2018 article

EFFECT OF DRAINAGE WATER MANAGEMENT ON NITRATE NITROGEN LOSS TO TILE DRAINS IN NORTH CAROLINA

TRANSACTIONS OF THE ASABE, Vol. 61, pp. 233–244.

author keywords: Controlled drainage (CD); Corn; Drainage water; Drainage water management (DWM); Nitrate; Nitrogen; Soybean; Water quality; Wheat
Source: Web Of Science
Added: August 6, 2018

Abstract. Short-term studies have demonstrated that drainage water management (DWM), or controlled drainage (CD), can be used to substantially reduce the loss of nitrogen (N) from drained lands for a wide range of soils, crops, locations, and climates. Long-term studies on the effects of the practice are limited. This article presents results on the effects of CD on nitrate-N (NO 3 -N) losses for three crops, corn ( L.), wheat ( L.), and soybean ( [L.] Merr.), in a two-year rotation in North Carolina. Nitrate losses were measured on replicated plots under CD and conventional, or free drainage (FD), treatments for nine years between 1992 and 2012 on a tile-drained site near Plymouth, North Carolina. The site is on a Portsmouth sandy loam soil with parallel drains 22.9 m apart and 1.15 m deep. The subsurface drainage characteristics under FD were drainage intensity (DI) = 8 mm d -1 , drainage coefficient (DC) = 14 mm d -1 , and Kirkham coefficient (KC) = 18 mm d -1 . Compared to FD, CD reduced annual drainage outflow by 33% and NO 3 -N export by 30%, with an average annual reduction of 6.3 kg ha -1 year -1 . CD increased average NO 3 -N concentrations by 0.9 mg L -1 , but the difference was not significant. The reduction in NO 3 -N export observed in the CD treatment was equal to the increase in N removed by the harvested grain. The results document the effects of CD on NO 3 -N export over a wide range of weather conditions during the nine-year study. While the average 30% reduction in NO 3 -N losses in drainage water is in the midrange of that reported by previous studies for different soils and climates, this is believed to be the first time such a reduction has been attributed to the effect of CD on increasing yields and N removed in the harvested grain. Keywords: Controlled drainage (CD), Corn, Drainage water, Drainage water management (DWM), Nitrate, Nitrogen, Soybean, Water quality, Wheat.