Novel Willow Header Adapted to a Pull-Type Forage Harvester:Development and Field Experiments

Abstract

Abstract. Short-rotation woody crops (SRWC) were initially developed for large-scale biomass production. Today, several machinery manufacturers offer large woody crop headers adapted to self-propelled forage harvesters (SPFH) with reported wet matter (WM) capacities of 40 to 120 t WM/h, depending on engine power (from 300 to over 600 kW). Over the last 20 years, SRWC have often been developed on small plantations, 1 to 5 ha, because of market uncertainty for biomass value and small-scale opportunities such as phytoremediation, riparian buffers, wastewater treatment, and modest use of cultivated biomass for heating energy in rural areas. Few machines are available to harvest SRWC efficiently, in the form of wood chips, over small areas. This article presents the development and evaluation of a novel “willow” header adapted to a commercial medium-size pull-type forage harvester (PTFH, Dion model F41, Boisbriand, QC, Canada). The prototype header includes two 0.6 m diameter saws, two vertical paddle axes, and a central pallet conveyor to rotate and push cut stems to the forage harvester feed rolls. In field trials, the prototype processed SRWC at an average rate of 30 t WM/h (continuously, excluding time loss) when operated with a 224 kW tractor, in high yielding willow (17 to 42 t DM/ha), including more than 80,000 stems/ha and average diameters from 17 to 30 mm at the point of cut (10 cm above the ground or D10). The prototype also successfully harvested larger diameter poplar (D10 averaged 53 mm; maximum of 97 mm) at a slower rate (average of 15 t WM/h), possibly also because of a low yield (6,800 stems/ha, 8 t DM/ha). When using a smaller tractor (118 kW), power was a limiting factor and average harvest rate was lower (11 t WM/h). Components and assembly costs for the header represented about $30,000 (excluding spare and oversized parts); retail cost of a future commercial header could range between $60,000 and $80,000, in addition to the PTFH (about $35,000) and tractor. The availability of such a header could stimulate the development of SRWC and biomass production on numerous fields currently abandoned or of limited value to agricultural production.