EASTERN GAMAGRASS (TRIPSACUM DACTYLOIDES) ROOT PENETRATION INTO AND CHEMICAL-PROPERTIES OF CLAYPAN SOILS

Claypans restrict rooting depth and availability of moisture and nutri ents to plants during periods of drought. Eastern gamagrass (Tripsacum dactyloides var. dactyloides [L.] L.) often remains green during summ er droughts, while other plants turn brown. Questions arose whether ea stern gamagrass roots had or could penetrate claypans to obtain needed moisture. Pits were dug (2 m deep) under eastern gamagrass plants tha t had been growing 50+ and 5+ years at two sites in Missouri. Clay con tents were 30 to 50% in soil layers below 30 cm, and moisture was not limiting in these deep soil layers. Soil pH(Ca) in the lower soil laye rs, except at 180 cm, was below 5.0, and in some cases near 4.0. Extra ctable Al was especially high in the 90 and 120 cm deep soil layers wh ere pH was low. Extractable Ca, Mg, and K increased with soil depth. T he eastern gamagrass roots effectively penetrated claypan soils. Root lengths and root weights were extensive to 180 cm depth, and decreased from the surface with soil depth. Roots of eastern gamagrass were aer enchymous (having cellular compartments which allow air movement) at a ll depths, were mycorrhizal to-at least 150 cm depth, and had relative ly high tolerance to acidic Al toxic Tatum subsoil (Typic Hapludult) a nd toxic levels of Al in nutrient solution. The eastern gamagrass root s also provided root channels through claypans, which could enable new eastern gamagrass or other plant roots to grow into deeper soil layer s.