Soil steaming to disinfect barnyardgrass-infested soil masses

Abstract

Reusing soil can reduce environmental impacts associated with obtaining natural fresh soil during road construction and analogous activities. However, the movement and reuse of soils can spread numerous plant diseases and pests, including propagules of weeds and invasive alien plant species. To avoid spread of barnyardgrass in reused soil, its seeds must be killed before that soil is spread to new areas. We investigated the possibility of thermal control of barnyardgrass seeds using a prototype of a stationary soil steaming device. Four Norwegian and one Polish seed population were examined for thermal sensitivity. To mimic a natural range in seed moisture content, dried seeds were moistened for 0, 12, 24 or 48 h before steaming. To find effective soil temperatures and whether exposure duration is important, we tested target soil temperatures in the range 60 to 99 C at an exposure duration of 90 s (experiment 1) and exposure durations of 30, 90 or 180 s with a target temperature of 99 C (experiment 2). In a third experiment we tested exposure durations of 90, 180 and 540 s at 99 C (experiment 3). Obtaining target temperatures was challenging. For target temperatures of 60, 70, 80 and 99 C, the actual temperatures obtained were 59 to 69, 74 to 76, 77 to 83 and 94 to 99 C, respectively. After steaming treatments, seed germination was followed for 28 days in a greenhouse. Maximum soil temperature affected seed germination, but exposure duration did not. Seed pre-moistening was of influence but varied among temperatures and populations. The relationships between maximum soil temperature and seed germination were described by a common dose-response function. Seed germination was reduced by 50% when the maximum soil temperature reached 62 to 68 C and 90% at 76 to 86 C. For total weed control, 94 C was required in four populations, whereas 79 C was sufficient in one Norwegian population.

Laser weeding: opportunities and challenges for couch grass (Elymus repens (L.) Gould) control

“…IWM can potentially reduce the environmental impact of individual weed management practices and reduce the selection pressure of herbicide resistance 7 . Mechanical weeding is widely used in organic crop production, but there are many other methods which can reduce the selection pressure for herbicide resistance, such as electric weeding 8 , steaming 9 , and flaming 10 . Furthermore, small autonomous weeding robots have been developed to replace tractors and compensate for the lack of agricultural labor power 11 , 12 .…”

An integrated weed management approach in tomato using soil steaming, mulching, and winter cover crops

“…It has traditionally been used as a fumigant replacement in ornamentals and horticultural crops where some chemicals are not permitted (Fennimore and Goodhue, 2016;Baldoin et al, 2010). Soil steaming is shown to reduce weed seed germination by 50% at 62-68°C and 90% at 76-86°C (Bitarafan et al, 2022). Also, high temperatures damage plant membranes, resulting in cellular damage (Monteiro and Santos, 2022;Samtani et al, 2011;.…”

“…Also, high temperatures damage plant membranes, resulting in cellular damage (Monteiro and Santos, 2022;Samtani et al, 2011;. According to Bitarafan et al (2022), no germination occurred in soil steaming with a target temperature of 99°C at 90, 180, or 540 s. A study on strawberry (Fragaria ×ananassa) production reported that steaming soil at 70°C for 20 min provides similar weed control efficacy as methyl bromide and chloropicrin treatments (Samtani et al, 2011).…”