%0 Journal Article %T Corn Hybrid Response to Water Management Practices on Claypan Soil %A Kelly A. Nelson %A Randall L. Smoot %J International Journal of Agronomy %D 2012 %I Hindawi Publishing Corporation %R 10.1155/2012/925408 %X A study evaluated corn (Zea mays L.) hybrids (Asgrow785, DKC61-73, DKC63-42, LG2642, and Kruger2114) and water management systems (nondrained, nonirrigated (NDNI); drained, nonirrigated (DNI) with subsurface drain tiles 6.1 and 12.2ˋm apart; drained plus subirrigated (DSI) with tiles 6.1 and 12.2ˋm apart; nondrained, overhead irrigated (NDOHI)) on yields, plant population, and grain quality from 2008 to 2010. Precipitation during this study was 36 to 283ˋmm above the past decade. Planting date was delayed 18ˋd in the nondrained control in 2009, and additional delayed planting controls were included this year. Grain yields were similar in the 6.1- and 12.2ˋm-spaced DNI and DSI systems in 2008 and 2010, but plant population increased 74% and yields were 3.1ˋMg haˋ1 greater with DSI at a 6.1ˋm spacing compared to 12.2ˋm in 2009. At a 6.1ˋm spacing, DNI or DSI increased yield 1.1 to 6.6ˋMg haˋ1 (10 to over 50%) compared to NDNI or NDOHI soil. High yielding hybrids achieved similar yields with DNI, while NDNI DKC63-42 had 1.2ˋMg haˋ1 greater yields compared to DKC61-73. A 6.1ˋm spacing for DNI claypan soils is recommended for high yielding corn production. 1. Introduction Within-season climate variability is a primary factor affecting corn yields in Missouri [1]. Although Midwestern farmers have been planting up to two weeks earlier than in the 1980s [2], recommendations for initiating planting continue to be based on field conditions and soil temperature [3]. Soils that are cool and wet can delay planting. Adequate soil drainage helps soils dry and warm quickly. The distribution of rainfall in upstate Missouri generally peaks in mid-April to mid-May, with periods of drought and little water available to plants in late June, July, and early August [4每7]. Drought conditions during July and August are usually yield limiting in claypan soils, due to their low water-holding capacity [1, 4, 8]. However, these soils* poor drainage may contribute to excessive yield loss, due to stand loss, fertilizer loss, and poor root development [4, 6, 8每10]. Several studies have evaluated corn response to drainage water management systems [11每14], interactions between drainage and nitrogen management [15每17], and the impacts of drainage on water quality [18每21]. Other studies have evaluated the effects of drainage and overhead irrigation on yield response of corn in a claypan soil in Southern Illinois [22每24]. Corn yields synergistically increased 4.8ˋMgˋhaˋ1 with overhead irrigation and subsurface drainage [24]. In dry years, drainage plus subirrigation increased 3-year %U http://www.hindawi.com/journals/ija/2012/925408/