|Cook, Sabrina - UNIVERSITY OF MINNESOTA|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 2, 1996
Publication Date: N/A
Technical Abstract: Continuous soil macropores can participate in preferential transport of water and chemicals in agricultural soils. Direct measurements of continuity, however, are tedious, time consuming, and difficult. Therefore we developed a method for estimating macropore continuity. Nondisturbed soil cores were horizontally excavated by depth, and photographs were taken nof each layer. Negatives were then digitized and made into binary images. Pores with area 0.80 mm**2 (1-mm diameter circle) were analyzed for characteristics and position using NIH Image. Assuming circular macropores, trigonometric relationships were used to determine probable entry into next deeper layer, and therefore, probable connection with macropore(s) in that layer. Average amount of macropores, predicted to be continuous to the next deeper layer, ranged from 4 to 33 percent of total macroporosity, and varied with depth and tillage treatment. Estimated continuous macropores were found to be nonvertical; mean angle from horizontal ranged from 24.6 degrees to 39.6 degrees. Nonvertical macropores are expected since the predominant earthworm is Aporrectodea tuberculata, which creates meandering burrows. Estimations were reasonable and simple to perform, however, this method needs to be verified.