More water does not necessarily produce more alfalfa seed. A five-year trial near Keith, South Australia, found that strategically delaying irrigation until plants showed early signs of leaf drop generally increased seed yield and consistently delivered the highest gross margin.
The results provide growers with local evidence that controlled moisture stress can improve seed production while reducing irrigation costs. They also show that variety choice remains important, with several varieties performing consistently well across different irrigation strategies and seasons.
Testing varieties under commercial conditions
Established at Warrawee Park near Keith in June 2018, the trial compared 31 proprietary and benchmark alfalfa varieties over five seed harvests, reflecting the productive life of a commercial stand.
Each variety was grown under three flood irrigation strategies. Standard irrigation followed current practice. Under moderate stress, irrigation was delayed until plants began to wilt. Under high stress, watering was delayed until plants showed early signs of leaf drop. Soil moisture and weather data supported irrigation scheduling.
