Corn Root Development in Constructed Soils on Surface-mined Land in Western Illinois
1982
Fehrenbacher, D. J. | Jansen, I. J. | Fehrenbacher, J. B.
The effect of B horizon replacement on corn root development in the reclamation of surface-mined land was studied in a highly productive soil area of western Illinois. Two constructed soils, one with 55 cm of A horizon over 77 cm of replaced B horizon, and the other with 55 cm of A horizon replaced directly over graded dragline spoil, and a third, representative, undisturbed soil, Clarksdale silt loam, were studied. Placement of B horizon material was done without allowing any scraper traffic on the plots, a more careful procedure than would be possible over the entire post-mine surface under current technology. Corn roots were sampled in 1979 directly under one plant using a 10- by 30- by 183-cm soil root monolith. Corn was the first crop planted on the constructed soils following reclamation. The A horizons were similar on all soils. In the replaced B many soil peds were intact and the bulk density was 1.5 g/cm³ throughout, similar to the undisturbed B of Clarksdale. The bulk density of the graded spoil was 1.7 g/cm³ at 54 cm and increased to 1.9 g/cm³ at 102 cm. Depth of root penetration was 163 cm in Clarksdale, 120 cm in A/B, and 74 cm in A/spoil. Root length densities were significantly greater in replaced B than in graded spoil. Below 113 cm, root length densities were significantly greater in Clarksdale than in replaced B. The data suggest that Clarksdale B horizon material, when placed with minimal compaction, is a more favorable rooting medium than the newly placed dragline spoil. Corn yields in 1979, the first year after reclamation, did not substantiate this. However, in 1980 corn yields were significantly higher (1,800 kg/ha higher) on A/B than on A/spoil. Corn yields on undisturbed Clarksdale were about 10% greater than on A over B in 1980.
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