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Jacob P. Vossenkemper
Department of Plant and Soil Sciences
Oklahoma State University
Problems (Booth, 2009) estimated that each spring
391 million dollars in nitrogen fertilizer is flushed down the Mississippi River
Additionally (Malakoff 1998) estimated 700 million dollars annually
Currently NUE is 33% for cereal grain production worldwide (Raun and Johnson, 1999)
Nitrogen fertilizer is one of the most costly inputs in agriculture production today
Solutions
RotationsForage production systemsGenetically modified hybridsFoliar applied nitrogenPrecision agriculture approaches
(application resolution)
Precision Agriculture Approaches Traditionally midseason fertilizer
applications in corn (Zea maize L.) are placed down the center of 76 (cm) rows
Advent of precision agriculture technologies allows producers to place midseason nitrogen closer to the plantRTK ( Real Time Kinematics) correction
signal Auto track Auto steer
Objectives
To evaluate midseason (V8 to V10) variable liquid UAN (Urea Ammonium Nitrate) rates (45, 90, and 134 kg/ha) applied at different distances (0, 10, 20, and 30 cm) from the center of the row
Currently evaluating planting distances (10, 20, and 30 cm) away from preplant UAN applied in continuous bands
76.2 (cm)Row
0 (cm)Directly on the brace roots
10 (cm)From
the Row
76.2 (cm)Row
20 (cm)From the
Row
76.2 (cm)Row
30 (cm)From the
Row
76.2 (cm)Row
Application Methodology
UAN applied in a continuous stream
Application Methodology
Previous Work A three year study by Vyn and West (2008) from
Purdue University found that planting corn using RTK guidance systems 12.7 (cm) (five inches) from the preplant N band using UAN generally improved corn yields
An ongoing collaborative project at Oklahoma State University involving Bio-systems and Agricultural Engineering, has shown that planting corn using RTK guidance systems 15.24 (cm) (six inches) from the pre-plant band of UAN generally improved corn yields in a dry-land production system.
Previous Work Shoup and Janssen in 2009 found that in extremely
wet conditions planting closer to nitrogen bands may be beneficial.
However, planting closer to pre-plant nitrogen in normal conditions proved to have little effect on grain yield (Shoup and Janssen, 2009: Agronomy e-update 191, Kansas State Ext Pub)
In a study conducted at Oklahoma State University midseason applications of nitrogen (V8 to V10) were applied to every other row. Rows that did not have midseason applications (V8 to V10) had lower yields (Edmonds, 2007).
Previous Work This study provides evidence that mass flow of nitrate in
semi-arid to arid climates may not be substantial enough to move midseason N great distances in a single growing season on a micro-scale (0 to 76 cm).
LCB Irrigated Treatment Structure 2008
Randomized Block Design
Plots six (m) by four rows
Harvested middle two rows
Port silt-loam
LCB Irrigated Treatment Structure 2009
Added three high rate (224 kg/ha) treatments
Randomized Block Design
Plots six (m) by four rows Harvested middle two rows
Port silt-loam
76.2 (cm)Row
13 (cm)Directly on stalk of plant
76.2 (cm)Row
0 (cm)Directly on the brace roots
38 (cm)Down
the Center of the Row
76.2 (cm)Row
45 kg N/ha applied preplant, excluding checkSED =
LCB Irrigated Added Treatments 2009
Haskell Dry-land Treatment Structure 2008
No data as of yet
Trial still in the field
Conclusions Research suggests that under
irrigated conditions in a silt-loam soil Midseason N rates of 45 (kg/ha) applied at the
base of the plant 0 (cm) were better than middle of the row
Closer applied midseason N rates ranging from 90 to 224 (kg/ha) may or may not be beneficial
N applied at the base at high rates showed no evidence of being detrimental to yield