Building Sustainability and Profitability in Vegetable Production through Plastic Mulch Management

Abstract

Plastic mulch films are widely implemented in horticultural production systems around the world due to the films facilitating increased yields. Due to their common use, concerns have begun to arise about the long-term sustainability of intense plastic mulch use. Two potential ways to alleviate any ill-effects of long-term, intense plastic mulch use are replacing the fossil-based plastic mulches with biobased and biodegradable plastic mulches or using the same layer of plastic mulch for multiple cropping seasons. The use of biodegradable mulches has gained traction in several countries, and many studies using biodegradable mulches have been done in the United States. Multi-season use of plastic mulch film has become a common practice in the Southeast US. This project is an investigation into biodegradable plastics in comparison to conventional plastic, and the multi-season use of plastic mulch films in comparison to a single season of use. Biodegradable mulch films are not currently equivalent to regular plastic mulches, in regard to their material characteristics such as their mechanical properties and durability. Both of the biodegradable films were less effective at weed control than the plastic films, which all research articles read prior to this study beginning foreshadowed. Neither of the biodegradable films used in this study remained well enough intact to use for more than one season, and all four mechanical properties tested were generally lesser for biodegradable mulches than for the plastic mulches. Despite their material inequalities, the biodegradable films produced similar total yields to plastic films in two of the three seasons. The mulch with the highest net revenue was Conventional at $21,027.23 per acre and the mulch with the lowest net revenue was FilmOrganic at $15,527.55 per acre. The observed difference in revenues is at least partially due to the biodegradable mulches being more expensive materials as well as their lower durability which led to them being replaced at the beginning of each growing season. Both plastic mulches included in this study would be acceptable choices for a mulching material to leave in place over multiple growing seasons. However, the longer a mulch is left in place, the higher the soil compaction becomes, which in turn contributes to lower soil moisture and lower yields - both of which were observed in this study. The decrease in gross revenues observed between Season 1 and Season 3 for Conventional ($12,694.50 per acre) and Solar Shrink ($8,757.50 per acre) suggest that in a multi-cropping system, mulch films should not be left in place for a third or even more subsequent seasons at the risk of low net revenues for the later seasons. The amount of residual plastic mulch recovered from the field increased from 0.03 ft2 to 7.01 ft2 from Season 1 to Season 3, which illustrates the potential of increasing negative environmental impacts when using the same layer of plastic mulch film for multiple seasons.