Miscanthus, a crop bound for energy use
A conference at the FAO on the topic of "Mobilization of woody biomass for energy and industrial use" offered an update on the technologies and projects for energy uses of crop residues and dedicated plantations. The progress of the key projects in Europe was presented
An experimental Miscanthus crop project carried out by the Gran Sasso Velino Local Action Group has defined a model of an agro-energy supply chain for the Abruzzo foothills which can be replicated on a national scale. Other than the production of biomass for energy use, miscanthus can play an important phytoextration role for the removal of dangerous elements or compounds from agricultural soil.
Think globally and act locally is a valid premise for coping with complicated and widespread problems by contributing to circumscribed initiatives.
In this spirit, the Local Action Group – Gran Sasso Velino (GAL GSV) set up the Miscanthus Project cofinanced by the European Union Rural Development Progam for the Abruzzo Region under 2007-2013 funding. The aim was to answer two priority questions pertaining to Italian farming and also to the specific conditions of sixty-five municipalities within the territory of the GAL Gran Sasso – Velino. These are: the phenomenon of abandoned rural areas, especially marginal lands, due to financial and structural problems associated mainly with local conditions; the presence of polluting elements and compounds in agricultural soil due to intensive use of fertilizers and fungicides.
With this point of view, the project which ran for two years and came to a close last June, led to experimental work on land located in the municipality of Barisciano, in the Province of L’Aquila, where a variety of the perennial Miscanthus, or silvergrass, was planted for the job of phytoremediation of the terrain with low energy input and the production of great quantities of woody-cellulose biomass.
In fact, due to its well developed root apparatus, the Miscanthus giganteus sown can capture a number of potentially toxic elements and retain them in its roots. Some heavy metals such as cadmium are not only removed from the soil but also favor the development of the crop when present in low concentrations. Thanks to its rapid growth and elevated production of photosynthetic biomass, this crop is ideal for supplying plants for conversion into energy for combustion and possibly for the production of second generation bioethanol.
The capture and concentration in the roots of elements which may be toxic and the energy use of only the parts of the plants aboveground exclude the prospect of transferring these pollutants to other areas of the environment. Moreover, the autumn translocation of nutrients from the aboveground apparatus to the rhizome, typical of perennial rhizomatous plants, reduces the uptake of nitrogen with the biomass and thus any possible NOx emissions if earmarked for combustion.
A farm (see Box pag. 70) with such essential requirements as territory, location, size, main crops, organization, infrastructure, machinery and available equipment was chosen for the experimental cultivation of these crops.
The experiment was carried out on a land area of about one hectare with a large experimental plot set aside and an indicator plot where, on a reduced scale, the characteristics of the first one were blindly reproduced. A meteorological station was put in place on the border of the macro plot which was divided into four sections of equal sizes but given different plant layouts, 2, 4, 6 and 8 plants per m² for the purpose of evaluating variations in the production of photosynthetic biomass in relation to differing densities.
Through constant monitoring of the field it was possible to gather information useful for reports for farmers as well as local administrators on the financial and environmental benefits to be brought in with the spread of this type of crop in the GAL territory. An accredited laboratory conducted chemical-physical analyses of pre/post planting soil samples and the aboveground biomass at the end of the annual cycle to provide evidence of capabilities of mitigating and the phytoremediation of contaminating chemicals present as well as indications of the intrinsic characteristics of woody-cellulose materials for possible combustion use.
Miscanthus cultivated as a crop does not require especially careful attention, which means that the machinery normally included in a farm inventory can be used (see Form below). Once the soil was prepared, plowed, harrowed and fertilized, and some 30,000 rhizomes were planted, one relief irrigation was carried out in the month of July. In the second year, the strong presence of an infestation of a specie (mainly Echium vulgare) required a number of mechanical and chemical herbicide operations.
On the basis of the results of the experiments and the setting of the studies, it can be asserted that the introduction of Miscanthus on marginal agricultural lands in the Abruzzo displayed good growth and productivity capability on deep soil with a limestone matrix and a discrete supply of nutrients – though there could be come problems in adapting to the peculiar pedoclimatic conditions. For sound cultivation of the crop, it would be timely to work synergetically with irrigation in the first phase of the development of the crop and successively mediate with nitrogen-based fertilizer in the growth phase. In these rural conditions, which feature a wealth of biodiversity, agronomic management should include low impact on the environment in operations, fertilization and plant treatment as well as for integrated control to counter pathogens and infestations. For this purpose, an integrated management system for post-emergent weeds, chemical + mechanical, was seem as a useful and efficient operational instrument to apply for risks associated with manipulating the product with respect for good farming practices.
Attention focused on the production of aboveground biomass obtained in the first two years of the trials – considering that the crop achieves greater production from the third year on – disclosed interesting values for density in unified plantings of 4 and 6 plants/m2 where the number of stalks turned out to be higher in relation to the comparative density (see Table below). In this special setting, this could mean that the capacities of Miscanthus might be significantly influenced by the number and/or the spacing of the plants in the field. In this connection, the greater density of the crop is able to limit well the phenomenon of competition with infestations. As regards the phytoextration of pollutants, analyses show a high capacity of accumulation of copper, lead, zinc and mercury in the abovebround biomass.
In conclusion, the Miscanthus Project oriented mainly on involving workers in the Abruzzo, fully met all its principle objectives through a study of an energy crop which also includes phytoextration and phytodepuration purposes. The cultivation of Miscanthus is an opportunity to enhance the value and productivity of set-aside or abandoned land, for the production with few financial resources of biomass for energy use. In this way, a development model has become reality for the concept of multi-functional farming in Abruzzo agriculture for production not connected to human and animal food products but bound for new innovative and promising market segments. The project thus identified a study case which will be able to provide an experience for duplication in real conditions in light of the strong points and weaknesses turned up by the monitoring carried out. So in the Abruzzo setting, the Miscanthus Project can be adopted for a large number of foothill areas where, needed for countering the phenomenon of abandoning lands, is the stimulation of initiatives for generating job creation, initiatives aimed especially at young enterprising people open to them.
For this reason great prominence has been given to the dissemination of the outcome of the project through publications and meetings with such stakeholders as Itabia, the Italian Biomass Association, and FederUnacoma, the Italian Agricultural Machinery Manufacturers Federation, which provided a strong contribution by presenting the initial results of the project initiative at the EIMA International Exhibition 2014 and are planning a followup for the final findings at the Agrilevante in Bari coming up October 15-18.
Matteo Monni
