Polyethylene mulch and glazing create optimal conditions for soil solarization

07/01/2015

To achieve solarization, solar radiation is used to heat the moist soil covered with plastic covers, in order to increase the temperature of the soil to the point where it is lethal for soil pathogens. The effectiveness of solarization is based on the actual maximum temperature reached, and the amount of time these high temperatures can be sustained.

According to the authors of a study published in HortScience, the semiarid climate of southern Arizona is ideal for the use of soil solarization. Ursula Schuch, advisor to the former graduate student Kristen Hanson pointed out that June is the ideal time for solarization in the region because the radiation and temperatures are higher than in any other month of the year. The low relative humidity of the early summer months combined with high temperatures and high solar radiation, provides an ideal opportunity for the use of solarization in high tunnels while the production beds are fallow.

Schuch, Hanson, and specialist researcher Tilak Mahato designed experiments to determine the effectiveness of using clear polyethylene mulch on the soil surface inside tall tunnels covered with clear polyethylene glazing to solarize the soil during the warmer time of the year. "UThe objective of the study was to provide information to farmers in the semi-arid southwestern region that could be beneficial for the protection of their crops of weeds and other pests"Said Schuch.

The experiments were carried out in two high tunnels in Tucson. Polyethylene glazing was maintained over the tunnels from the end of May to the beginning of June. Half of each of the culture beds was covered with clear polyethylene mulch that contained an ultraviolet stabilizer that prevented its degradation due to solar radiation.

"We found that the most effective solarization strategy was to maintain the glazing over the tunnels together with a cover of 25,4 mm of polyethylene on the beds before watering them", Wrote the authors. "When the daily solar radiation averaged about 29,8 MJ * m², and outdoor temperatures reached 38 ° C, soil at 5 cm depth exceeded 45 and 55 ° C for almost 15 and 8 hours respectively. This treatment resulted during a significant period, when the temperatures exceeded the thresholds for the elimination of pathogens, pests and weeds, in a relatively short period" In the experiments, soil temperatures at 15 cm were increased in such a way that the disinfection of many unwanted organisms was completed in less than 1 week.

The authors added that achieving solarization with polyethylene mulch without the glazing over the tunnels would require more time to achieve the desired effects. The results also managed to determine that only solarization with glazing in the higher tunnels were less effective in raising the soil temperature.

Source: eurekalert.org