Technical Abstract: Utilization of alfalfa could be greatly improved if protein-rich leaves were efficiently separated and preserved from fibrous stems. This work envisions a new harvest scheme combining three processes: mechanical leaf separation, dewatering, and fermentation. Gross plant fractionation is accomplished by in-field mechanical separation of leaves from stems. This operation foregoes field wilting of the leaf fraction, thereby minimizing losses associated with plant and microbial respiration and weather. However, leaves are moist and not biologically stable, even when ensiled conventionally. To overcome this limitation, the next step in the proposed system is to dewater the leaves. To quantify the effectiveness of leaf dewatering, experiments were conducted in which leaves were dewatered in a replicated factorial experiment including maceration and four levels of backpressures in a single-screw press. The amount of juice extracted varied proportionally with press backpressure from 38 to 121 L per Mg of fresh leaves and was composed of about 90% water. The resulting dewatered leaf press-cakes were successfully ensiled and were found to be compositionally similar to high-quality, whole-plant alfalfa silages. Additionally, we demonstrated that the nutritionally valuable components in the juice could be conserved by anaerobic storage, or the press-filtrate could be simply returned to the field with low losses of leaf dry matter and protein of 2.0 and 2.5%, respectively.