Yoana Newman, Texas A&M Univ. Soil & Crop Science, 1229 North US Hwy 281, Stephenville, TX 76401, United States of America, James Muir, 1229 North US Hwy 281, Texas Agricultural Experiment Station (Main Office), Texas Agr. Exp. Station, Texas A & M University, Stephenville, TX 76401, Johannes Scholberg, 304 Newell Hall, "PO Box 110500, Univ. of FL.", Gainesville, FL 32611-0500, United States of America, and Martin Adjei, University of Florida, 3401 Experiment Station, Ona, FL 33865-9706, United States of America.
The role of forage plants for accumulating and removing excessive residual soil nutrients is expanding. Traditionally, the sole intent in their production has been the feeding of grazing animals. In environmentally sensitive areas, forages may be used to remove surplus nutrients and thereby remediate impacted soils while feeding value may become a secondary objective. This trend is most prevalent at concentrated animal feeding operations located in the vicinity of environmentally sensitive water bodies. The watershed of the North Bosque River in Texas and Lake Okeechobee in Florida are two examples of this nation wide trend. In both regions, intensive efforts focus on potential use of pasture management to enhance extraction efficiency of excess soil P on a year-round basis. Although nutrient removal is a function of target-nutrient concentration and plant yield, the importance of the latter often overrides the first. As such, the main candidates for phytoremediation in these southern states include perennial warm-season plants such as bermudagrasses (Cynodon dactylon; common, Tifton 85), bahiagrass (Paspalum notatum), limpograss (Hemarthria altissima), Brachiarias (Brachiaria spp) and others that have high production capacities. Management practices include, among others, greenchop or harvest at early stages (18-21 d), silage or hay production, increased use of inorganic fertilizer to enhance the ability of the plants to extract additional P, and the use of complementary cool-season forages to achieve maximum year round extraction.