# Evaluation of Autonomous Mowers Weed Control Effect in Globe Artichoke Field
## 4 Discussion
A similar trend was observed for the estimated effective time to move the 50 and 80% of the area. Significant differences emerged only between AM2 and AM1 according to which AM2 required less time than AM1 to move the 50% and 80% of the area, with a difference of 19.081 and 44.304 min, respectively. The total primary energy consumption estimated in accordance with the chosen work schedule was lowest for AM1, and highest for AM3, while AM2 obtained an intermediate value. This parameter was significantly influenced by the power consumption during mowing of each autonomous mower type. However, AM1, due to the lower work capacity than the other two autonomous mowers, required the greater number of machines to comply with the work schedule. This involves a greater waste of time for the installation of charging bases and boundary wires of each autonomous mower, and for the machines management and maintenance. Based on the results obtained, AM2 was considered the best compromise among the three autonomous mowers tested for weed control in the artichoke field. Indeed, this machine proved to be a little more performing, and capable of reaching the target coverage of 80% in less time than AM1. The use of AM2 in artichoke crop cycle means that fewer machines are needed to comply with the chosen work schedule compared to the other autonomous mowers tested, which results in time saving. Furthermore, the total primary energy consumption is lower than AM3. Nevertheless, the test was conducted on a well-leveled and not sloping field. In a more challenging agricultural scenario, AM3, being equipped with four-wheel drive, may be more suitable [25]. Regarding the comparison between the two weed management systems, the higher average weed height in plots managed with flail mower was linked to its lower frequency of moving. The autonomous mower, on the other hand, due to its higher moving frequency was able to maintain a weed height close to the height of the cutting disc. During May and June, weeds showed a greater cover percentage than in April, as the abundant rainfall in the second decade of April together with the increase in temperatures favored weed growth in the following months. Autonomous mower weed management achieved the lower weed cover percentage. Probably, autonomous mowers' high moving frequency may have contributed to reduce weed weed production as reported by [PERSON] [50], limiting the spread of these. Furthermore, a lower above-ground biomass was found in plots managed by the autonomous mower, which usually results in less competition with the crop [51]. This finding may confirm the efficiency of this type of machines for weed control [25]. Moreover, despite the use of the autonomous mower involves a longer working time, the primary energy consumption was lower compared to the flail mower. According to [PERSON] et al. [52], the lower energy consumption of the autonomous mower with respect to a gasoline mower could be linked to its low power required to perform moving, also due to the tendency to cut only small clippings due to the higher moving frequency. Overall, the efficiency of the battery powered autonomous mower is higher compared to the gasoline mower. Indeed, considering the efficiency of the brushless motor (90%), the charging efficiency of Li-ion batteries (91%), and the Italian National Electricity System (0.562), the overall efficiency of the autonomous mower is equivalent to 0.46, while that of a small gasoline engine ranges from 0.20 to 0.25 [53]. In addition, battery powered mowers are able to adjust the energy consumption depending on mowing load, in order to maintain the blade rpm constant. On the other hand, gasoline mowers usually work at full throttle, and this consequently can result in a partial waste of power [44]. This result suggested that the autonomous mower weed management system might be more sustainable than the considered conventional system. Furthermore, the second trial showed that there were no differences about the globe arichoke yield between the two systems.