Stationary soil steaming to combat invasive plant species for soil relocation

Abstract

Eradication of alien invasive species in the soil with steam as an alternative to chemical fumigation may allow contaminated soil to be reused. We have investigated steam disinfestation of soil to combat invasive plant species in three experiments including different temperatures and exposure durations using a stationary soil steaming prototype device. The experiments included effects on seed germination of Lupinus polyphyllus (LUPPO), Impatiens glandulifera (IPAGL), and Avena fatua (one population from Poland AVEFA(P) and one from Norway AVEFA(N)), as well as effects on sprouting rhizome fragments of Solidago canadensis (SOOCA) and Reynoutria x bohemica (REYBO). In the first experiment (i) we tested four different soil temperatures of 64, 75, 79 and 98°C with an exposure duration of 90 s. In the second and third experiments we tested exposure durations of (ii) 30, 90 and 180 s and (iii) 90, 180 and 540 s, respectively, at 98°C. Seed pre-treatment of 14 days cooling for LUPPO and IPAGL, no seed pre-treatment and 12 h moistening for AVEFA populations, and 5 and 10 cm cutting size for REYBO were applied. Our results showed germination/sprouting was inhibited at 75°C for I. glandulifera (for 90 s) and 98°C for the other species; however, longer exposure duration was needed for L. polyphyllus. While 30 s at 98°C was enough to kill A. fatua seeds and S. canadensis and R. x bohemica rhizome fragments, 180 s exposure duration was needed to kill L. polyphyllus seeds. The results showed promising control levels of invasive plant propagules in contaminated soil by steaming, supporting the steam treatment method as a potential way of soil disinfection to avoid dispersal of invasive species.