Productivity and Characterization of Biomass Obtained from Pruning of Walnut Orchards in Mexico

Walnut tree (Carya illinoensis (Wangenh.) K. Koch) is a plant species showing ecological, social, and economic importance in Mexico. The objective was to determine biomass productivity and to characterize the raw material and biomass briquettes obtained from walnut thinning pruning. The variables evaluated were tree total height (TH), fresh biomass (FB) and dry biomass (DB) per hectare (kg ha(-1)). Briquettes were made by using the biomass obtained in both orchards. Laboratory tests for original biomass included moisture content (MC), ash content (AC), volatile matter (VM) and fixed carbon (FC), as well as high heating value (HHV). Briquette studies also included diameter (D), weight (W), length (L), volume (V), density (Ds), and HHV. The data were analyzed by using descriptive statistics and analysis of variance (ANOVA) under a completely randomized design with factorial arrangement. Thinning pruning in walnut orchards provides 12 kg tree(-1) (998 kg ha(-1)) of dry biomass, with acceptable levels of AC <= 5%, FC (75 to 76%), VM (18.7 to 19.7%) and HHV (16.2 to 16.7 MJ kg(-1)). The briquette international quality standards were fulfilled: MC <= 10%, AC <= 5% and HHV > 18 MJ kg(-1). The integrated use of walnut residues reduces the management problems registered during nut production and the sustainable options to generate bioenergy will be expanded.