At physiological maturity, the crop was harvested using a
combine equipped with a yield monitor and a differentially
corrected GPS. Yield monitor data were cleaned to remove
erroneous pixels and, to minimize errors associated with “lag,”
a five-pixel sliding average was used (Pierce and Novak, 1999).
Yield data were subsampled using a sample size of n 5 40
within each management zone (Hornung et al., 2003). Bootstrapping
was then used to obtain grain yield variance estimates for each management zone (Efron and Tibshirani,
1993). A two-tailed t-test was used to test significant differences
in grain yield between management zones within each
delineation technique and across both techniques.
The management zone delineation techniques were evaluated
using three approaches: (i) the farmer’s approach, (ii) a
quantitative approach, and (iii) a subjective approach. The
farmer’s approach was the simplest. This approach was suggested
by the cooperating farmers, and was based on grain
yield production between the two techniques. In other words,
the cooperating farmers were interested in finding the best
technique that would result in the greatest yield from high
management zones and the lowest grain yield in the low management
zones. Hence, using the farmer’s approach, comparisons
were made for grain yields produced in each zone for the
two techniques. For example, the grain yield from the high
zone delineated using the SCMZ technique was compared
with the grain yield from the high zone delineated using the
YBMZ technique.
At physiological maturity, the crop was harvested using acombine equipped with a yield monitor and a differentiallycorrected GPS. Yield monitor data were cleaned to removeerroneous pixels and, to minimize errors associated with “lag,”a five-pixel sliding average was used (Pierce and Novak, 1999).Yield data were subsampled using a sample size of n 5 40within each management zone (Hornung et al., 2003). Bootstrappingwas then used to obtain grain yield variance estimates for each management zone (Efron and Tibshirani,1993). A two-tailed t-test was used to test significant differencesin grain yield between management zones within eachdelineation technique and across both techniques.The management zone delineation techniques were evaluatedusing three approaches: (i) the farmer’s approach, (ii) aquantitative approach, and (iii) a subjective approach. Thefarmer’s approach was the simplest. This approach was suggestedby the cooperating farmers, and was based on grainyield production between the two techniques. In other words,the cooperating farmers were interested in finding the besttechnique that would result in the greatest yield from highmanagement zones and the lowest grain yield in the low managementzones. Hence, using the farmer’s approach, comparisonswere made for grain yields produced in each zone for thetwo techniques. For example, the grain yield from the highzone delineated using the SCMZ technique was comparedwith the grain yield from the high zone delineated using theYBMZ technique.
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