Implications for N Transformations in Acidic Soils of Replacing Annual-Based Legume Pastures with Lucerne-Based Pasture in Dryland Farming Systems of Southern Australia

Implications for N Transformations in Acidic Soils of Replacing Annual-Based Legume Pastures with Lucerne-Based Pasture in Dryland Farming Systems of Southern Australia

The supply and demand for nitrogen (N) in annual-based pasture-crop rotations in southern Australia is often poorly synchronised, leading to large losses of inorganic N (Fillery, 2001). Perennial pasture species, particularly lucerne, are being recommended to minimise dryland salinity. The implications for N cycling of using lucerne in place of annual legumes on acidic sandy soils that are widespread have not been widely studied. Lucerne is less tolerant of acidity and could fix less N than annual legumes. Lucerne root residues mineralise at slower rates than annual pasture residues with lower N release to subsequent wheat crops (Bolger et al., 2003). The aims of the work were to compare N cycling under lucerne and the traditional annual legume-based pasture system.