Oxford soil samples
oxford.RdData: 126 soil augerings on a 100 x 100m square grid, with 6 columns and 21 rows. Grid is oriented with long axis North-north-west to South-south-east Origin of grid is South-south-east point, 100m outside grid.
Original data are part of a soil survey carried out by P.A. Burrough in 1967. The survey area is located on the chalk downlands on the Berkshire Downs in Oxfordshire, UK. Three soil profile units were recognised on the shallow Rendzina soils; these are Ia - very shallow, grey calcareous soils less than 40cm deep over chalk; Ct - shallow to moderately deep, grey-brown calcareous soils on calcareous colluvium, and Cr: deep, moderately acid, red-brown clayey soils. These soil profile classes were registered at every augering.
In addition, an independent landscape soil map was made by interpolating soil boundaries between these soil types, using information from the changes in landform. Because the soil varies over short distances, this field mapping caused some soil borings to receive a different classification from the classification based on the point data.
Also registered at each auger point were the site elevation (m), the depth to solid chalk rock (in cm) and the depth to lime in cm. Also, the percent clay content, the Munsell colour components of VALUE and CHROMA , and the lime content of the soil (as tested using HCl) were recorded for the top two soil layers (0-20cm and 20-40cm).
Samples of topsoil taken as a bulk sample within a circle of radius 2.5m around each sample point were used for the laboratory determination of Mg (ppm), OM1 %, CEC as mequ/100g air dry soil, pH, P as ppm and K (ppm).
Usage
data(oxford)Format
This data frame contains the following columns:
- PROFILE
profile number
- XCOORD
x-coordinate, field, non-projected
- YCOORD
y-coordinate, field, non-projected
- ELEV
elevation, m.
- PROFCLASS
soil class, obtained by classifying the soil profile at the sample site
- MAPCLASS
soil class, obtained by looking up the site location in the soil map
- VAL1
Munsell colour component VALUE, 0-20 cm
- CHR1
Munsell colour component CHROMA, 20-40 cm
- LIME1
Lime content (tested using HCl), 0-20 cm
- VAL2
Munsell colour component VALUE, 0-20 cm
- CHR2
Munsell colour component CHROMA, 20-40 cm
- LIME2
Lime content (tested using HCl), 20-40 cm
- DEPTHCM
soil depth, cm
- DEP2LIME
depth to lime, cm
- PCLAY1
percentage clay, 0-20 cm
- PCLAY2
percentage clay, 20-40 cm
- MG1
Magnesium content (ppm), 0-20 cm
- OM1
organic matter (%), 0-20 cm
- CEC1
CES as mequ/100g air dry soil, 0-20 cm
- PH1
pH, 0-20 cm
- PHOS1
Phosphorous, 0-20 cm, ppm
- POT1
K (potassium), 0-20 cm, ppm
References
P.A. Burrough, R.A. McDonnell, 1998. Principles of Geographical Information Systems. Oxford University Press.
Note
oxford.jpg, in the gstat package external directory (see
example below), shows an image of the soil map for the region
Examples
data(oxford)
summary(oxford)
#> PROFILE XCOORD YCOORD ELEV PROFCLASS
#> Min. : 1.00 Min. :100 Min. : 100 Min. :540.0 Cr:19
#> 1st Qu.: 32.25 1st Qu.:200 1st Qu.: 600 1st Qu.:558.0 Ct:36
#> Median : 63.50 Median :350 Median :1100 Median :573.0 Ia:71
#> Mean : 63.50 Mean :350 Mean :1100 Mean :573.6
#> 3rd Qu.: 94.75 3rd Qu.:500 3rd Qu.:1600 3rd Qu.:584.5
#> Max. :126.00 Max. :600 Max. :2100 Max. :632.0
#> MAPCLASS VAL1 CHR1 LIME1 VAL2
#> Cr:31 Min. :2.000 Min. :1.000 Min. :0.000 Min. :4.00
#> Ct:36 1st Qu.:3.000 1st Qu.:2.000 1st Qu.:1.000 1st Qu.:4.00
#> Ia:59 Median :4.000 Median :2.000 Median :4.000 Median :8.00
#> Mean :3.508 Mean :2.468 Mean :2.643 Mean :6.23
#> 3rd Qu.:4.000 3rd Qu.:3.000 3rd Qu.:4.000 3rd Qu.:8.00
#> Max. :4.000 Max. :4.000 Max. :4.000 Max. :8.00
#> CHR2 LIME2 DEPTHCM DEP2LIME PCLAY1
#> Min. :2 Min. :0.000 Min. :10.00 Min. :20.00 Min. :10.00
#> 1st Qu.:2 1st Qu.:4.000 1st Qu.:25.00 1st Qu.:20.00 1st Qu.:20.00
#> Median :2 Median :5.000 Median :36.00 Median :20.00 Median :24.50
#> Mean :3 Mean :3.889 Mean :46.25 Mean :30.32 Mean :24.44
#> 3rd Qu.:4 3rd Qu.:5.000 3rd Qu.:64.75 3rd Qu.:40.00 3rd Qu.:28.00
#> Max. :6 Max. :5.000 Max. :91.00 Max. :90.00 Max. :37.00
#> PCLAY2 MG1 OM1 CEC1
#> Min. :10.00 Min. : 19.00 Min. : 2.600 Min. : 7.00
#> 1st Qu.:10.00 1st Qu.: 44.00 1st Qu.: 4.100 1st Qu.:12.00
#> Median :10.00 Median : 72.00 Median : 5.350 Median :15.00
#> Mean :14.76 Mean : 93.53 Mean : 5.995 Mean :18.88
#> 3rd Qu.:20.00 3rd Qu.:123.25 3rd Qu.: 7.175 3rd Qu.:25.25
#> Max. :40.00 Max. :308.00 Max. :13.100 Max. :43.00
#> PH1 PHOS1 POT1
#> Min. :4.200 Min. : 1.700 Min. : 83.0
#> 1st Qu.:7.200 1st Qu.: 6.200 1st Qu.:127.0
#> Median :7.500 Median : 8.500 Median :164.0
#> Mean :7.152 Mean : 8.752 Mean :181.7
#> 3rd Qu.:7.600 3rd Qu.:10.500 3rd Qu.:194.8
#> Max. :7.700 Max. :25.000 Max. :847.0
# open the following file with a jpg viewer:
system.file("external/oxford.jpg", package="gstat")
#> [1] "/home/runner/work/_temp/Library/gstat/external/oxford.jpg"