Harvesting of southern Piedmont’s orchards pruning residues: evaluations of biomass production and harvesting losses

Abstract

In recent years, there has been an increasing interest in respect to all farming residues, including orchard pruning residues. The masses and dimensional characteristics of branches pruned, depend on several factors such as fruit variety, active strength plant, training systems, intensity and periodicity pruning. Many studies were done to fix this type of biomass availability, however they’re not up-to-date, and usually they are lacking of accurate surveys. A detailed knowledge of current pruning biomass availability, both qualitative and quantitative, is also necessary for the evaluation of the economic sustainability of their energetic exploitation. In this context, in order to provide an assessment of the real chain potential of energy renewable production, from Cuneo territory pruning residues, a research was conducted on two different orchards species Actinidia (Kiwi tree) and Malus (Apple tree) pruned in two different ways: “traditional system” and “taille longue system”. For each species, pruning residues amount were quantified together with their diameter. The surveys were performed at least on four half trees placed on the same row spacing with three randomized replications in the crop. The amount of pruning residues were determined by a dynamometer (precision 0.02N) whereas the diameter of individual cut-off branches has been detected at the base of the same using a twentieths calliper. Subsequently were performed pruning residues windrowing by rotating rake and the harvest of the same by fixed chamber round baler suitably modified. At the end of these operations have been determined harvesting losses with the same methodology used for the initial quantification of residues. The first result shows that with the “traditional pruning system” the biomass average availability is of 2.5t DM ha–1 and 3.0t DM ha–1, respectively for kiwi tree and apple tree. For the latter, the average values are significantly lower 0.5t DM ha–1 with “taille longue” pruning system. The harvesting losses have been nearly 19% in kiwi tree and 16% for apple tree (from 95% to 11% according to the variety). In both crops the variation of harvester losses are due mainly to the size and conformation (straight) of pruned branches.