Precision Agriculture, 3, 135–154, 2002
© 2002 Kluwer Academic Publishers. Manufactured in The Netherlands.
Grain Yield Mapping: Yield Sensing,
Yield Reconstruction, and Errors
Graduate Student, Agricultural and Biosystems Engineering (ABE), Iowa State University, Ames, Iowa
THOMAS S. COLVIN email@example.com
Agricultural Engineer, USDA-Agricultural Research Service, Ames, Iowa
Abstract. Research ﬁndings are reviewed focusing on yield sensing methods, yield reconstruction, mapping,
and errors. Yield sensing methods were explained and yield mapping process was brieﬂy introduced. Grain ﬂow
through different combines was explained and the effects of combine dynamics on yield measurement accuracy
were discussed. Other errors caused by various sensors that are utilized by a yield monitor were included. It
was concluded that with proper installation, calibration, and operation ofyield monitors, sufﬁcient accuracy can
be achieved in yield measurements to make site-speciﬁc decisions. Nevertheless, attention must be paid when
interpreting yield maps since yield measurement accuracy can vary depending upon the measurement principle,
combine grain ﬂow model, size ofmanagement area chosen, and the operator’s capabilities and carefulness in
following instructions to obtain the best accuracy possible under varying ﬁeld operating conditions. Some of
the errors can be ﬁltered out by careful analysis of the raw yield (or ﬂow rate) data provided by yield monitors.
Researchers have focused on crop ﬂow models to improve yield reconstruction process. A yield reconstruction
algorithm that effectively handles non-linear combine dynamics has not been developed by researchers yet.
More efforts towards yield reconstruction should be encouraged.
Keywords: precision agriculture, yield map, yield reconstruction, yield monitor, error
The motivation for site-speciﬁc farming and the function of yield mapping within site-
speciﬁc farm management practices have been addressed by early researchers (Bae et al.,
1987; Borgelt and Sudduth, 1992; Colvin et al., 1991; Klemme et al., 1992: Schueller,
1991; Searcy et al., 1989; Stafford et al., 1991). Yield maps provide feedback information
on how crops respond to certain soil and crop management practices and are used to
determine recommendation rates for many inputs (Dingemans, 1997; Birrell et al., 1996).
Crop yield is used as an important integrator ofvarying crop and soil variables, such as
nutrients, moisture, and pest problems (Vansichen and De Baerdemaeker, 1991; Sudduth
et al., 1997). This establishes the grounds for managing farmlands based on crop and
A detailed evaluation ofyield mapping has been done including the deﬁnition of
the yield map, components ofyield mapping technology, errors in yield mapping, and
yield mapping analysis and interpretation (Blackmore and Marshall, 1996; Pierce et al.,
1997; Blackmore and Moore, 1999). The objective ofthis review paper was to compile
signiﬁcant research results on yield sensing methods, yield reconstruction, yield mapping