Over winter, the area was grazed by dry cows and heifers, with the milkers due back in about October. For most of the summer, the dairy herd was about 180 milkers. Fertiliser program Most phosphorus and potassium fertiliser was applied before irrigation started and most nitrogen was applied over summer. The summer fertiliser program is shown in Table 1. The Summit blend was applied to the drained borders at the end of September but the undrained borders were not dry enough to top dress until the end of November.
Soil test results All borders are soil sampled annually.
5.0 4.8 Phosphorus and potassium levels were very high in May 1999 following heavy fertiliser applications for maize. They have dropped substantially but are still higher than they were at the start of the project. The drained area shows the larger drop, with salinity now being about one third less than on the undrained area. Reduced salinity on the drained area has also shown up on some preliminary EM 38 re-mapping of the area. This ensures that drainage is not too rapid and allows a realistic 'leaching fraction' of irrigation, while keeping the mole and pipe drains working.