Effect of humic acid foliar spraying and nitrogen fertilizers management on wheat yield

Foliar feeding has been used as a mean of supplying supplement doses of minor and major nutrients, plant hormone, stimulants and other beneficial substances. It is reported that foliar application of humic acid enhances the nitrogen use efficiency by crops because it is effective at ameliorating the leaf intevenal chlorosis that occurred during early growth of wheat seedlings and hence improves yield. To test this hypothesis an experiment was planned to see the effect of foliar application of humic acid on nitrogen use efficiency on grain and straw yield of wheat in split plot design with three replications at Soil Chemistrty Section, Ayub Agricultural Research Institute, Faisalabad during 2012-13. Experiment included two levels of foliar humic acid spray (H1: 0 and H2: 40 mg/L) in main plot and five levels of nitrogen fertilizer (N1: 0, N2: 60 kg/ha, N3: 90 kg/ha, N4: 120 kg/ha, N5: 150 kg/ha nitrogen from urea) in subplots. Foliar spray of humic acid was done at two stages i.e. at tillering and at booting stage. At maturity, grain and straw yield was recorded. Interaction effect of foliar humic acid spraying and nitrogen fertilizer management on grain yield and straw yield showed statistically significant results at 5% probability level. The highest grain yield (5.02 t/ha) was obtained from use of 40 mg/L HA+ 150 kg N/ha nitrogen fertilizer. Whereas N4H2 and N5H1 gave statistically similar yield i.e. 4.58 t/ha. Nitrogen use efficiency was also improved in all treatments where 40 mg/L humic acid foliar spray was used along with nitrogen