A method for harvesting crop materials each having a grains carrying stalk, includes erecting the stalk, cutting the stalk of the crop materials with two or more cutting blades or elements into a lower base segment carrying no grain and an upper straw segment that carries grains, discarding the lower base segment which carries no grain, threshing the upper straw segment which carries the grains for separating the grains from the upper straw segment, and collecting the grains. A blowing process is used for blowing the upper straw segment away from the grains before collecting device the grains. A determining process is used for determining a length of the lower base segment to be cut before erecting the stalk.