A comparison of plant available nutrients on decomposed granite cut slopes and adjacent natural soils
✍ Scribed by V. P. Claassen; R. J. Zasoski
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 162 KB
- Volume
- 9
- Category
- Article
- ISSN
- 1085-3278
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✦ Synopsis
Decomposed granite (DG) slopes are often dicult to revegetate after existing topsoil and vegetative cover have been removed. In this study, naturally vegetated soils and denuded DG cut slopes were evaluated to compare edaphic (soilrelated) conditions that may dier between the vegetated and non-vegetated states. Potential plant nutrient de®ciencies were evaluated by soil nutrient extraction, plant tissue analysis and by greenhouse bioassay methods. The DG cut slopes have approximately one-quarter to one-half the clay content, soil organic matter, water-holding capacity, and total and available nitrogen (N) of the adjacent natural soils. Soil extraction tests for phosphorus (P) availability gave variable results, but a growth response to P amendment was observed in a greenhouse bioassay. The native topsoils and the DG cut slope materials had non-limiting levels of pH, exchangeable Ca, Mg and K, and total P. Cation exchange capacity and sulfate±sulfur (S) were low but similar between the two soil groups. Principle nutrient limitations are interpreted to be N, P, and possibly S and boron (B), in order of decreasing severity. Based on these results, we conclude that the removal of humi®ed soil organic matter on the cut slopes reduces plant growth directly by lowering several of these essential nutrients, and indirectly by decreasing the soil's water-retention and in®ltration capacity. Soil organic matter is viewed as a critical factor and major contrast between barren and revegetated DG materials.