1Dept. of Soil, Environmental and Atmospheric Sciences, Univ. of Missouri, Columbia, MO 65211.
2Div. of Plant Sciences, Univ. of Missouri, Novelty, MO 63460.
Poorly drained claypan soils can increase the importance of tillage and N
management for corn (Zea mays L.) production. Field research in 2008, 2009 and
2010 (high rainfall years) near Novelty, MO (40° 1' N, 92° 11' W) sought to
determine the effect of polymer-coated urea (PCU) placement [strip-tillage (ST) deep
banded and no-till (NT) broadcast] and application timing (fall, early preplant and
preplant) on red clover (Trifolium pratense L.) biomass and corn response compared
to non-coated urea (NCU) and anhydrous ammonia (AA) in the presence and
absence of nitrapyrin a nitrification inhibitor. Strip-tillage reduced clover dry weights
20% in 2008 and 2009 and early preplant ST reduced dry weights 40 to 45% in 2010
compared to NT. Corn plant population was 8,100 to 8,400 plants ha-1 greater with
ST compared to NT. Preplant applications of AA plus nitrapyrin, AA, ST placement
of PCU and NCU increased grain yields 1 to 1.2 Mg ha-1 compared to fall
applications of these fertilizer sources. Fall and preplant ST placement of PCU
increased grain yields 1.2 Mg ha-1 compared to NCU. Strip-till placement of PCU
and NCU increased yields 2.1 to 3.2 Mg ha-1 over broadcast applications of these
fertilizer sources. Strip-till placement of PCU synergistically increased yield over
NCU and broadcast applications of PCU or NCU due to increased stands and
possibly due to better plant utilization of the banded N fertilizer utility.