Frequency Analysis of Yield for Delineating
Yield Response Zones*
D. F. HEERMANN AND
M. K. BRODAHL
USDA-ARS Water Management Unit, 2150 Centre Avenue, Building D, Suite 320, Fort Collins, CO 80526
Abstract. The yield in any given ﬁeld or management zone is a product of interaction between many soil
properties and production inputs. Therefore, multi-year yield maps may give better insight into deter-
mining potential management zones. This research was conducted to develop a methodology to delineate
yield response zones by using two-state frequency analysis conducted on yield maps for 3 years on two
commercial corn ﬁelds near Wiggins, Colorado. A zone was identiﬁed by the number of years that yield
was equal and greater than the average yield in a given year. Classes producing statistically similar yield
were combined resulting in three potential yield zones. Results indicated that the variability of yield over
time and space could successfully be assessed at the same time without the drawbacks of averaging data
from diﬀerent years. Frequency analysis of multi-year yield data could be an eﬀective way to establish
yield response zones. Seventeen percent of the ﬁeld #1 consistently produced lower yield than the mean
while 43% of the ﬁeld produced yield over the mean. Corresponding values for ﬁeld #2 were 6% and 42%.
The remainder of the ﬁelds produced ﬂuctuating yields between years. These spatially and temporally
sound yield response maps could be used to identify the yield-limiting factors in zones where yield is either
low or ﬂuctuating. Yield response maps could also be helpful to delineate potential management zones
with the help of resource zones such as electrical conductivity and soil maps, along with the directed soil
Keywords: two-state frequency analysis, management zones, yield response zones, corn
Variable rate application of agricultural inputs to crop requires well-deﬁned nutrient
management zones—a part of a ﬁeld with similar nutrient supplying capabilities.
Moore and Wolcott (2000) stated that management zones for production ﬁelds
might lead to increased eﬃciency in application of inputs based on yield.
Management zones can be created by either qualitative data such as bare soil color
or quantitative data such as soil electrical conductivity or soil organic matter.
Employing these soil variables for delineating management zones by themselves may
lead to overlooking the interactions between these variables and the environment
that drives the ﬁnal yield. As stressed by Staﬀord et al. (1999), gathering information
on the interactions is possible, but is time and labor intensive.
*Mention of trademark or vendor does not constitute a guarantee or warranty of the product by the
USDA and does not imply any exclusion of other products or vendors that may also be suitable.
Precision Agriculture, 5, 435–444, 2004
Ó 2004 Kluwer Academic Publishers. Manufactured in The Netherlands.