Hardwood Fertilization: Research Progress in the Midsouth

To meet the increasing demand for wood and wood products, the Southern Hardwoods Laboratory is investigating silvicultural techniques such as fertilization. Sweetgum, water oak, and willow oak have responded to N and NPK on clay soils of the Mississippi River floodplain. Yellow-poplar growth has been improved by NPK fertilizers on eroded sites in the Silty Uplands, and in the greenhouse sycamore on Coastal Plain alluvial soil has responded to additions of P. Largest fertilizer responses have been by cottonwood plantations on medium-textured old-field soils in the Mississippi River floodplain. Nitrogen has produced 200% increases in volume growth on these sites. The gain from fertilization appears to be greatest in stands older than 2 or 3 years. Additional