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The presence of ortstein has been implicated in decreased blueberry growth. This study was conducted to determine the effect of podzolizing species, such as blueberry (Vaccinium corymbosum L.) and white pine (Pinus strobus), and depodzolizing species, such as bracken fern (Pteridium aquilinum), bent grass (Agrostis), and fescue (Festuca), on the recementation of crushed ortstein. Crushed ortstein from Saugatuck sand (Typic Durorthod, sandy, mixed, mesic) was passed through a 2-mm sieve and used in column experiments to assess recementation. Aqueous leaf extracts were added to crushed ortstein columns daily for 12 weeks. The degree of aggregation was assessed by determining the amount of recemented (aggregated) ortstein remaining on a 2-mm sieve. Tensile strength of the aggregates was measured to assess aggregate strength. Podzolizer leaf extracts, especially blueberry, were more acidic and produced greater aggregation below 3 cm; however, their strength was no greater than aggregated materials produced by depodzolizing leaf extracts. Aggregated and nonaggregated (loose) materials had similar pH, organic matter and A1 contents. Ortstein pieces treated with leaf extract from depodzolizing species tended to have decreased weight and/or strength. Passing leaf extract through Ap horizon material did not alter its effect on recementation significantly. Blueberry seems to be a strong podzolizer. Bracken fern, a pest species, is an effective depodzolizer, reducing the size of ortstein pieces. Fescue and bent grass are less effective, although they may help offset ortstein recementation associated with blueberries. |
