Aspects of grassland management for pasture-based dairy farms with wet soils and fragmented farm area

A long grazing season improves the profitability of pasture-based dairy farms. However, an increasing proportion of Irish milk is produced on farms where achieving a long grazing season is difficult. This study investigated how grassland management on farms with wet soils and fragmented farm area can be adapted to establish systems that maximise farm productivity and profitability. An experiment with four grazing systems evaluated if soil moisture measurements can be an effective decision support to assess the risk of treading damage, impact on pasture productivity and dairy cow performance during wet soil conditions. The effect of grazing platform stocking rate (GPSR) on the productivity and profitability of fragmented pasture-based farms was evaluated in a second experiment with four grazing systems where a higher GPSR was supplemented with silage produced on non-GP parcels of the farm. Finally, it was investigated if accumulating herbage mass during autumn can lengthen the grazing season on pasture-based dairy farms. Less time spent at pasture during wet soil conditions lowered treading damage but had no effect on annual herbage production. Milk solids production and profitability were higher when cows spent more time at pasture despite also incurring higher treading damage. Measuring soil moisture was a useful decision support for assessing the risk of treading damage when turning cows out to pasture. GPSR did not affect herbage production or milk production per cow albeit with a lower proportion of grazed herbage in the diet with higher GPSR. A greater extent of farm fragmentation lowered the profitability of pasture-based dairy production. The profitability of increasing GPSR was mainly determined by external factors. Higher milk prices, shorter distances and lower land rental price increased the optimum GPSR of fragmented systems. Accumulating herbage mass during autumn facilitated a longer grazing season while not impacting on milk production.