Wheat nitrogen indices response to nitrogen source and application time.

The unnecessary inputs costs to farmers due to N losses can be optimized by developing a sound fertilizer strategy. The optimization for improved wheat productivity, N re-translocation, utilization and use efficiencies can be achieved through source and timing of N application. Thus, an experiment was carried out at the Research Farm of KPK Agricultural University Peshawar during 2005-06 to test the effects of sources and timing of N application on wheat biological yield and N indices. Nitrogen sources were ammonium (NH4-N) and nitrate (NO3-N) applied @ 100 kg ha -1 at three different stages i.e., at sowing (S1), tillering (S2) and boot stage (S3). Ammonium-N increased wheat biological yield and total N uptake whereas nitrogen utilization efficiency was increased with NO3-N. Split N at sowing, tillering and boot stages had increased the biological yield and apparent N re-translocation, whereas total-N uptake and N harvest index was higher for full application of N at boot stage. Nitrogen application had almost double the N uptake compared to control and increased 27% N retranslocation regardless of sources and application time. It was concluded from the experiment that split application of N had higher wheat productivity and re-translocation, whereas full and delayed N dose increased N harvest index compared to other treatments. Thus, split N application is recommended for improved biological yield, whereas for improved quality of grains the delayed application of N at boot stage is preferable in agro-climatic conditions of Peshawar.