Biodegradable Covering Films for Strawberry Protected Cultivation in Mediterranean Areas

The use of plastic films for soil mulching and low tunnel covering increases the yield and quality of horticultural products, allows the market availability of products in longer period of the year, reduces water consumption and controls weeds. At the same time it has the serious drawback of large quantities of post-consumption plastic materials to be disposed. The introduction of biodegradable films, which can be degraded and buried directly in the soil at the end of their lifetime, represents a suitable solution to this problem increasing the sustainability of the agricultural production. A research was carried out in order to investigate the performance of innovative biodegradable materials in a protected cultivation of strawberry in Southern Italy. A field test was carried out at the University of Bari from September 2001 to June 2002. Different kinds of biodegradable films for soil mulching and low tunnels covering were used and compared with non biodegradable LDPE films. During the cultivation, weather conditions of the experimental site, air temperature and relative humidity under low tunnels, soil temperature and dampness under the mulching were measured and recorded by means of a data logger. Laboratory tests were carried out on the samples gathered in field in order to evaluate modifications of the radiometric properties due to the ageing. The results for low tunnel films showed higher decrease (12%) for the PAR transmissivity coefficient and lower decrease (1%) concerning the LWIR transmissivity coefficient, both appropriate for agricultural applications. Concerning the crop yield biodegradable covering films showed horticultural results comparable with traditional LDPE films. After the harvest, the soil was tilled in order to shatter the mulching biodegradable films and to sow them inducing the degradation process. Mulching residues buried in the soil biodegraded and no toxicity was found in the soil.