Figure 1. Prairie landscape (Photo by Flickr user PRSSS Photos)

Figure 2. Soil Profile (Photo by Flickr user PRSSS Photos)

July 12, 2012. Site two was located in an agricultural area near the town of Rolla.  The field had been planted in forage crops and rejuvenated periodically for stand health.  Our pit was located just beyond the edge of the cultivated zone and contained a variety of grasses.  The Ah₁ horizon was a silty clay loam enriched with organic matter from decaying grass roots.  Medium and strong granular coarse structures were present.  While moist, the soil was black (10 YR 2/1); the dry colour was very dark greyish brown (10 YR 3/2).  A smooth, gradual boundary led to the clay loam Ah₂ horizon below which had the same medium and strong granular coarse structures.  The colour of this horizon was less intense; moist it was dark brown (10 YR 2/2) while dry it was grey (10 YR 5/1).

Figure 3. Secondary structure from Bn horizon (Photo by Flickr user PRSSS Photos)

Below the next smooth, clear boundary was the silty clay loam Bn horizon.  We found strong, medium prismatic primary structures that broke into medium strong fine subangular blocky peds (Figure 3).  When moist, the Bn horizon was very dark brown (10 YR 2/2) that dried to a dark greyish brown (10 YR 4/2).  No clay films, slickensides or effervescence was present in either of the A horizons or the Bn. A smooth, diffuse boundary led to the clay Bt horizon composed of medium strong coarse subangular blocky structures.  The colour was very dark grey (10 YR 3/1) when moist and very dark greyish brown (10 YR 3/2) when dry.  Many medium thick clay films could be found pore spaces and on the horizontal and vertical ped faces.  Weak effervescence was present in this horizon.  Fine roots could be found between the prismatic structures.  A smooth, diffuse boundary led into the Ckss horizon which also had a clay texture.  The structure was massive.  When moist, the soil in this horizon was dark grey (10 YR 3/1); we did not obtain a dry sample to colour.  No clay films were present in the Ckss, but strong effervescence was apparent in this horizon.  In addition, we observed slickensides while excavating the pit, seen as large slabs of soil breaking loose with sheared horizontal faces.

While laboratory data would be required to confirm that the sodium content and electrical conductivity are within the required range for the Bn designation, the prismatic structure combined with the visual evidence of salts indicated by the pale colour of the soil when dry suggests that this horizon does contain an accumulation of sodium.  Based on our field observations, we classified this soil as a Vertic Black Chernozem.