1. The impact of late applications of N-fertilizer on the grain protein of wheat in the Mediterranean climatic region of Western Australia Jairo A Palta Bill Bowden Senthold Asseng Supported by

2. Introduction 1. The AWB has recently introduced payments for wheat grain protein in order to improve its marketability

3. Grain protein prices for Western Australia wheat in 2000-2001

4. Introduction 2. These payments have made decisions on the application of fertilizer N to wheat more critical for profits.

5. N applications, early growth and grain protein content 3. Grain protein can be increased by pre-tillering applications of fertilizer-N through an improved early vegetative growth.

6. Pre-tillering N applications and grain protein content N applied (Kg/ha) N at maturity (g m -2 ) Grain N yield (g m -2 ) NHI Grain protein (%) Grain yield (t/ha) 155.2 3.5 0.68 10.2 1.94 15/15 6.74.50.6711.42.26 30/30 8.65.40.6313.12.35 l.s.d. (P=0.05) 1.32 0.710.030.790.32

7. Leaching of N 4. Water loss by deep drainage can occur in early winter when vegetative growth and N uptake is slow. Low recoveries of N-fertlizer Leaching of N

8. Leaching of N and rainfall distribution 5. Leaching of N is mainly a consequence of the distribution of rainfall. 70% of the annual rainfall is received between May-July.

9. Mediterranean-type environment Western Australian wheat-belt ET pot sowing grain fill

10. Information on management of grain protein 6. Growers are seeking information that delay decisions and expenditure on N fertilizer until late in the season when weather, yield potential and grain prices are clearer. Aim Evaluate the efficacy of post-tillering applications of N-fertilizer in increasing the grain protein content in wheat.

11. Post-tillering N applications and grain protein content Wongan Hills in the central wheatbelt of WA. 390 mm annual rainfall Deep yellow earthy sand (USDA Typic Xeric Psamment).

12. Post-tillering N applications and grain protein content Seeding N (kg/ha ) Post-tillering 15 N-fertilizer SE(DC25 ) B (DC42 ) A (DC61) 0 30kg/ha 50 30kg/ha

17. Conclusions Post-tillering applications of N-fertilizer to wheat can increase grain yield and protein content in seasons when: 1. There are not losses of water and N from deep drainage. 2. Late rains are capable to keep the soil surface moist for long enough to allow the fertilizer-N to be taken up by the crop.