Comparison of different mulch materials in a tomato (Solanum lycopersicum L.) crop

Black polyethylene as mulch is the most extended material among vegetable growers; however, photodegradable and biodegradable films have appeared as an alternative to conventional mulches due to the risk of the progressive contamination of soils. Reflective materials reflect back most of the incoming solar radiation, being recommended in areas characterized by high soil temperatures. We compared the effect of three mulches, black polyethylene, black biodegradable corn starch plastic and aluminized photodegradable plastic on a tomato crop in an open field.We measured mulch deterioration, soil temperature under mulches, tomato yield and fruit quality attributes (total soluble solids, firmness, dry weight, juice content and shape). Biodegradable mulch performed its function successfully and disappeared visually from the soil about three months after the crop was finished. Photodegradable mulch deteriorated prematurely and polyethylene film was practically intact at the end of season. Significant differences in mean soil temperature under mulches were observed (27.8ºC in biodegradable, 28.7ºC in aluminized and 31.8ºC in polyethylene), although they did not have a marked effect on the crop yield. Marketable yields were similar in both biodegradable and polyethylene mulches (9.82 and 8.66 kg m-2, respectively), and higher than those recorded in aluminized photodegradable mulch (6.85 kg m-2), which resulted in the highest sunscald in fruits. No effect on the fruit quality attributes was observed. Biodegradable plastic mulches could be a good alternative to the traditional plastic films, and aluminized photodegradable mulches seem not very advisable because they reduce marketable yield and could increase the incidence of sunscald.