New Biodegradable materials for greenhouse soil mulching

The objective of the research is to evaluate the performances of new biodegradable mulches by means of laboratory tests and a field trial. The innovative mulches are made of paper sheets coated with different biodegradable polymer mixtures: PHA/PHB, PHA/PCL, Biomass/PHB. PHA indicates a polyester of the polyhydroxyalkanoate family with medium chain length produced by the microbial conversion of waste and exhausted edible oils, poly-β-hydroxybutyrate (PHB) is a low chain length PHA commercially available, biomass is the lyophilized bacterial micro-organism containing PHA and polycaprolactone (PCL) is a commercial biodegradable polyester. The field trial was performed inside a steel-structure greenhouse in the experimental farm of the University of Catania. The considered theses were: the innovative mulches, a polyethylene (PE) film, a commercial biodegradable film corn-starch based and the bare soil. Inside the greenhouse pepper plants were grown as crop according to the good practice of cultivation. During the trial, solar radiation flux, air temperature and relative humidity were monitored outside and inside the greenhouse, while soil temperature in the experimental theses were measured at the depth of 5 cm and 15 cm below the soil surface. Furthermore, the weed growing was checked periodically. The laboratory tests were carried out on mulch samples taken in the greenhouse at regular time-interval for evaluating the decay of the different materials. The results show that the examined innovative materials could be an alternative solution to the use of traditional plastic films, even if additional improvements of the mixtures and of the manufacturing process are needed.