Agronomic Spatial Variability and Resolution Data Normalization and Temporal Variability

Agronomic Spatial Variability

and Resolution

Data Normalization

and

Temporal Variability

Data Normalization

• Frequently, measurements made at different locations or at the same location at different times differ in magnitude because of other factors. For example yield varies because:– rainfall differs between years or locations– Different crop cultivars (varieties) are used– Freezes occur at flowering– Different rates of fertilizer are applied

Data Normalization

• Data normalization adjusts the measured variable to a common scale to reduce biases when making comparisons.

• Data are normalized by dividing each measurement by the average value of all measurements or dividing all measurements by the maximum value.– Dividing by the mean yields an average value

of 1– Dividing by the maximum yields a maximum

value of 1

Data Normalization

• Generally, measurements should be normalized, when making multitemporal comparisons– This is particularly important when

investigating spatial variability


• Agronomic measurements can change over time with measurements changing at different rates within a field during a growing season.

• This variability is termed temporal variability.

• Measurements can also change differently within a field between crop years.

• This variability is frequently termed multi-temporal variability.


• Temporal variability may be described by:– Time series analysis– Descriptive statistics

Temporal Variability Field Average Yield Year P. Creek East P. Creek West Cherokee

1991 18.3 20.1 23

1992 32.2 29.6 41

1993 29.2 26.7 44

1994 37.5 18.4 40

1996 20.3 18.8 35

1997 46.9 67.2 52.1

1998 52.4 56.6 63.6

Mean 33.8 33.9 42.7

Median 32.2 26.7 41.0

Coef. Var. 37.7 58.4 30.0

Satellite Estimated Satellite Estimated YieldsYields

Temporal Variability By Temporal Variability By FieldField

Red Rock, OklahomaRed Rock, Oklahoma




Pond Creek, OklahomaPond Creek, Oklahoma




Cherokee, OklahomaCherokee, Oklahoma




Hitchcock, OklahomaHitchcock, OklahomaEast FieldEast Field

Hitchcock, OklahomaHitchcock, Oklahoma East FieldEast Field

Hitchcock, Oklahoma Hitchcock, Oklahoma East FieldEast Field

Hitchcock, OklahomaHitchcock, OklahomaEast FieldEast Field

Hitchcock, OklahomaHitchcock, OklahomaWest FieldWest Field

94 yield12-2424-3333-4141-4747-59




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Agronomic Spatial Variability and Resolution Data Normalization and Temporal Variability