The simulation of agricultural and forestry processes provides a huge potential in terms of process understanding. At the Institute of Mobile Machines and Commercial Vehicles of Technische Universitaet Braunschweig agricultural materials like grass, straw and wood are simulated by using the Discrete Element Method (DEM). The DEM offers the possibility to define different structural models which consist of discrete elements connected by flexible bonds. By parametrising the flexible bonds of the stalks different physical properties can be considered. In order to model the natural behaviour of stalks the physical properties have to be measured in advance. Therefore different test rigs are used. Additionally at the Institute different cutting, conveying and compacting processes of agricultural machinery are regarded. An overview of the key results, the potential of the DEM and future research activities is given.