Author
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Morris, Dolen |
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Submitted to: Soil and Crop Science Society of Florida Proceedings
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/11/2005 Publication Date: 8/26/2005 Citation: Morris, D.R. 2005. Dry matter allocation and root morphology of sugarcane, sawgrass, and st. augustinegrass due to water-table depth. Soil and Crop Science Society of Florida Proceedings. 2005. 64:80-86. Interpretive Summary: Soils in the Everglades Agricultural Area of south Florida are subsiding due to decomposition by aerobic microorganisms. Growing plants that can add organic matter back to the soil is a means to restore soil losses. Sawgrass is the native plant that built the organic soils of the Everglades over a 5,000-yr period, but it grows slowly and doesn't compete well with current plants growing in the region. An experiment was conducted to compare dry matter production and root growth of agricultural crops with sawgrass to identify if other crops have the potential for restoring Everglades soils. Sawgrass, sugarcane, and St. Augustinegrass were grown outside in 10 gal containers containing an organic soil. Water-tables were maintained at the soil surface and at 6 inches from the soil surface. After one year, plant dry matter and root yields were compared. Averaged across water-table depths, sugarcane produced 12 and 4 times more above and below ground dry matter, respectively, than sawgrass. St. Augustinegrass produced about the same amount of shoot and root dry matter as sawgrass. Sugarcane also produced 13 times more root length than sawgrass, indicating it had a greater potential for absorbing nutrients. As with dry matter yield, St. Augustinegrass produced similar quantities of root length as sawgrass. Sugarcane appears to have potential for building Everglades peat soil, while reducing nutrient levels in ground water, which could aid in restoration efforts. Technical Abstract: Peat soils in the Everglades Agricultural Area of south Florida are subsiding and releasing nutrients in waterways due to decomposition by aerobic microorganisms. Restoring Everglades peat involves adding organic matter back to the soil as did the native sawgrass in predrainage time and removing nutrients from soil water. It is not certain if sawgrass is more efficient at accumulating dry matter than agricultural crops. This experiment was conducted to compare dry matter yield distributions and root morphology of sugarcane, sawgrass, and St. Augustinegrass growing under different water-table depths. Plants were grown outside in 38-L pots containing a Pahokee muck soil (Euic, hyperthermic Lithic Haplosaprist) under 15- and 30-cm water-tables. All plants were harvested after 11 months. Across water-table treatments, sugarcane produced 55 kg m-2 total dry matter (above plus below ground), while sawgrass and St. Augustinegrass had similar total dry yields averaging 5 kg m-2. Sawgrass allocated 34% of its dry matter below ground averaged across of water-table depths compared with 14 and 8% for sugarcane and St. Augustinegrass, respectively. However, sugarcane had 4 and 20 times more below ground dry matter than sawgrass and St. Augustinegrass, respectively. In addition, sugarcane yielded 308 km m-3 of total root length averaged across water-table treatments compared with an average of 24 km m-3 for sawgrass and St. Augustinegrass, indicating that sugarcane had a much greater capacity for absorbing nutrients from soil water. Sugarcane appears to have potential for building Everglades peat soil, while reducing nutrient loading in ground water, and allowing for coexistence of agriculture in the restoration efforts. |
