Search

The pappi of cardoon ( Cynara cardunculus L.) flowers form a crown of plumose filaments which aid the wind dispersal of the seeds connected to them. The high cellulose content of this fraction can be a valuable raw material for fiber or pulp products. During threshing, the pappi are discharged together with the other biomass, but as they are liable to blow away, they fly away during discharging and from the windrow. As the biomass is baled within 3–4 h after harvesting, the objective of the study was to test a wetting system applied to a combine and the effect of some adjuvant in limiting pappi dispersal caused by the wind. The system included a water tank (1 m 3 ), an electric pump, a flow regulator, and three pairs of nozzles to spray the solution onto the threshed material discharged from the rear of the combine. Four adjuvants in two concentrations were used to extend the retention time. The percentage of retention was evaluated on an artificial surface (plastic panels) and on the crop residues left in the windrows behind the combine. The retention time analysis was made one (T1) and four hours (T4) after harvesting. On the plastic panels, the pappi treated just with water showed a low level of sticking because the covered area had decreased by 92.9% at T1 compared to the time of harvesting (T0). The amount of pappi remaining on the windrow at T4 proved the efficacy of one of the adjuvants (AL-02) in limiting dispersal (52.8 kg ha −1 ), bearing in mind that without wetting (untreated), the amount remaining was seven times less (7.51 kg ha −1 ). Therefore, wetting appears a feasible option, compared to no treatment, to keep a certain amount of pappi on the soil. In order to reduce the dispersal and to increase the recovery of the pappi, the combine (equipped with the wetting system) should be rapidly followed by a baler, before the wetting effect disappears.

Cardoon ( Cynara cardunculus L.) is a promising crop for utilizing marginal lands. In these terrains, the lack of adequate tillage or soil levelling and the excessive presence of stones requires a high cutting height during harvesting, with remarkable biomass loss occurring. CREA-ING designed a new flexible bar driven by a system for sensing and signalling the presence of obstacles during the forward of motion of a combine harvester. A test-track was prepared to monitor the activation sequence of three sensor systems placed on the cutter bar as follows: four piston transducers measuring the flexion of the blade and counter-blade, two opposite wire transducers computing the movements of the blade-holder hinged on the left and right side of the frame, and one wire transducer placed between the head and the combine for measuring the lifting of the head operated by the hydraulic system. The combine was driven at an average speed of 0.7 km h −1 on a row of progressively higher obstacles (from 10 to 40 cm) placed in lateral, intermediate and central positions. The tests were carried out in the left half of the cutter bar. The output sent by the different sensors varied as a function of their position and the position of the obstacle, thus highlighting that the presence of an obstacle was correctly perceived by the sensor system. The signals originated from the left and right transducers had opposite trends. At the narrow “bell-shape” showed by the graph of the left transducer corresponded to a “reversed” bell generated by the right transducer, thus representing graphically the flexibility of the bar. The four piston transducers detected the necessary flexion, then lift and return the cutter bar to the starting point in response to each obstacle. The head lifting varied from 1.25 s to 2.51 s, but a threshold value could be observed as follows: below 25 cm the lifting occurred between 1.0 s and 1.5 s, while for higher obstacles the head lifting required 2.0–2.5 s. Such movement was the result of the signals sent by the sensors to the control unit before the head lifting began. The difference between the input sent by the transducers and the head lifting ranged from 1.22 s to 2.54 s in relation to the position of the obstacle. The tests showed that the head elements activated efficiently during the overcoming of an obstacle. However, if increasing speeds are needed, the reduction of Δ Act or D sig will require a modification of the electrohydraulic components.

The exploitation of energy crops requires the assessment of their sustainability in terms of both economic and environmental cost. Among the agronomic practices applied for giant reed ( Arundo donax L.) production, harvesting may weigh for a relative high percentage on the overall balance. Till now, conventional and modified machinery have been used for the production of different type of biomass (shredded, chipped, baled). In the present study an economic and energy analysis of harvesting systems and biomass transport has been conducted considering three actual cases of study representative of common harvesting systems in Italy and Spain: single-pass (chipping and loading) and two passes (mowing plus chipping and loading or crushing and windrowing plus baling). The aim of the work was to evaluate the cost-effectiveness and the environmental sustainability of the different options. The number of operations (single or two passes) did not weigh on the final result, and the economic criterion did not coincide with the energy one. The cost of harvesting for the single-pass system was the lowest (17.9 € t dm −1 ), but the economic costs of the whole chain (harvesting and transport) were more convenient for baling, and the energy demand of both systems was similar. Evidence was provided that factors like type of machinery, effective field capacity, yield, moisture content, bulk density and crop uniformity influenced the harvesting costs (from both economic and energy viewpoints) and the delivery of the biomass from the field to the first collection point. Therefore, a case-by-case analysis is recommended in order to optimize the logistics of a particular bioenergy plant.

Arundo donax L. has received much attention from researchers as biomass crop because of its vigorous growth, high productivity and low agronomic inputs requirements. Once harvested, the chopped biomass of A. donax L. may be stored for a variable period according to energy demand or logistic reasons. As consequence of storage, the chopped biomass may undergo processes of degradation that can compromise the energy yield of the product and the economic convenience of the cultivation. In the view of preserving the A. donax L. biomass for producing different kind of energy, such as bio-ethanol, biogas, and fuel for combustion, the aim of this study was to investigate, in small-scale, different storage systems assessing the dynamics of storage and their effects on energy losses and fuel quality. The work has included different studies, such as (i) the monitoring of heat development, moisture content and dry matter losses, (ii) the analysis of polymeric compounds and combustion performances. Results indicate that according to the storage method adopted, the conservation of the product can be significantly influenced, with clear impacts on its energy potential. Polymeric composition changed after storage according to the method used, while energetic characteristics were not remarkably affected.

The harvesting of wood species intended for energy production is one of the critical steps for the establishment of an economically viable supply chain. The review examines the state of the art of the main systems for collecting the short rotation coppice (SRC) by referring to poplar (Populus spp.), one of the main energy species for southern Europe. Starting from the early experiences of willow (Salix spp.) in Sweden, over time two approaches have established: the cut-and-chip and the harvest-and-storage system. In the work, the pros and cons of the two systems are analyzed and their efficiency compared, giving also some indication about the next evolution of the machines. Emerging systems showing an interesting future potential as bales production or the development of small-scale tractor-powered harvesters are also described. Finally, some economic considerations on differences between harvesting cost for the cut-and-chip and harvest-and-storage system are reported.

About two thousand species of plants are known in the world to yield natural fibers, but just a few are commercially important, providing nearly 90% of the global production of natural fibers. Since ancient times, humans required fiber to produce cordage, tools, clothes, nets, etc., in order to provide food and shelter. Among the most productive fiber plants, the bast fiber crops are undoubtedly considered as major contributors. The bast fibers are sclerenchyma fibers associated with the phloem of crops such as flax, hemp, kenaf, ramie, nettle, jute, etc. Currently, in both Europe and China, bast fibers are used for industrial applications in textile, construction, automotive, and other industries. Recently, bast fibers gained importance also as a renewable feedstock for the production of strong, lightweight, composite materials. However, there are factors in agro-industrial chain that limit the broad commercialization of these crops and their products. From an agronomical point of view, a part of the problems are associated with technological gaps in harvesting technologies, which impede the full exploitation of some crops. For instance, the production of high-quality fibers for textile firstly depends on the quality of the raw material, which in turn is linked, among the others, with the efficiency of the harvesting system adopted. In most cases, these systems were developed locally, based on available solutions in connection with specific local agricultural practice. The aim of this paper is to present a review of the existing mechanical harvesting systems for bast fiber crops in Europe and China, with special reference to hemp, flax, and kenaf. In addition, the work will furnish a description of the innovations that have been adopted in recent years to improve the harvesting processes in order to increase the value of these crops and their products.