Soil Burrowing and Mixing by a Crayfish
- E. L. Stone
Observation of rapid lateral water flow through, rather than over, the surface of a level, clayey, mixed, thermic Typic Albaquult (Bladen series) prompted study of the abundant burrows of a crayfish, Procambarus rogersi rogersi Hobbs. The area was a 20-yr-old experimental plantation of slash pine (Pinus elliottii Engelm. var. elliottii), with a wide range in tree growth, ground vegetation, and O-horizon thickness. The objective was to better understand the elaborate macropore system and its consequences for mixing the surface layers of a very poorly drained soil where other burrowing animals were lacking. Excavation of burrows and burrow casts revealed galleries, 4 to 10 cm in diameter, > 1.5 m long, chiefly in the upper 30 cm of soil but with vertical shafts to >1 m in depth. Fifty to 80% of randomly located 0.1-m2 subplots in well-forested plots had from one to five openings through the mineral soil surface into surficial burrows, demonstrating widespread distribution of the latter. Bands of rock phosphate broadcast on the surface 20 yr previously provide a marker of cumulative mixing; almost one-half of the residual P had been mixed into the 5- to 15-cm depth by crayfish activity.
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