From the Soil Micromorphology Slide Collection

Micromorphological description Of slide: Channel--Nearly spherical to arched, smooth walled coarse macro earthworm channel. Matrix material is compacted adjacent to the walls of the void. A thin (5 pm) membrane lines the void.

Data for the horizon
Horizon sampled: Ap
Depth sampled: 0-6 cm
Physical and chemical data available: pH = 5.9, org. C = 1 .76, N = 0.17%, exch. ca = 76.8%, exch. Mg = 19.3%, exch. K = 1 .03%, exch. Na = 0.34%, total exch. cap. (cmol (p +)/kg) = 19%, clay mineralogy = hydrous mica > kaolinite > smectite
Macromorphological description of horizon: Ap (0-1 5 cm): Dark grayish brown (IOYR 412, m) sandy loam to loam; compact, fragmented to massive; slightly firm to firm; abrupt smooth boundary.
Micromorphological description Of horizon : The upper 7 cm of the Ap horizon has a mixed matrigranoidic porphyric (85%) fabric (Brewer, 1976). The fabric is highly porous near the surface. At a depth of 7-14 cm the fabric arrangement is vughy porphyric. Voids (40%) are largely metavughs (8/10) of variable size, many are mammillated.
There are a few channels (1/10) of variable size throughout and a few skew planes (1/10) are in the lower section. Excrement features make up a significant portion of the fabric arrangement (20%). Strongly welded earthworm fecal pellets (9/10) are largely concentrated in aggrotubules. Collembola (springtail) fecal pellets (1 / 10) are found as infillings in channels and vughs. There are numerous (5-10%) meso and macro organic and sesquioxidic nodules throughout.
Data for thin section
Preparation of sample: Air dry
Impregnating medium: Epoxy
Thickness of section: 30 µm
Orientation of section: Vertical
Size of section: 5 X 7 cm

Soil Classification
U.S.: Typic Cryoboralf
F.A.O.: Albic Luvisol
Canada: Orthic Gray Luvisol

Elevation: 700 m above sea level
Topography and hill slope position: Level to undulating upper slope Parent material: Till
Soil climatic data and/or soil water balance: Subhumid moisture regime and cold soil temperature class
Vegetation: Cultivated field of barley (Hordeum vulqare)

Data for 35-mm slide
Frame length: 9 mm
Light mode: Plane polarized

Brewer, R. 1976. Fabric and mineral analysis of soils. Krieger Publ. Co., Melbourne, Fl.
Bullock, P. et al. 1985 Handbook of soil thin section description. Waine Research Publications, Wolverhampton, England. Pawluk, S. 1980. Micromorphological investigations of cultivated Gray Luvisols under different management practices. Can. J. Soil Sci. 60:731-745. Source - S. Pawluk


Soil Science Society of America, 1993. A Reference slide collection for Soil Micromorphology SSSA, Madision, WI.