Spatial Response of Corn Yields to Drainage and Subirrigation Tile Spacings in a Claypan Soil

Abstract

Abstract. Poorly drained claypan soils are common in Northeast Missouri. Subsurface tile drainage systems used in conjunction with water-level control structures for subirrigation have impacted corn (Zea mays L.) yields in the region. The objective of this research was to evaluate yield variability and plant population of two subsurface drain tile spacings (6.1 and 12.2 m) at 3.05 m intervals from the tile lines for a claypan soil. We analyzed 42 year-hybrid-nitrogen management systems from 2002 to 2015 near Bethel, Missouri at 6.1 and 12.2 m drainage tile spacings (DO) and drainage tile spacings with sub-irrigation (DSI). Yields and plant populations were determined at 3.05 m intervals above and between the 6.1 and 12.2 m tile lines, and were compared to non-drained (ND) and non-drained delayed planting (NDDP) controls. For all data, average yields increased 27% (2.01 Mg/ha) with DO at a 6.1 m spacing compared to the non-drained controlled. DSI at a 6.1 m spacing increased yields 38% (2.77 Mg/ha) compared the non-drained control. Yields were evaluated by low ( 12.58 Mg/ha) yield sites to better understand variability among systems and spacings. In a low yield environment, yields above a 6.1 m spaced tile line were 74% greater than between the tile lines, while yields above the tile lines were three times greater than the ND control. Grain yield variability generally decreased from a low-medium yielding to a high yielding environment. Narrower drain tile spacings may need to be installed to reduce grain yield variability in low to medium yielding environments, but the cost-effectiveness of these systems needs to be determined.