CONTROLLED-RELEASE NITROGEN FERTILIZERS AND THEIR AVAILABILITY TO PLANTS

Laboratory and greenhouse experiments were carried out to study the availability of controlled release nitrogen fertilizers ( Nitroform, IBDU,Floran d,and SCU ( as compared with two conventional nitrogen fertilizers ( urea and ammonium sulfate.( A study on the efficience of nitrogenous fertilizers using nitrification inhibitor ( AM ( was also evaluated. laboratory experiments were conducted to study the effect of continuous leaching yhrough soil columns on the solubility of controlled-release and conventional nitrogen fertilizers and evaluation of these fertilizers usign the test of activity index (Ai( . Greenhouse experiments were : the first was to study the effect of controlled-release nitrogen fertilizers compared with ures and ammonium sulfate under effects of method of application on the yield, nitrogen content, and components of wheat plants.