Modelling the effects of stocking rate, soil type, agroclimate location and nitrogen input on the grass DM yield and forage self-sufficiency of Irish grass-based dairy production systems

Abstract In pasture-based dairy production systems, identifying the appropriate stocking rate (SR; cows/ha) based on farm grass growth is a key strategic decision for driving overall business. This paper investigates number of scenarios examining effects SR (2–3 cows/ha (0.25 unit changes)), annual nitrogen (N) fertilizer application rates (0–300 kg N/ha (50 kg/ha soil type (heavy and free-draining soil) agroclimate location ((south northeast Ireland) across 16 years) pasture forage self-sufficiency using herd dynamic milk model merged with Moorepark St Gilles model. The modelled outputs were growth, dry matter intake, silage harvested offered, N surplus. calculated that yield increased from 9436 DM/ha/year when 0 N/ha/year was applied to 14 996 300 applied, an average response 18.4 DM/kg (range 9.9–27.7 applied). Systems stocked at 2.5 applying 250–300 fertilizer/ha/year self-sufficient forage. As input reduced 250 N/ha/year, declined, as did results showed reduction in 50 kg/ha/year will require 0.18 maintain ( R 2 = 0.90).