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ARS Home » Midwest Area » Columbus, Ohio » Soil Drainage Research » Research » Publications at this Location » Publication #317735
Title: Effect of tillage on macropore flow and phosphorus transport to tile drains

Author
item Williams, Mark
item King, Kevin
item FORD III, WILLIAM
item Buda, Anthony
item Kennedy, Casey

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2016
Publication Date: 4/17/2016
Citation: Williams, M.R., King, K.W., Ford III, W.I., Buda, A.R., Kennedy, C.D. 2016. Effect of tillage on macropore flow and phosphorus transport to tile drains. Water Resources Research. 52:2868-2882.

Interpretive Summary: Elevated phosphorus (P) loadings in tile drainage water during storm events are thought to be the result of P bypassing the soil profile in cracks, earthworm burrows, and other preferential flow pathways. Agricultural management practices, such as tillage, can substantially influence water and P transport in these pathways and ultimately the amount of P delivered to the tile outlet. In this study, we quantify the effect of tillage on preferential flow and P transport in two tile-drained fields in central Ohio during seven spring storms. Monoammonium phosphate (MAP) fertilizer was broadcast on both fields. Disk tillage was used to incorporate the fertilizer on one field, while the other field remained in no-till. Study results showed that disk tillage following fertilizer application decreased P concentrations and loads in tile drain discharge compared to a no-tilled field. The effect of tillage was only temporary (<3 weeks), but P transport is often greatest during the storms immediately following fertilizer application. Thus, results suggest that incorporating surface-applied fertilizers has the potential to substantially decrease annual P loads from tile-drained fields.

Technical Abstract: Elevated phosphorus (P) concentrations in subsurface drainage water are thought to be the result of P bypassing the soil matrix via macropore flow. The objectives of this study were to quantify event water delivery to tile drains via macropore flow paths during storm events and to determine the effect of tillage practices on event water and P delivery to tile drains. Tile discharge, total dissolved P (DP) and total P (TP) concentrations, and stable oxygen and deuterium isotopic signatures were measured from two adjacent tile-drained fields in Ohio, USA during seven spring storms. Fertilizer was surface-applied to both fields and disk tillage was used to incorporate the fertilizer on one field while the other remained in no-till. Median DP concentration in tile discharge prior to fertilizer application was 0.08 mg L-1 in both fields. Following fertilizer application, median DP concentration was significantly greater in the no-tilled field (1.19 mg L-1) compared to the tilled field (0.66 mg L-1), with concentrations remaining significantly greater in the no-till field for the remainder of the monitored storms. Both DP and TP concentrations in the no-till field were significantly related to event water contributions to tile discharge, while only TP concentration was significantly related to event water in the tilled field. Event water accounted for between 26 and 69% of total tile discharge from both fields, but tillage substantially reduced maximum contributions of event water. Collectively, these results suggest that incorporating surface-applied fertilizers has the potential to substantially reduce the risk of P transport from tile-drained fields.