Increase of N use efficiency in wheat fertigation method by optimum split N at growth stage.

order to determine optimum of amount and time for applying N fertilizer in wheat field by fertigation this experiment designed. This experiment was T statistical analyzes design consist of 3 amount of N and 3 time of N use(wheat growth stages) as follow A & B paragraphs from 2004 for two years in Karaj research station. A- N amount treatments: N1: 67.5 Kg/ha, N2: 100 Kg/ha, N3: 135 Kg/ha N time use treatments: S1: Tillerring stage(1 time), Stem Elongation(1 time) & Inflorescence emergence(1 time) S2: Tillerring stage(1 time), Stem Elongation(2 times), Inflorescence emergence(1 time) & Anthesis(1 time) S3: Tillerring stage(2 times), Stem Elongation(2 times), Inflorescence emergence(2 times) & Anthesis(1 time) At the end of 1th year yield of wheat on N1 treatment rediuce forthere treatments adjusted. B- N amount treatments: N1: 100 Kg/ha, N2: 117 Kg/ha, N3: 135 Kg/ha N time use treatments: S1: Tillerring stage(1 time), Stem Elongation(1 time) & Inflorescence emergence(1 time) S2: Tillerring stage(1 time), Stem Elongation(2 times), Inflorescence emergence(1 time) & Anthesis(1 time) S3: Tillerring stage(2 times), Stem Elongation(2 times), Inflorescence emergence(2 times) & Anthesis(1 time) Results of 1th year as this research indicated that difference between N1&N2 did not significant. But differences between N1&N3 , N2&N3 were significant. The N time use treatments did not significant. Interaction between N and S showed for N1 or low amount of N, low split N in stages was good. The highest yield was 6.722 ton/ha on N2S2 treatment. Results of 2th year as this research indicated that treatments did not significant. The highest yield was 5.041 ton/ha on N2S1 treatment. In this treatment N application 12.5 percentage reduce in fertigation in compare with general amount of N use. Key words: Fertigation, Water use efficiency and Nitrogen : Abstract