Improved Water Quality through Water Table Management in Eastern Canada

Abstract

A two-year field study was conducted in eastern Ontario to evaluate the effects of water table management on the quality of subsurface drain flows. Drainage discharge volumes and NO3--N concentrations in drainage effluent were monitored during the growing seasons. The 3.5 ha experimental field was strip-cropped with corn (Zea mays L.) and soybean (Glycine max Merr.). Controlled-drainage subirrigation was used to manage water from precipitation and subirrigation. The two controlled water table treatments were 50 cm and 75 cm from the surface. There was also a conventional free-drainage treatment (FD). In 1995, mean NO3--N concentrations in drainage water were reduced by 84% and 75% by the 50 and 75 cm controlled water table depths, respectively. In 1996, drain flow volumes and NO3--N concentrations were significantly reduced relative to free drainage. Total drain flow was reduced by 42% by the 50 cm controlled water table, while NO3--N concentrations were reduced by 61% and 52% by the 50 cm and 75 cm contr...