Subsurface Drainage Effect On Soybean Yield in Clay Soils of the Red River Valley.

The Red River Valley, located along the state border of Minnesota and North Dakota, is well known for its highly productive clay soils that provide excellent water holding capacity.  However, excess rainfall can cause these clay soils to become saturated with water.  During prolonged periods of soil saturation, soybean [Glycine max (L.) Merr.] can experience negative physical and chemical changes in the plant resulting in a yield reduction.  One method to reduce soil saturation is using subsurface (tile) drainage.  The objectives of this research were: 1) to evaluate the effect tile drainage can have on soybean plant vigor, iron deficiency chlorosis, percent canopy closure, plant height, and seed yield, and 2) to determine if foliar-applied fungicide has an effect on percent canopy closure, plant height, and seed yield.  In 2011, soybean research was conducted on a field near Fargo, ND.  The experimental design was a randomized complete block with a split-split plot arrangement and four replicates.  The main plots were tile versus no tile drainage, the subplots were with and without foliar-applied fungicide, and the sub-subplots were ten soybean cultivars.  Tile drainage significantly reduced iron chlorosis deficiency and also significantly increased soybean plant vigor, percent canopy closure, plant height, and seed yield.  The fungicide application did not significantly increase percent canopy closure, plant height, or seed yield.  Tile drainage can be a useful tool to improve soybean plant performance and production in environments with excess water.