Soil Survey and Mapping ScaleSoil Survey and Mapping Scale

•Intensity of Mapping•Map Scale

• Intensity of Mapping: Level of detail and field inspection density that is required to achieve it.

• Map Scale: Only the scale of publication

Purity/Precision of Soil MapPurity/Precision of Soil Map

• Keep in mind:

Number of field inspections increase with detail of survey.

The larger the final intended map scale, the higher the intensity of field observation per cm2 of map

Purity/Precision of Soil MapPurity/Precision of Soil Map

Remember: Increased precision may not

improve the reliability of the map.

Inspection per cm2 is not a direct reflection of accuracy.

Acceptable Number of ObservationAcceptable Number of Observation

Survey Intensity Level (SIL): Acceptable inspection intensity varies

between 0.2 to 2 inspections per cm2, depending on homogeneity of the soil.

Reliability of Soil Boundary: Intensity provide an estimate of the

reliability of identified soil parameters in delineation, not necessarily the soil boundary placement.

Types of Field StudiesTypes of Field Studies Synthesis (< 1: 1,000,000) Exploratory/Low intensity (1:100,000 to 1:1,000,000) Reconnaissance/Medium intensity

(1:25,000 to 1:100,000) Semi-detailed/High intensity (1:10,000 t0 1:25,000) Detailed/Very high intensity (<1:10,000)

Soil Intensity Level (SIL)

Nearest FAO Equivalent

Aim and Level Site Intensity and Survey Method

Synthesis Synthesis<1:1,000,000

Resource inventory Free survey of variable intensity, <1:1000 ha

Exploratory Exploratory to low intensity 1:1,000,000 to 1:100,000

Resource inventoryProject locationRegional Planning

Free survey of variable intensity, usually much < 1 per 100 ha

Reconnaissance Medium intensity1:100,000 to 1:25,000

Pre-feasibilityProject LocationRegional Planning

Free survey of variable intensity, usually < 1 per 100 ha

Semi-detailed High intensity1:25,000 to 1:20,000

Pre-feasibilityFeasibilityDevelopmentPlanning

Flexible or rigid grid, Intensity 1 per 15 to 50 ha

Detailed Very high intensity> 1:10,000

DevelopmentManagementSpecial purposeResearch plots

Rigid grid1 per 1 to 25 ha

Soil Intensity Level (SIL)

Minimum Size of Delineation

(ha)

Mapping progress rate

(Km2/month)

Density of observation

(observ./km2)

Synthesis < 5,000ha >200 < 0.05

Exploratory 50 to 5,000 >200 0.05 to 0.5

Reconnaissance 6.25 to 50 15 to 200 0.5 to 8

Semi-detailed 4 to 6.25 12 to 15 8 to 12.5

Detailed 0.25 to 1 <12 50 to 200

Soil Intensity Level (SIL)

Associated Features Preferred Scales

Represented Soil Component

Map Units5 Aerial Photos Final Maps

Synthesis Great soil groups, phases of great groups

Physiographic units/land systems

< 1:100,000 Variable

Exploratory Association of great groups or subgroups, land units of various kind

Mainly compound, potential development areas

1:50,000 to 1:100,000

Variable

Reconnaissance Associations of soil series, physiographic units

Compound and some simple units

!:50,000 to1:20,000

< 1:50,000

Semi-detailed Soil series, soil complexes and associations of soil series

Simple and compound units

1:25,000 to1:10,000

1:20,000 to1:10,000

Detailed Phases of soil series, soil series, land parameters

Mainly simple units

1:10,000 to1:5,000

1:10,000 to1:5,000