Effect of subsurface drainage, crop rotation, and tillage on crop yield in Fargo clay soil

Subsurface drainage has recently become common for agriculturally productive clay soils in the Northern Great Plains of United States. However, evidence-based recommendations regarding best combinations of drainage, tillage, and crop rotation are lacking on these frigid clay soils. Therefore, a four-year (2014 to 2017) study was conducted in the Red River Valley of eastern North Dakota to evaluate the effects of subsurface drainage (i.e., conventional drainage [OT], controlled drainage [CD], and no drainage [check]), crop rotation (i.e., continuous corn [Lea mays L.; CC] and corn-soybean [Opine max (L.} Merr.; CS] rotation), and tillage (i.e., chisel plow [CH], no-till [NT], and strip till [ST]) on crop yields. Drainage, crop rotation, tillage, and their interactions significantly affected corn yields during 2014 to 2017. Corn yield was similar between drainage treatments except during 2014 and 2015 when no drainage yielded 22% and 8% higher, respectively, than drained treatments. Corn in rotation (CS) produced 28%, 53%, and 8% significantly higher yields than CC in 2015, 2016, and 2017, respectively.The CH corn yielded 12%, 9%, and 8% significantly higher than other tillage treatments in 2014, 2016, and 2017. However, ST yielded 5% significantly higher in 2015 than NT Among all drainage, tillage, and crop rotation combinations, the four-year corn yield average was significantly highest for the no drainage, CH, and CS combination (10.98 Mg ha(-1) [163.42 bu ac(-1)]). Drainage and tillage did not affect soybean yields throughout the study, except during the drought year of 2017 when CH averaged across all drainage treatments and CH in combination with no drainage yielded 18% higher than all other treatments (4.5 Mg ha(-1) [66.97 bu ac(-1)]).