The performance of three Australian wheat varieties at high levels of nitrogen supply

The response of Gabo, Javelin 48, and Bencubbin 48 to nitrogen fertilizers has been compared and changes in soil water and mineral nitrogen contents during the growing season described. Field experiments were conducted on a red brown earth at low and moderate fertility levels in wet and in dry seasons. Nitrogen fertilizer increased tillering early in the season, the greatest increase being shown by Bencubbin. In three of four experiments application of nitrogen led to earlier depletion of soil water, and high rates (60 lb an acre, 120 lb an acre of nitrogen) reduced the grain yield. Gabo was less affected than the other two varieties. On low fertility sites each fertilizer increment produced a considerable increase in grain nitrogen percentage.