USE OF NITRIFICATION INHIBTOR (8-HYDROXYQUINOLINE) WITH SOME NITROGEN FERTILIZERS FOR WASHINGTON NAVEL ORANGE PLANTS

Nitrification inhibitor (8-Hydroxyquinoline, 8-HQ) was tested at rates of 0, 25, 50 and 100 mg/l with N-fertilizers (Urea and Ammonium sulfate) on pot grown Washington navel orange.
Plant growth parameters (plant height, stem diameter, growth rate, volume index and plant dry weight) were increased with 8-HQ applications.
The increases were more pronounced at the rate of 50 mg/l and also in the case of urea fertilizer.
Divalentcations, Ca²⁺ and Mg^2- were decreased when 8-HQ was added to N-fertilizer.
The inverse effect was noticed with other elements.
Leaf N increased with 8-HQ inhibitor due to the inhibition effect on nitrification process and thereby reduced N losessed by leaching (as NO_3-) and volatilization (as NH₃) and also more absorption of N in the form of (NH₄₊). Soil-N was higher at the end of both years when 8-HQ was added with N-sources.
The inhibition effect of 8-HQ was more pronounced with are than with ammonium sulfate.
Generally, 8-HQ inhibitor at a rate of 50mg/l with urea fertilizer was more effective in suppressing the nitrification of N-fertilizers and also increased the plant growth parameters.

III International Symposium on Mineral Nutrition of Deciduous Fruit Trees

S.M. El-Shazly

https://doi.org/10.17660/ActaHortic.1997.448.93