Cocksfoot pasture production in relation to environmental variables

Abstract

The effects of temperature, water and nitrogen on pasture production of an 8 year old 'Wana' cocksfoot pasture were quantified at Lincoln University, Canterbury. The maximum dry matter (DM) yield was 22.0 t/ha/yr when neither water nor N were limiting. Crude protein yield of +N pastures was 3.2-4.2 t/ha/yr compared with 1.0 t/ha in -N pastures. Metabolisable energy averaged 178*103 MJ ME/ha/yr for the +N pastures compared with 69*103 MJ ME/ha/yr for -N pastures. Seasonal differences in pasture production were explained in relation to thermal time with 7.0 kg DM/oCd for N fertilised pastures and 3.3 kg DM/oCd when no N was applied. During periods of water stress, relative yield decreased at a rate of 1.4%/mm when the soils critical limiting deficit of 78 mm was exceeded. Keywords: Dactylis glomerata, irrigation, nitrogen, thermal time.