Hemp Mechanical Harvesting Systems

Hemp mechanical harvesting uses modified flax disc-mowers or purpose-built reciprocating-blade cutters operating at 5–8 km/h, cutting stems at 10–20 cm stubble height and windrowing for field retting. Stems are laid in uniform swaths (1.5–2.5 m width) for 3–6 week dew retting. Baling uses modified large round balers (1.2 m × 1.5 m rolls, density 100–150 kg/m³) after partial field drying to 15–18% moisture for storage stability. Green harvesting of fresh stems (moisture 70–80%) for water retting delivers to processing within 24–48 hours to prevent anaerobic fermentation losses. Combine harvesting for seed-fibre dual-purpose varieties uses modified grain combines with specialised straw choppers at 3–5 km/h — seed yield 800–1,200 kg/ha harvested simultaneously with stem material for decortication. Harvesting losses of 5–15% stem material occur in mechanical systems versus 2–5% in manual harvesting still practised in China and India for premium fibre production.