A total of 136 B-horizon
soil samples were also collected over favourable magnetic sill previously yielding up to 269 ppb Au in soil (and 800 ppb gold in rocks).
SOC storage in the total soil profiles was 1.25 Pg, of which approximately 0.41 Pg SOC was in A-horizon soils, 0.51 Pg SOC was in B-horizon
soils and 0.33 Pg SOC was in C-horizon soils.
The stratigraphy in these 10 non-garden test pits consisted of an intact non-culturally modified A-horizon, with either an underlying B-horizon
or weathering bedrock.
la) and steady-state infiltration rates (Table 1) occur above and below the ~B boundary at this site, and extensive mottling and columnar structure suggested low hydraulic conductivity in the B-horizon
. Deep placement of fertiliser at this site increased yields and reduce yield variability significantly (Adcock et al.
and C horizons, the pH was 5.5 in all but the B-horizon
where it reached
Physical and chemical properties of bulk samples of the A-horizon sand and the B-horizon
clay-rich subsoil from Coonalpyn and Bordertown, South Australia Values in parentheses represent standard deviation Soil horizon Dry bulk density % Clay % Sand (kg [m.sup.-3]) (<2 [micro]m) (20-2000 [micro]m) Coonalpyn, South Australia A-horizon sand 1551 (13) 1 97 B-horizon
1723 (21) 28 71 Bordertown, South Australia A-horizon sand 1499 (11) 2 92 B-horizon
1806 (19) 47 61 Soil horizon PH EC (dS [m.sup.-1]) (1:5 soil : water) (1:5 soil : water) Coonalpyn, South Australia A-horizon sand 6.2 0.02 B-horizon
7.1 0.04 Bordertown, South Australia A-horizon sand 6.5 0.02 B-horizon
8.4 0.18 Table 2.
Cumulative TDN loads correlated with fine sand content in the A-horizon and silt and fine sand content in the B-horizon
; TDP loads were mainly negatively correlated with clay content in the B-horizon
; TP and TSS loads had similar negative correlations with clay contents in the B-horizon
1d from STI, a cross-section of about l km length, showed a large variation in depth to B-horizon
ranging from areas with clay almost at the surface to a sandy A horizon extending down to 0.70-0.80 m.
If the discontinuity is ignored, the plot for the B-horizon
is similar to that in Fig.
Soil data for the area indicate that a strongly duplex soil profile exists, with the ratio of A-horizon to B-horizon
conductivity >1000, so the potential for local perching is high.
the occurrence of ponding on top of the B-horizon
. Consequently, these findings led to a more detailed study of the local relationships between geology, soil profile macromorphology, soil chemistry, and hydrology.