Up to now the environmental performance of agricultural machines has been described taking only net fuel consumption and linking average emission factors. In reality however fuel consumption and resulting emissions depend on both the type of work, i.e. the work load of the motor, and the nominal power of the machine. Our new method accounts for these factors in a differentiated way and examples discussed show its superiority. This allows fuel and emission balances of agricultural processes starting with individual agricultural steps over alternative machine use up to wholesome balances of crop cultivation or the total machine use of working units. Thus the precision and validity of results from LCAs and comparable balancing instruments is improved considerably.