data over a display of the output device of the portable device, - outputting a request for a user input over the output device of the portable device, - in response to the outputting of the command text data and the request for the user input, receiving a user confirmation input confirming that the command text data were correctly determined from the voice control command, - providing machine control signals assigned to a machine control function in a control device of an agricultural machine located remotely from the portable device, the control device of the agricultural machine comprising a processing unit and a transceiver device configured for wireless data transmission, wherein, prior to providing the machine control signals, it is determined whether the user confirmation input was received, and wherein the providing of the machine control signals comprises - determining control function data indicating the machine control function from the command text data, and - processing the control function data for generating the machine control signals, and - controlling the operation of the agricultural machine according to the machine control signals. - providing a portable device, the portable device comprising an input device, a processing unit, a storage unit, an output device, and a transceiver device configured for wireless data transmission, - receiving a voice control command over a microphone device of the input device of the portable device, - determining command text data from the voice control command by processing the voice control command by a speech recognition application running on the processing unit of the portable device, - outputting the command text data over a display of the output device of the portable device, - outputting a request for a user input over the output device of the portable device, - in response to the outputting of the command text data and the request for the user input, receiving a user confirmation input confirming that the command text data were correctly determined from the voice control command, - providing machine control signals assigned to a machine control function in a control device of an agricultural machine located remotely from the portable device, the control device of the agricultural machine comprising a processing unit and a transceiver device configured for wireless data transmission, wherein, prior to providing the machine control signals, it is determined whether the user confirmation input was received, and wherein the providing of the machine control signals comprises - determining control function data indicating the machine control function from the command text data, and - processing the control function data for generating the machine control signals, and - determining control function data indicating the machine control function from the command text data, and - processing the control function data for generating the machine control signals, and - controlling the operation of the agricultural machine according to the machine control signals.