Nitrogen effects on soil water extraction by tall fescue in northern Appalachia

ABSTRACT:

In the Appalachian region of the northeastern United States, droughty conditions in hill-land soils can cause moisture stress in and reduce yields of pasture grasses. In general, nitrogen (N) fertilization can improve yields and water use efficiency of forage grasses on these types of soils. However, the specific soil conditions under which N fertilization can significantly improve soil water use is not known. The effect of N fertilization of tall fescue (Festuca arundinacea Schreb.) on the water extraction from shale soils commonly found in hill-land pastures in the Northeast was investigated. Tall fescue was grown on three shale-derived soils with total available water-holding capacities of 25.3, 14.4, and 4.9 cm. Nitrogen was applied at the rate of 90, and 180 kg/ha of N in a split application (50% in the spring and 50% after the first harvest). Nitrogen fertilization increased soil water extraction by tall fescue only at soil water storage capacities of 250 mm or more of available water. On soils with less than 250 mm of available water storage capacity, tall fescue was able to exploit the soil water reserves with native amounts of N, but above-ground biomass and water use efficiency was improved with N fertilization.