Effect of organic matter on soil wettability of Ustolls.
(S06-schumacher228402-poster)
Authors:
A. Eynard* - South Dakota State Univ.
T.E. Schumacher - South Dakota State Univ.
M.J. Lindstrom - USDA-ARS Morris MN D.D. Malo - South Dakota State Univ.
R.A. Kohl - South Dakota State Univ.
Abstract:
Soil wettability is important especially for dryland agriculture in climates with a dry period during the growing season. A randomized complete block experiment was conducted to identify how soil organic C content and structure affect wettability in soil samples from grasslands (grass) and from tilled fields (till). Soil organic C, plastic limit, aggregate total porosity, and wettability at 100 and 300 mm water tension were determined from samples collected at a depth of 0 - 0.2 m. Natural aggregates from till and grass were compared to soil pellets formed by remolding aggregates. At both tensions the wettability of grass treatments was significantly higher than that of till. Pellets were less wettable than natural aggregates at 300 mm tension and during initial wetting at 100 mm tension, but more wettable after wetting at 100 mm tension. Grasslands contained twice as much organic C as tilled fields (26 vs.
13 g kg-1). Organic C was linearly related to plastic limit, total porosity, and wettability of natural aggregates at 300 mm tension. At 100 mm tension organic C explained 99% of the variation in wettability of natural grass aggregates. Organic C increased the wettability of grass aggregates and stabilized natural aggregates during fast wetting. Both structure and amount of organic C contributed to aggregate stability and wettability favorable to agriculture.
Speaker Information: Thomas Schumacher, South Dakota State Univ., SDSU NPB 247A Box 2140C Plant Science Dept., Brookings, SD 57007-2141; Phone: 605-688-4502; E-mail:
Session Information: Tuesday, November 4, 2003, 2:00 PM-4:00 PM Presentation Start: 2:00 PM (Poster Board Number: 1126) Keywords: Soil structure; soil management; organic carbon; aggregation
