Influence of different forage grasses on nitrate capture and leaching loss from a pumice soil

Nitrogen (N) uptake and loss in leachate from a pulse of 15N-labelled synthetic cow urine applied to a pumice soil were compared in a glasshouse lysimeter experiment among the grass species, Agrostis capillaris, Dactylis glomerata, Phalaris aquatica, Lolium multiflorum, L. perenne and a L. multiflorum/A. capillaris mixture. In addition, four L. perenne treatments investigated the effect of infection by Neotyphodium lolii strains. Leachate volumes and leachate nitrate concentrations were measured. At final harvest 24 weeks after sowing, dry matter (DM) mass of shoots and roots, plant N and 15N contents, soil residual mineral N, and root diameters and lengths were measured. Endophyte had no effect on plant or nitrate variables. Lysimeters planted with L. perenne (pooled endophyte treatments) leached 48 mg of NO(3)-N compared with < 3 mg N for the other grasses. Recovery of 15N was highest in A. capillaris (0 center dot 99), followed by D. glomerata and P. aquatica (0 center dot 89), the L. multiflorum/A. capillaris mixture (0 center dot 87), L. multiflorum (0 center dot 60) and L. perenne (0 center dot 44). Low 15N recoveries and high leaching losses from L. perenne were associated with low plant and root masses of DM and low rooting depth. High aerial mass of DM, root systems extending below 20 cm and high root masses of DM in lysimeters with A. capillaris, P. aquatica and D. glomerata contributed to a high rate of nitrate interception by these species and low leachate losses. The L. multiflorum/A. capillaris mixture was intermediate between the two species for most of the variables measured.