Comparison of a pasture-based system of milk production on a high rainfall, heavy-clay soil with that on a lower rainfall, free-draining soil

The objective of this study was to compare the biological and economic efficiency of a seasonal pasture‐based spring calving system of milk production on a high‐rainfall, heavy‐clay soil Kilmaley (KMY)] to that on a lower‐rainfall free‐draining soil Moorepark (MPN)] in Ireland. The physical performance data were obtained from a 3‐year study (1998–2000) carried out at both sites. Analysis of the system of milk production at the two sites was undertaken using the Moorepark Dairy System Model. Herbage dry‐matter production was greater at the MPN site with a greater proportion being produced between 1 September and 1 May. On average, over the 3 years, the system of milk production at the MPN site had a higher stocking rate (2·34 vs. 1·89 cows ha^?1), higher milk production per cow (6421 vs. 5781 kg per cow), longer grazing season (250 vs. 149 d) and a higher proportion of the diet of the herd from grazed grass (0·70 vs. 0·40) than at KMY. Economic analysis showed that, in a 468 100 kg European Union milk quota scenario, the profitability at the MPN site was €28 417 greater than at the KMY site. At similar milk production per cow it was €19 138 greater. Monte Carlo simulation showed that the MPN site was stochastically dominant over the KMY site. Sensitivity analyses showed that farm profit was most sensitive to changes in milk price. The results also indicated that milk production in the future may not be sustainable economically on high‐rainfall, heavy‐clay soils in Ireland.