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Title: LAND APPLICATION OF LAKE-DREDGED MATERIALS FOR BAHIAGRASS ESTABLISHMENT IN THE SUBTROPICAL BEEF PASTURE

Author
item Sigua, Gilbert
item HOLTKAMP, MIKE - SW FL WATER MGMT. DIS
item LINTON, JOHN - SW FL WATER MGMT. DIS.
item Coleman, Samuel

Submitted to: Journal of Soils and Sediments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2003
Publication Date: 5/1/2003
Citation: Sigua, G.C., Holtkamp, M.L., Linton, J.M., Coleman, S.W. 2003. Land application of lake-dredged materials for bahiagrass establishment in the subtropical beef pasture. Journal of Soils and Sediments. 3(2):93-99.

Interpretive Summary: Dredged materials are often viewed by society and regulators as pollutants, but many have used these materials in coastal nourishment, land or wetland creation, construction materials, and for soil improvement as a soil amendment. Productive disposal options of lake-dredged materials may provide tangible and intangible benefits that enhance the environment, community, and society. The goal of this study was to explore the use of the Lake Panasoffkee dredged sediments to improve the physico-chemical properties of existing sandy soils in subtropical beef cattle pastures with calcium carbonate- and organic-enriched dredged materials. We applied the lake-dredged materials (LDM) as a soil amendment to establish bahiagrass in a subtropical beef cattle pasture in Sumter County, Florida. Bahiagrass, a warm season perennial, is largely grown throughout Florida, the Coastal Plain, and the Gulf Coast regions of the southern United States. Results disclosed significantly taller and higher biomass production of bahiagrass from plots amended with 75% LDM than those of bahiagrass planted on plots with 0% LDM. Results of this study have demonstrated the favorable and beneficial effects of LDM on establishment of bahiagrass. Sediments with high calcium carbonate from Lake Panasoffkee proved to improve physical and chemical conditions of marginal sandy soils in most subtropical pasture fields, suggesting that LDM could be removed from the spoil containment areas, trucked to other locations, and incorporated into existing fields for agricultural uses. The ability to reuse dredge materials from Lake Panasoffkee for agricultural purposes is important because it reduces offshore disposal and provides an alternative to disposal of the materials in landfills that are already overtaxed. The bottom sediments that were dredged from Lake Panasoffkee contained materials that would neither classify them as a human health risk nor would require expensive hazardous waste handling and disposal. The heavy and trace metal contents of these materials were below the health risk indicators (probable effect levels, PEL and threshold effect levels, TEL). As such, the agricultural or livestock industry could utilize these LDM to produce forages. LDM should be regarded as a beneficial resource, as a part of the ecological system. This study has been continued for several years to explore and assess the long term efficacy of LDM on productivity and quality of bahiagrass beyond its early establishment stage.

Technical Abstract: The continued need to dredge lakes, rivers, and canals in Florida, both for maintenance and environmental improvement, will produce millions of cubic meters of dredged materials. Productive disposal options of lake-dredged materials (LDM) may provide substantial and intangible benefits that will enhance the environment, community, and society. The objective of this study was to assess lake-dredged materials as soil amendment for early establishment of bahiagrass (BG, Paspalum notatum Flügge) in subtropical beef cattle pasture at Sumter County, Florida. This study encompassed two phases: Phase 1 comprised of five small observation plots (0.3 x 0.3 m); Phase 2 consisted of five larger test plots (30.5 x 30.5 m). Each of the plots in Phase 1 and Phase 2 had a different ratio LDM to natural soil (NS): Plot 1 (0% LDM + 100% NS); Plot 2 (25% LDM + 75% NS); Plot 3 (50% LDM + 50% NS); Plot 4 (75% LDM + 25% NS); and Plot 5 (100% LDM + 0% NS). Each plot was seeded with BG and early growth and yield establishment were monitored for 16 weeks. Results disclosed significantly taller (p = 0.001) and higher biomass production (p = 0.001) of BG from plots amended with higher LDM than those of BG planted on plots with 0% LDM. Results suggest that LDM can serve as source of lime and fertilizer to establish BG beef pasture fields. Sediments with high CaCO3 from Lake Panasoffkee (LP) improved the physical and chemical conditions of subtropical beef pastures. Lake-dredged materials could be removed from the spoil containment areas, trucked to other locations, and incorporated into existing fields for agricultural uses. There is still much to be learned, but it is certain that LP sediments should be regarded as a resource, with no observed harmful ecological effects.