Solar heating of the soil: effect on weed control and on soil-incorporated herbicides.
Solar heating (SH) of the soil by mulching it with transparent polyethylene during the hot season of 1979 and 1980 at Rehovot and Berurim, Israel, elevated the soil temp. by 10-18°C above that of non-mulched soil. SH for 4-5 wk effectively controlled most summer and winter annuals for 5 months except for Melilotus sulcatus, Malva nicaeensis and Astragalus boeticus. Vegetatively propagated perennial weeds such as Cyperus rotundus required 8-10 wk mulching for effective control. Use of perforated, shaded or black sheeting reduced weed control but not significantly. Use of soil-incorporated EPTC or vernolate with SH did not improve weed control over SH alone but it enhanced herbicide degradation. However, SH inhibited fluridone disappearance while the residual phytotoxicity of bromacil did not change. Mulching either with or without EPTC or vernolate increased yields of wheat and turnips but not of parsley; fluridone killed wheat and turnips, but not parsley, in both mulched and unmulched plots.