Current and emerging biodegradable mulch films based on polysaccharide bio-composites. A review

Since the 1940s, the introduction of plastic technology caused a true revolution in agriculture. Among the uses of plastics, mulch films have been used to improve yields and crop traits. They are useful to increase air and soil temperatures, protect plants from several agents, improve water management, reduce the growth of weeds, and, consequently, to avoid high dependence on agrochemicals. The low-density polyethylene obtained from non-renewable resources has been mainly used for this purpose due to its mechanical and barrier properties, resistance to all forms of degradation, easy processing and low cost. Unfortunately, low-density polyethylene presents several economic and environmental drawbacks related to their low biodegradability, their removal after the crop cycle and their final disposal. Hence, there is a great interest in using biodegradable mulch films to provide greater agricultural sustainability. In this review, we interpret evidence about the potential of polysaccharide-based bio-composite mulch films as a possible replacement of traditional low-density polyethylene films as well as their commercial barriers and evolution of intellectual property rights. We identified that: (1) mulch films improve their mechanical properties through the formulation of multiphase materials, reaching international standards; (2) biodegradability of bio-composite mulch films can be adjusted according to crop season; (3) bio-composite mulch films provide high yields for different crops; and (4) they are promising for the management of pests and weeds. Due to these traits, biodegradable mulch films have reported a significant increase in the number of patent protections lately. However, to the present day the lack of knowledge about bio-composite mulch films and their high costs are the main commercial limitations to their adoption for crop production systems in the field.