Solarization for Weed Control

Abstract

Solarization is a method of heating moist soil by covering it with plastic sheets to trap solar radiation. In field experiments in Israel during the summer, maximum soil temperature under plastic cover at the 5-cm depth averaged 46 to 49C. No weeds emerged under the plastic cover during solarization and weed emergence was reduced after its removal. The heating effect from solarization decreased with soil depth. Concentration of O2 in soil under plastic was similar to that in uncovered controls, but the concentration of CO2 was markedly higher than in control soil, rising up to 2.4%. Higher temperatures and better residual weed control were produced by transparent than by black plastic, with best results from thin (0.03 mm), transparent polyethylene. Under Israeli summer conditions, 2 to 4 weeks of solarization produced effective control of annual weeds that was still appreciable after 1 yr. Narrow sheets of 20 to 50 cm produced effective weed control in bands. on soil irrigated once before placing the plastic sheets, there was no need to irrigate during solarization. The response of weed species to solarization differed. Many annual weeds, both summer species such as pigweed (Amaranthus spp.) and common purslane (Portulaca oleracea L.) and winter species as henbit (Lamium amplexicaule L.) were well controlled by solarization. Broomrape (Orobanche crenata Forsk.) was controlled in one experiment. on the other hand, horseweed [Conyza canadensis (L.) Cronq.] and bull mallow (Malva niceaensis All.) were relatively resistant, and established perennials escaped the treatment.

Effect of soil solarization on corn stalk rot

“…In solarized plots mean temperature at 10 cm soil depth was observed to be 11.5 °C higher than in nonsolarized plots. This increase in soil temperature in solarized plots was normal, as has also been reported by other workers from Israel (Horowitz et al, 1983;Jacobsohn et al, 1980;Katan, 1981), California (Pullman et a1.,1981), Canada (Lazarovits et al, 1991), Mexico (Stapleton et al, 1985;Stapleton, 1991) and Pakistan (Zaki and Ghaffar, 1989). We observed that variation in temperature at different soil depths was greatly influenced by weather conditions (cloudy, sunny, rainy days with different air temperature and humidity).…”

The effect of soil temperature, moisture and nitrogen on Striga asiatica (L.) Kuntze seed germination, viability and emergence on sorghum (Sorghum bicolor L. Moench) roots under field conditions

“…Several viability tests conducted in one experiment to verify this hypothesis (data not presented) repeatedly showed that the Striga seeds were killed by the hot humid (polythene) condition. Similar effects of solar heating (solarization) were observed for many soilborne pests (Chauhan et al, 1988;Horowitz et al, 1983;Jacobsohn et al, 1980;Katan, 1981). It appears that under such a situation, the time needed for germination induction is shortened, probably due to a rapid activation of some respiratory enzymes or mobilization of reserve foods which may be exhausted in time, thus rendering the seed non-viable (Kust, 1963;Vallance, 1951).…”

“…la) and the soil was always wet because water vapor that evaporated was trapped by the polythene cover and was again precipitated on the soil surface. Higher soil moisture increases soil heat conductivity and seed sensitivity to high temperatures (Horowitz et al, 1983). Kust (1963) reported that prolonged storage of Striga seeds under hot humid conditions, similar to those observed under the polythene, killed the seeds.…”

“…Since the experiments were conducted in a striga-sick field which was under the plough for a long time, a large reservoir of Striga seed was expected to exist and incorporated in the soil profile. Because soil solarization is usually limited to <10-cm depth, where temperatures reach lethal levels (Horowitz et al, 1983), most Striga seeds buried at deeper layers may escape the solarization effect. It is very possible, therefore, that the observed Striga plants in these plots could have come from depths lower than 2-cm, where conditions were not detrimental to the seeds.…”

Control of Exotic Annual Grasses to Restore Native Forbs in Abandoned Agricultural Land

“…The most effective way to manage weeds is to manage the seedbank, removing the source of competition and reducing the need for future vegetation management and disturbance (Horowitz et al 1983; Elmore et al 1997; Swanton & Booth 2004). Methods of seedbank control include continuously mowing or disking annual grasses, but several seasons are usually required, and both timing and diligence are important factors (DiTomaso 2000; Huhta et al 2001; Wilson & Clark 2001).…”