Soil Solarization of Onion Nursery beds with Different Polyethylene Thickness

Abstract

Soil solarization means the complete covering of wet soil to field capacity with transparent polyethylene ultraviolet film during a variable period. Due to the solar energy caught soil temperature rises damaging the seed bank of annual weeds. This technique was evaluated in onion seedlings by INIA- DIGEGRA-FAGRO in three locations during 2005-2006. In 2006-2007 and 2007-2008 the effect of solarization on weed population and seedling quality was studied using UV polyethylene films of both 35 and 80 µm thickness as compared to a non solarized control at INIA Las Brujas. Soil was covered on 12/17/06 and 12/3/07 and temperature was recorded 10 cm depth. Seedbeds 5 m long with four rows were sown with onion cv. Pantanoso del Sauce-CRS on 4/30/07 and 04/16/08. Number of weeds/m2 , weeds fresh and dry weight, length, stem diameter, fresh and dry weight of 10 seedlings, seedling health (leaf blight, Botrytis spp.), and nitrate and ammonium in the soil were evaluated after solarization. Non solarized plots had significantly more weed infestation and dry weight compared to the solarized ones, and lower levels of soil nitrate and ammonium. The non solarized control showed significantly higher infestation and dry weight of weeds compared to the solarized plots, and lower nitrate and ammonia content. Solarized treatments were healthier than the non solarized ones. There were no statistically significant differences on weed control or seedling quality between polyethylene thickness, but there were significant differences with respect to the non solarized treatment.