Marco Manzone

The harvesting of low-value trees, primarily utilized for energy production, demands heightened productivity and reduced costs, necessitating the adoption of mechanized methods. Excavators are frequently employed in mechanized harvesting due to their affordability (often being used machines) and high adaptability. However, their operation often results in tree damage when swinging the upper structure. Consequently, recent advancements have led to the development and utilization of machines with smaller footprints, primarily applied in urban settings, aiming to enhance maneuverability.This study aimed to analyze the operational and environmental benefits of employing reduced-tail swing excavators in forestry operations in contrast to conventional tail swing excavators. In thinning operations, the productivity of the reduced-tail swing excavator surpasses that of the conventional tail swing excavator by 18.5%, accompanied by a 41.8% reduction in fuel consumption. Moreover, the reduced-tail swing excavator exhibits a 41% decrease in energy consumption, resulting in a notable 65.8% reduction in CO2 emissions compared to its conventional counterpart. Additionally, the hourly operational cost is 10% lower than that of the conventional tail excavator.While comparing the performance of both machines in clear-cutting, the differences observed are less than 5% and deemed statistically insignificant. Hence, it can be inferred that reduced-tail swing excavators present a viable alternative to conventional-tail excavators.

Maize silage is one of the most used feedstock for the anaerobic digestion plants in Italy. As biomass, it is necessary to choose maize hybrids and sowing times to reach the maturity stage at the planned harvest period. In addition, the contractor has to set up transport chains considering distances and other factors affecting the forward speed in function of the supplied biogas plants. This work examined different road conditions (length, weather and congestion) that might influence the maize silage transportation under both the energy and economic points of view. Tests were carried out with an agricultural tractor equipped with two trailers (a turntable steering and a dumper) along six itineraries (6.2, 15.3, 22.1, 32.5, 44.4, and 58.2 km) in two different traffic conditions: high congestion (early morning) and low congestion (evening). Tests were also performed in two seasons with different weather conditions: late Summer and early Autumn. The average forward speed was 27.40 km h–1 with a 15% difference between the best (evening and late Summer) and the worst (early morning and early Autumn) condition, with a productivity that varied between 9.50 and 81.98 m3h–1 respectively. The performed tests confirmed that the energetic evaluation is always positive also in the longest itinerary (58.2 km), but the actual market value of maize silage (52.00 € t–1) limits the convenience of the transportation distance up to 18 km. In conclusion, the study showed that the maize silage transportation using agricultural tractors not only depends on the travelled distance, but also on the road congestion and the weather conditions.

Farm tractors are still widely used in many forestry operations. Predicting fuel and lubricant costs is difficult because their consumption depends on a number of factors such as hours worked and operations performed. Fuel and lubricant consumption is important since it can have an impact at both the economic and environmental level. Many fuel models have been studied in the last decades, but few studies have focused on oil consumption. The ASABE (American Society of Agricultural and Biological Engineers) Standard suggested a model for predicting engine oil consumption of farm tractors of the 1980s, which are potentially different from modern tractor engines. In addition, the recent widespread application of semi- and full-power-shift and continuous variable transmissions and the high number of hydraulic applications increased the amount of lubrication oil for transmission and hydraulic systems.For these reasons, we analysed 133 4WD recent model farm tractors used in forest operations with the aim to study:Þ engine, transmission and hydraulic system oil capacitiesÞ engine oil change intervals as recommended by the manufacturers.A new equation for engine oil consumption, as a function of the rated engine power, was first used and statistically analysed. It was similar to the equation developed by other authors (with a mean difference of 28%, decreasing to 11% at the highest engine power), but well below the ASABE model (with an average engine oil consumption three times higher). Another equation of total oil consumption related to the rated engine power was then studied and compared with a recent study. The results showed an average difference of 18%, decreasing to 8% at the highest engine power. The differences, due to a different machine dataset (only 4WD farm tractors that can be used for forestry operations were analysed) are, however, minimal also in the engine oil consumption model if compared with the oldest ones: a new proposal is therefore necessary, with new and affordable models for correctly evaluating economic and environmental forestry operation costs when using farm tractors.