In the last years the use of plastic films for agricultural soils mulching and for low tunnels -in particular based on polyethylene (PE) and ethylene-vinylacetate copolymers (EVA)- has shown an increasing diffusion. In Italy the plastics employed for these purposes cover an area of more than 100.000 hectares with an annual consumption of about 65.000 tons that, for the vast majority (about 80%) are abandoned on the soil or burnt without control by the farmers, with a consequent emission of severe pollutants in the atmosphere and in the soil. Such tendency, so dangerous from the ecological point of view, is particularly diffused for mulching and direct soil contact films which, being dirty and contaminated by diserbants and fertilizers at the end of their useful lifetime, are not interesting for recycling operations. As matter of fact, while the recovery of used plastics from greenhouses and high tunnels is slowly approaching the targets imposed by law (75 % to be recycled within 2005), in the case of low tunnel and mulching films recycling is still to take-off. Moreover, in the last years a new practice, plastic solarization, has been introduced to avoid the use of fumigants such as methyl bromide, banned by the european legislation since 2005. These plastics are joining mulching films and they are not recyclable as well.
The first serious attempt to solve the problem has been carried out by NOVAMONT, Italy, which produced a starch based film, Mater Bi, initially designed for shoppers and hence, also with the help of ICTP, has been reconsidered and formulated for agricultural applications. Agronomic results were satisfactory with costs, for some cultures, even competitive in comparison with polyethylene, if one takes into consideration cost savings for disposal and for the possibility to use films of reduced thicknesses. Nevertheless, for some applications, the higher investment costs for biodegradable mulching films can represent a serious constrain for their commercial success on large scale. How can costs be diminished? An aspect to be optimized might be the production process costs that, for materials from renewable resources, sometimes require a step of physical or chemical modification of natural substances in view of rendering them processable on the same lines used for polyolefins. Such processes might increase the costs and impact in an unsustainable manner on the raw materials price. On the above thematic is based the project BIOCOAGRI (LIFE Environment 03/377), approved by the European Community on September 2003, coordinated by the Institute of Chemistry and Technology of Polymers (ICTP) (Dr. Mario Malinconico, First Researcher), with the participation of Cybernetic Institute "E. Caianello" in Pozzuoli, the University of Naples "Federico II", University of Bari, University of Osnabrueck in Germany, PSS Industry in Sweden. The project develops a sustainable approach in which a waterborne solution of natual polymers (polysaccharides of marine and terrestrial origin) is obtained and sprayed on a agricultural soil to form a film resistant for the time required for the specific application (from few weeks for solarization to few months for mulching). The process starts with the proper blending of natural polymers and additives so to obtain a sort of varnish.
For comparison, films based on polyethylene and films based on starch, supplied by Polyeur (Benevento) and Novamont (Novara), are tested too.
BIOCOAGRI Project is still in progress. On the basis of some preliminary results, The University of St. Andrews, in Scotland, has awarded Dr. Malinconico a prize for environmental technology, in the frame of an international competition to which hundreds of projects attended from all over the world.
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