Productivity of Wet Soils: Biomass of Cultivated and Natural Vegetation

Abstract

Wet soils, soils which have agronomic limitations because of excess water, comprise 105 million acres of non-federal land in the conterminous United States. Wet soils which support hydrophytic plants are "wetlands", and are some of the most productive natural ecosystems in the world. When both above- and belowground productivity are considered, cattail (Typha latifolia) is the most productive temperate wetland species (26.4 Mg/ha/year). Both cattail and reed (Phragmites australis) have aboveground productivities of about 13 Mg/ha/year. Although average aboveground yields of reed canarygrass (Phalaris arundinacea) are lower (9.5 Mg/ha/year), techniques for its establishment and cultivation are we 11-deve1 oped. Other herbaceous wetland species which show promise as biomass crops include sedge (Carex spp.), river bulrush (Scirpus fluviatilis) and prairie cordgrass (Spart ina pectinata). About 40% of wet soils in the conterminous U.S. are currently cultivated, and they produce one-quarter of the major U.S. crops. Most of this land is artificially drained for crops such as corn, soybeans, and vegetables. U.S. wetlands are drained for agriculture at the rate of 223,000 ha/yr. Paddies flooded with water are used to grow rice, cranberries, and wild rice. Forage and live sphagnum moss IV are products of undrained wetlands. A number of federal and state regulations apply to the draining or irrigation of wetlands, but most do not seriously restrict their use for agriculture.