An initial look at the texture, pH and conductivity data

Note that the texture values for clay, silt and sand are the percent of the soil mass less than 1mm.
The proportion of soil between 5-2mm and 2-1mm is a percentage of the soil mass less than 5mm.

Texture

Summary statistics of texture data from Malvern and manual sieving. The texture values for clay, silt and sand are the percent of the soil mass less than 1mm. The proportion of soil between 5-2mm and 2-1mm is a percentage of the soil mass less than 5mm. Units are percentage
Category Size_um avg max min sd
Clay 0.02 - 3.99 2.629718 9.998822 0.0000000 2.227363
Silt 3.99 - 63.25 20.442973 66.647455 2.8944420 12.738825
Total sand 63.25 - 126.19 66.524108 94.064129 10.7946970 17.522712
Very fine sand 126.19 - 152.79 10.403202 19.644248 3.0414290 3.828432
Medium sand 152.79 - 502.38 13.389233 33.281450 0.6632710 5.142493
Coarse sand 502.38 - 1002.37 26.852856 45.037645 0.8212990 10.078490
Very coarse sand 1002.37 - 2000 16.111232 61.250830 0.0000000 11.190065
Between 1-2mm 8.603699 22.319767 0.4959088 3.332215
Between 2-5mm 11.241832 42.575782 1.4877263 5.683067

The texture data doesn’t look very normal, which could be problematic for kriging.

Let’s look at the distribution of the texture variables across the plots

Clay %

Silt %

Sand %

Conductivity and pH

Variable avg sd min max
Conductivity (mS) 3.373133 2.172126 0.08 10.63
pH H2O 6.075733 1.671046 3.32 9.93
pH KCl 5.502733 1.642818 3.10 8.70

The relationship between ph(H2O) and ph(KCl) deteriorates at high values. This is probably because the pH meter was much less stable at high pH than low pH.

Conductivity doesn’t seem to have a clear pattern with pH, except that low pH tends to have low conductivity.

Spatially, conductivity doesn’t have very strong trends. But pH correlates well with colour: http://rpubs.com/Chopin/384267

Conductivity mS

pH H2O

pH KCl