Wednesday, November 15, 2006

Agricultural Efficacy of Carbonatic Lake-Dredged Materials in Enhancing Pasture Establishment.

Gilbert Sigua, USDA-ARS, Subtropical Agricultural Research Station, 22271 Chinsegut Hill Rd., Brooksville, FL 34601, Samuel Coleman, USDA-ARS-STARS, 22271 Chinsegut Hill Road, Brooksville, FL 34601, and Joseph Albano, USDA-ARS Horticultural Research Laboratory, 2002 S. Rock Road, Ft. Pierce, FL 34945.

Disposal and environmental quality of dredged sediments from navigational channels, lakes and rivers have been judged as beneficial by combinations of physical, chemical, and biological analyses for over 30 years. However, many people in the scientific community find this approach objectionable since the data does not provide sufficient environmental protection information because several site-specific geochemical and biological factors are typically excluded from the decision-making process. A four-year (2001-2005) study was conducted on land application of carbonatic lake-dredged materials as an option for disposal on a beef cattle pasture in south central Florida. Addition of carbonatic lake-dredged materials (CLDM) had significant (p ≤ 0.001) effects on soil quality and favorable influence on forage establishment and nutritive values. Compared with the control plots (0 g kg-1 CLDM), the soils in plots amended with CLDM exhibited: (1) lower penetration resistance; (2) an increase in soil pH and exchangeable cations (Ca and Mg); and (3) decrease in the levels of soil trace metals. Results disclosed consistently and significantly (p ≤ 0.001) higher bahiagrass (BG) biomass (-106.3x2 + 1015.8x – 39.2; R2=0.99**) and crude protein content (1.24x + 6.48; R2 = 0.94**) from plots amended with CLDM than those of BG planted on plots with no CLDM treatment. Land application of CLDM may provide substantial benefits that will enhance the environment, community, and society. The ability to reuse these materials 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.