Three component-based bi-layer and ecofriendly mulching films.

Abstract

Among the agronomic practices usually employed to achieve more successful culture results, mulching (M) has been applied using a variety of materials. In particular, the employment of plastic M films has made a revolution since they offer an evapotranspiration decrease whereas the soil temperature is also controlled, thus leading to an earlier crop maturation. Additionally, pests are more easily controlled, as well as both the possible soil erosion and farming products lose due to rainfalls are minimized. Then, less herbicides and pesticides use, and a more efficient employment of water resources is achieved. As a result of this, M improves the soils organic and nutritional characteristics even though investing fewer resources than in traditional culturing. However, although plastic M has multiple benefits, some negative impacts are also associated with this farming implement. Since most plastic mulches are non-biodegradable and non-reusable, there is a necessity to remove them from the fields, and further stockpile, transport or even burn them. In the present research work bi-layer M films (Figure 1a) were prepared through simple and low-cost procedures from biodegradable, natural and renewable resources, minimizing the employment of both energy and auxiliary substances. Thus, the global objective was to straightforwardly improve agronomical practices by introducing the use of materials complying with the green chemistry, green engineering and circular economy principles. For this, poly-lactic acid (PLA), sulfated cellulose nanocrystals (S-CNC) and chitosan (CH) were employed as starting materials to develop a bi-layer eco-friendly system composed by a top hydrophobic layer (PLA) and an interior hydrophilic one (S-CNC:CH). The hydrophilic layer was prepared by forming polyelectrolyte complexes (PEC). CH was included to offer anti-microbial and elicitor capabilities.