The impact of disc settings and slash characteristics on the Bracke three-row disc trencher’s performance

Abstract

ABSTRACTWhen reforesting, disc trenching is the most common site preparation method in Canada. The settings on today’s disc trenching units can be modified extensively, but the effect of these modifications on the work quality and machine performance is poorly understood. We studied a three-row Bracke T35.a disc trenching unit that used five different disc settings to prepare three sites with five different slash characteristics in New Brunswick. We measured the travel speed and the resulting microsite quality during 2–4 machine passes on all 25 treatment combinations, plus the fuel consumption using an engine control module during 1–3 machine passes on 15 treatment combinations. The results showed no difference in microsite quality between disc settings, but it was significantly higher with seasoned than fresh slash, parallel-aligned than perpendicular-aligned slash, and softwood than mixedwood slash. Fuel consumption was significantly lower with parallel-aligned slash and softwood slash, but it was also markedly lower with the least aggressive disc settings. Our results suggest that increased disc down pressure increases fuel consumption but does not increase microsite quality among slash, while parallel-aligned slash increases both the work- and fuel-efficiency of the disc trencher. We therefore recommend operators to use less aggressive settings when disc trenching among slash, but also to become more active in monitoring their work quality. Foresters can further increase disc trenching efficiency by prescribing the trenches parallel to slash alignment and/or in seasoned slash; however, such prescriptions must be balanced with potentially longer rotation periods and added costs to harvesting, machine relocation, and tree planting.