## 3 Results and Discussion  
### Harvesting--Step 1 (Shredding) and 2 (Baling)  
At the harvest time, the crop field was uniform and without a laid out area. The plant density was \(14.2\pm 0.04\) stems m\({}^{-2}\), the average plant height was \(3.98\pm 0.09\) m, and the average diameter was \(16\pm 2\) mm. The shredding level obtainable in the different machine settings was very heterogeneous, with excessive fragmentation of herbaceous parts such as leaves and simultaneous presence of stem parts longer than 50 cm that were not or partially crushed. The working times and performance characteristics of the first step are reported in Table 2.  
The favorable conformation of the plots and the reduced time loss for logging positively influenced the performance of the machine with an effective field capacity of over \(1.1\) ha h\({}^{-1}\) for the low speed (T1 and T3) and \(1.7\) ha h\({}^{-1}\) for the high-speed treatments (T2 and T4). The same result was obtained for both high and low yield areas. The working speeds were always slightly higher than the originally set values for the treatments, because the automatic engine management system permitted different engine settings, i.e., constant speed and/or power take off (PTO) speed. For this test, the engine management was set to a constant PTO speed with a low speed variation caused by a low variation in the engine torque. Regarding the effective field capacity, the high yield obtained is \(60.70\) t ha\({}^{-1}\) and the low one is \(56\) t ha\({}^{-1}\), in terms of material capacity, at a moisture level of \(42.51\%\). After shredding, the biomass drying in the field was monitored to define the harvest date (baling). The second step was carried out when the biomass moisture was \(6.09\%\)--much less than the minimum level of \(12\)-\(14\%\) cited in reference [36]. In the feeding step, the pick-up of the harvester was able to operate efficiently, and the collection of the larger particles of the chopped yield was regular, as shown in Figure 4. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{2}{c}{**T1**} & \multicolumn{2}{c}{**T2**} & \multicolumn{2}{c}{**T3**} & \multicolumn{2}{c}{**T4**} \\ \cline{2-9}  & **Values** & **\%** & **Values** & **\%** & **Values** & **\%** & **Values** & **\%** \\ \hline Effective time (_TE_), s & 344 & 90.05 & 229 & 89.8 & 349 & 91.84 & 234 & 92.49 \\ Accessory time (_TA_), s & 38 & 9.95 & 26 & 10.2 & 31 & 8.16 & 19 & 7.51 \\ _Turning time_ (_TAV_), s & 38 & 9.95 & 26 & 10.2 & 31 & 8.16 & 19 & 7.51 \\ Total, s & 382 & 100 & 255 & 100 & 380 & 100 & 253 & 100 \\ _Effective Speed_, km h\({}^{-1}\) & 4.33 & & 6.51 & & 4.27 & & 6.37 & \\ _Operating Speed_, km h\({}^{-1}\) & 3.9 & & 5.84 & & 3.92 & & 5.89 & \\ _Effective field capacity_ & & & & & & & \\ (_EFC_), ha h\({}^{-1}\) & 1.17 & & 1.75 & & 1.18 & & 1.77 & \\ _Material capacity_, t h\({}^{-1}\) & 35.15 & & 52.66 & & 32.68 & & 49.09 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Working time and performance characteristics of the shredding phase of _Arundo donax_ harvesting. As shown in Table 3, the study of the working time demonstrated that the highest efficiency occurred when the tying time was between 14 and 30 s (because at the beginning, the number of wrappings was very low, causing some deformation of the bale). This value is increased as the number of wrappings and the turning times became uniform at 21-25 s. The speed was about 5 km h\({}^{-1}\) for T2 and T3; however, for thesis 4, it was the highest (6.55 km h\({}^{-1}\)). Regarding the round bale performance, values were fairly low, but they were still associated with a low biomass moisture content at baling time, about 7 times less moisture than that produced by cutting. During shredding (Table 4), the hourly consumption for chopping remained low for the class of tractor power adopted. However, the engine power was oversized because of the needing to have a tractor with reversible drive system.