annexc - Newmont Mining Corporation

Annex C5 – Soil Resources Supplemental Information C5 - 2
SOIL LABORATORY ANALYSES
Findings of laboratory analyses support the discussion in Sections 3, 4, and 5 of this
document and are included in this Annex as a supplement to the data previously presented.
Sampling and analytical methods, results, and findings of data validation are presented in the
2008 soil resources technical report (Geomatrix and SRI 2008).
Agronomic Parameters
Samples for agronomic analysis were collected from 16 typical profiles representing the nine
dominant series. Kobeda and Ofin were not sampled due to their very limited occurrence
within the Proposed Mining Area and expected comparability to the Bekwai and Temang
series, respectively. The objective of this sampling was to characterize the common range
of physical and chemical characteristics of the dominant series in the Proposed Mining Area.
Results of the analyses are summarized in Table C5-1.
Textures and associated physical properties were notably different across topographic
sequences and between the lower Birimian and granitic series. Within the sequences, the
middle and upper-slope series have the highest clay and coarse fragment contents. The
granitic series are more coarsely textured than similar lower Birimian series. Coarse
fragment content was variable, but generally higher for subsoil horizons and series at more
elevated landscape positions.
The water erodibility for the fine earth fraction (Kf) and whole earth fraction (Kw), which
accounts for the affects of coarse fragments, was calculated using the soil profile
descriptions and analytical results. The data show that without considering the affects of
coarse fragments, the erosion hazard is very high for many series. The armoring affects of
the coarse fragments in upland series notably reduces erosion hazard, especially in the most
vulnerable landscape positions.
Soil profiles are highly leached due to the high precipitation and long period of soil
development. Soil pH and organic matter concentrations are low and usually decline with
depth in the soil profiles. All soil series in the Proposed Mining Area are acidic, with most
pH below 5.0 standard units (s.u.). Organic matter concentrations decline precipitously
below the uppermost 15 centimeters, reflecting the high rates of biological activity. The low
organic matter content of the soil and dominance of low-activity clay resulted in low cation
exchange capacities throughout the soil survey area.
The high rate of biological activity, low organic matter, high precipitation, acidity and low
exchange capacity have resulted in low concentrations of nutrients, especially in subsoil
horizons. Although nitrogen concentrations are variable, the greatest concentrations are
found in upland series and topsoil horizons. The carbon:nitrogen ratios of the various
samples suggests that nitrogen is widely available for plant uptake in all series. In contrast,
the concentration of available phosphorus is very low in all soil types, especially the lower
Birimian series and subsoil horizons, and can be a limiting factor in plant growth. Potassium
is also likely to be limiting in most series. The lowest concentrations are found in the
subsoil of upland series, with series of granitic origin having lower concentrations than
lower Birimian series in similar landscape positions.
Akyem Gold Mining Project November 2008 FINAL EIS