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Title: Climate Impacts on Nitrate Loss in Drainage Waters from a Southern Alluvial Soil

Author
item Grigg, Brandon
item Southwick Jr, Lloyd
item Fouss, James
item Kornecki, Ted

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2003
Publication Date: 11/30/2003
Citation: Grigg, B.C., Southwick Jr, L.M., Fouss, J.L., Kornecki, T.S. 2004. Climate Impacts on Nitrate Loss in Drainage Waters from a Southern Alluvial Soil. Transactions of the American Society of Agricultural Engineers. 47(2):445-451.

Interpretive Summary: Fertilizer nitrogen transported via agricultural drainage has caused eutrophication of nearby surface waters. In the Lower Mississippi River Valley region, periods of drought are occurring more frequently,and their impacts on nutrient loss from agricultural lands to these surface waters have not been reported. We evaluated the impact of climate (rainfall)on edge-of-field nitrate loss in both normal and drought years at the Ben Hur Water Quality Site in Baton Rouge, LA. Two replicated treatments, surface drainage only (SUR) and surface drainage + deep controlled-drainage (DCD), were initiated on field plots planted to corn (Zea mays L.). After each rainfall/runoff event, we determined the volume of runoff and subsurface drainage , and analyzed these waters, to determine nitrate concentration and loss. Drainage management did not impact runoff volume or nitrate loss in runoff. Nitrate loss in runoff was impacted by climate, with a four-fold decrease in nitrate loss during drought. Conversely, the mass of nitrate loss in leachate increased two-fold during drought. Diverting subsurface drainage effluent (DCD) to suface receiving waters increased nitrate transport to these waters by 2.6 times in the normal climate, and over 10-fold during drought, compared to surface drainage only. In either climate, but particularly in drought, subsurface drainage could potentially accelerate eutrophication of receiving waters of this region. When compared to DCD, these results suggest that SUR should be the water management practice in this region, regardless of rainfall climate.

Technical Abstract: Fertilizer nitrogen transported via agricultural drainage has caused eutrophication of nearby surface waters. In the Lower Mississippi River Valley region, periods of drought are occurring more frequently. The impacts of drought on nutrient loss from agricultural lands of this region have not been reported. Field studies were conducted to evaluate the impact of climate (rainfall) on edge-of-field nitrate loss in both normal (1996) and drought (1999) periods at the Ben Hur Water Quality Site in Baton Rouge, LA. Four replicates of two treatments, surface drainage only (SUR) and surface drainage + deep controlled-drainage (DCD), were initiated on 0.21 ha plots planted to corn (Zea mays L.). After each rainfall/runoff event, we determented the volume of runoff and subsurface drainage, and analyzed for soluble nitrate concentration and loss. There were not significant treatment impacts on runoff volume and nitrate loss in runoff. Nitrate loss in runoff was impacted by climate, with a four-fold decrease in nitrate loss during the drought climate, caused by decreased volume of runoff. Conversely, the mass of nitrate loss in leachate increased two-fold during drought. Diverting subsurface drainage effluent (DCD) to surface receiving waters increased nitrate transport to these waters by 2.6 times in the normal climate, and over 10-fold during drought, compared to SUR management. In either climate, but particularly during drought, subsurface drainage could potentially accelerate eutrophication of receiving waters of this region. When compared to DCD, these results suggest that SUR should be the water management practice in this region, regardless of rainfall climate.