Impact of Soil Water Repellency on Seedling Emergence and Growth

Abstract

Water repellent soils do not wet spontaneously when water is applied on the surface. Water repellency may affect seedling success by decreasing available moisture contents. The objective of this study was to identify the effects of soil water repellency on seedling emergence and seedling growth, using arable soils under laboratory conditions. Two initial moisture contents, three clay levels, five organic matter levels, and one crop species were arranged in a complete randomized design with twenty replicates per treatment. Soil water repellency was estimated using water drop penetration time test and sessile drop method. Seedling emergence and seedling growth were assessed using the time taken for seedling emergence, and seedlings to reach three inches height after planting, height and dry weight of shoots and roots at seven days after the germination. Under low initial moisture condition (1/3 of field capacity; FC) clear relationship could not be detected because of several unexpected problems due to high water stress. Under high initial moisture condition (FC), time taken for the seedling em ergence and seedlings to reach 3 inches increased, whereas the shoot growth decreased, with increasing water repellency (contact angle from 20° to 100°) in samples with 0 -2 % clay. Soil water repellency did not show clear effects on root growth. The results revealed that soil water repellency has negative effect on both seedling emergence and seedling growth.