Evaluation of the water use efficiency of dairy production using crops and pastures

Abstract

This study evaluated the water use efficiency (WUE) of milk and forage production from a range of temperate and tropical forages on 5 dairy farmlets and a small field plot study located at Mutdapilly Research Station in south east Queensland. The feedbase had a greater affect on the WUE of milk production than the volume of irrigation and rainfall received. For instance, the high irrigation, high quality temperate pasture based (M4) farmlet received an additional 36% volume of water when compared to the crop based feedlot (M5) farmlet, though milk production from forage was 30% less. This difference in efficiency occurred in part from the superior WUE of the irrigated maize (Zea mays) summer crop with 3.4 t DM/ML and lucerne (Medicago sativa) winter crop with 2 t DM/ML, and the increased efficiency of herbage utilisation from the conservation of crops compared with grazing of pastures. The raingrown (M1) farmlet’s WUE of milk production was relatively high, however forage production was limited and consequently milk yield was comparatively low. The range in herbage WUE associated with forage species was consistent between the farmlet and small plot studies. Farmers are challenged with striking a balance between selecting forage types that optimise WUE and those that increase diet quality.