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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS

Location: Agricultural Systems Research Unit

Title: Phosphorus lateral movement through subsoil to subsurface tile drains

Authors
item Allen, Brett
item Mallarino, Antonio -
item Lore, John -
item Baker, James -
item Haq, Mazhar -

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 18, 2011
Publication Date: March 1, 2012
Repository URL: http://handle.nal.usda.gov/10113/57106
Citation: Allen, B.L., Mallarino, A.P., Lore, J.F., Baker, J.L., Haq, M.U. 2012. Phosphorus lateral movement through subsoil to subsurface tile drains. Soil Science Society of America Journal. 76(2):710-717.

Interpretive Summary: Little research has focused on lateral P transport to tile drains. A replicated field study investigated the lateral movement of a solution of P and a Br- tracer through 3.0 m of typical Iowa subsoil (sandy loam texture, pH 7.7, 2 mg kg-1 Olsen P). Tile drainage data indicated that 83-90% of Br- tracer reached the tile. However, only 0.4-1.5% of P reached the tile. Soil P measured in vertical and horizontal samples taken from subsoil showed that background P increased only in the 0.3 m of subsoil closest to where the P solution was introduced. For example, Olsen P and Bray P were 49 and 60 mg kg-1, respectively, and both tests decreased asymptotically to a 2 mg kg-1 background P level. Results indicate that P-deficient sandy loam subsoil can greatly retard the lateral movement of P from a highly concentrated solution toward tile drains, presumably by precipitation and/or adsorption.

Technical Abstract: Vertical subsurface P transport to tile drains is well documented, however little research has focused on lateral P transport. A replicated field study investigated the lateral movement of P through 3.0 m of typical Iowa subsoil (sandy loam texture, pH 7.7, 2 mg kg-1 Olsen P) between a 1.2-m deep trench and a 1.2-m deep tile line. Once the inflow rate of water added to the trench equaled tile water outflow, a solution containing 8.7 mg L-1 P and 98 mg L-1 Br- was added to the trench to maintain it to a 0.6 m depth for 25 days. Tile drainage data indicated that most Br- reached the tile, as maximum Br- concentrations were 83-97 mg L-1 across replications. However, little P reached the tile because the maximum P concentration was 0.035-0.13 mg L-1. Soil P was measured in numerous samples taken from subsoil (0.61-1.22 m depth) located between the trench and the drainage tile after draining the trench and allowing it to dry. Background P was increased only in the 0.3 m of subsoil closest to the trench wall. For example, Olsen P and Bray P were 49 and 60 mg kg-1, respectively, and both tests decreased asymptotically to a 2 mg kg-1 background P level. Results indicate that P-deficient sandy loam subsoil can greatly retard the lateral movement of P from a highly concentrated solution toward tile drains, presumably by precipitation and/or adsorption.

Last Modified: 8/19/2014
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