Tuesday, November 14, 2006 - 3:15 PM

Drainage and Subirrigation of Claypan Soils.

Kelly Nelson, Matthew Jones, and Randall Smoot. Univ. of Missouri, PO Box 126, Novelty, MO 63460

Economic situations have caused several farmers to re-evaluate production systems that maximize yield and maintain environmental sustainability. Agricultural drainage is not a new concept; however, utilizing drainage as part of an integrated water management system is a relatively new concept that has been shown to improve water quality and sustain agricultural viability. Upland, flat claypan soils commonly have a seasonal perched water table from November to May, which is caused by an impermeable underlying clay layer that restricts internal drainage yet may be useful for subirrigation purposes. Research from 2001 to 2005 was initiated to determine the suitability of claypan soils for drainage and a drainage/subirrigation (DSI) water-level management system, and evaluate the effect of the systems on corn and soybean grain yield at different drain tile spacings compared to non-drained claypan soil. Drainage only (DO) increased average corn grain yields up to 17% while DSI increased average yields up to 38% when compared with non-drained, non-irrigated soil. Overhead irrigation increased grain yield 20% compared to subirrigated corn with 6 m laterals when averaged over all N treatments in 2004 and 2005.  However, applied water was 10 times greater for overhead irrigated corn during this period.  Soybean planting date was delayed an average of 5 days in the non-drained control when compared with drained soils. Soybean grain yield with DO averaged 20% greater than the non-drained or non-drained delayed planting controls while DSI increased yields 25% when compared to the non-drained or non-drained delayed planting controls.