Feasibility of Site-Speciﬁc Management of Corn
Hybrids and Plant Densities in the Great Plains
JOHN F. SHANAHAN firstname.lastname@example.org
USDA-ARS and Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68583
THOMAS A. DOERGE
Pioneer Hi-Bred International Incorporated, Johnston, IA 50131-1150
JERRY J. JOHNSON
Department of Soil and Crop Sciences, Colorado State University, Ft. Collins, CO 80523
MERLE F. VIGIL
USDA-ARS, Akron, CO 80720
Abstract. The goal of this research was to determine the potential for use of site-speciﬁc management of
corn hybrids and plant densities in dryland landscapes of the Great Plains by determining (1) within-ﬁeld
yield variation, (2) yield response of diﬀerent hybrids and plant densities to variability, and (3) landscape
attributes associated with yield variation. This work was conducted on three adjacent ﬁelds in eastern
Colorado during the 1997, -98, and -99 seasons. Treatments consisted of a combination of two hybrids
(early and late maturity) and four plant densities (24,692, 37,037, 49,382 and 61,727 plants ha
) seeded in
replicated long strips. At maturity, yield was measured with a yield-mapping combine. Nine landscape
attributes including elevation, slope, soil brightness (SB) (red, green, and blue bands of image), EC
(shallow and deep readings), pH, and soil organic matter (SOM) were also assessed. An analysis of
treatment yields and landscape data, to assess for spatial dependency, along with semi variance analysis,
and block kriging were used to produce kriged layers (10 m grids). Linear correlation and multiple linear
regression analysis were used to determine associations between kriged average yields and landscape
attributes. Yield monitor data revealed considerable variability in the three ﬁelds, with average yields
ranging from 5.43 to 6.39 mg ha
and CVs ranging from 20% to 29%. Hybrids responded similarly to
ﬁeld variation while plant densities responded diﬀerentially. Economically optimum plant densities
changed by around 5000 plants ha
between high and low-yielding ﬁeld areas, producing a potential
savings in seed costs of $6.25 ha
. Variability in yield across the three landscapes was highly associated
with landscape attributes, especially elevation and SB, with various combinations of landscape attributes
accounting for 47%,95%, and 76% of the spatial variability in grain yields for the 1997, -98, and -99 sites,
respectively. Our results suggest site-speciﬁc management of plant densities may be feasible.
Keywords: maize, spatial variability, geostatistics, variable rate planting
Abbreviations: GIS, geographical information systems; DGPS, diﬀerential global positioning system; EC
apparent electrical conductivity; SOM, soil organic matter.
Mention of commercial products and organizations in this article is solely to provide speciﬁc information.
It does not constitute endorsement by USDA-ARS over other products and organizations not mentioned.
Precision Agriculture, 5, 207–225, 2004
Ó 2004 Kluwer Academic Publishers. Manufactured in The Netherlands.