HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Heathman, G. C. Articles by Johnsen, K. E. Search for Related Content PubMed Articles by Heathman, G. C. Articles by Johnsen, K. E. Agricola Articles by Heathman, G. C. Articles by Johnsen, K. E.

Surface Aggregates and Macropore Effects on Chemical Transport in Soil under Rainfall

USDA-ARS, National Agricultural Water Quality Lab., Durant, OK 74702

D. J. Timlin

Systems Research Lab., Beltsville, MD 20705

L. R. Ahuja^* and K. E. Johnsen

Great Plains Systems Research, Fort Collins, CO 80522

*Corresponding author (ahuja{at}gpsrvl.gpsr.colostate.edu).

ABSTRACT

Soil surface aggregates and macropores have the potential to greatly influence the transport of surface-applied agricultural chemicals in soil and to surface and groundwater. We studied the effects of a 1.0-cm layer of 4.5- to 12.5-mm surface aggregates, a 3-mm artificial macropore, and their combination on the transport of surface-applied Br^– and Sr²⁺ tracers (as SrBr₂) under simulated rainfall, with the underlying soil initially dry or prewetted to a certain depth (about 7 cm). Air-dried Kirkland soil (fine, mixed, thermic Udertic Paleustoll), <3.5-mm size, was packed in duplicate 15-cm-diam., 30-cm-long, sectionable Plexiglas columns (Cole-Parmer Instrument Co., Niles, IL) to a bulk density of 1.26 Mg m^–3. During the rainfall, surface runoff or macropore flow out of the column bottom was measured and analyzed for Br^– and Sr²⁺. After the rain, the column was sectioned in 1.15-cm increments to determine soil water, Br^–, and Sr²⁺ content distributions. Without a macropore, the surface aggregates reduced the overall movement of Br^– in soil and increased Br^– in runoff, the effects being much greater in prewetted columns than in nonprewetted columns. A macropore, by itself, also reduced the movement of the main Br^– pulse as it allowed surface solution (runoff) to move down and infiltrate laterally below the main wetting front. Surface aggregates greatly increased Br^– content of the macropore flow and of the wetted soil around the macropore below the main wetting front. Aggregates or the initial condition did not change the Sr²⁺ movement much but increased Sr²⁺ content of runoff or macropore flow.

Received for publication May 23, 1994.

This article has been cited by other articles:

				T. M. Nissen and M. M. Wander Management and Soil-Quality Effects on Fertilizer-Use Efficiency and Leaching Soil Sci. Soc. Am. J., September 1, 2003; 67(5): 1524 - 1532. [Abstract] [Full Text] [PDF]

				C. M. Rostagno and R. E. Sosebee Biosolids Application in the Chihuahuan Desert: Effects on Runoff Water Quality J. Environ. Qual., January 1, 2001; 30(1): 160 - 170. [Abstract] [Full Text]

				M. Ghodrati, M. Chendorain, and Y.J. Chang Characterization of Macropore Flow Mechanisms in Soil by Means of a Split Macropore Column Soil Sci. Soc. Am. J., September 1, 1999; 63(5): 1093 - 1101. [Abstract] [Full Text]