Pesticide Research Journal

A series of 1, 4-diazabicyclo-[2, 2, 2]-octane (DABCO) salts has been synthesized and evaluated for nitrification inhibitory activity in a laboratory incubation experiment at 10% of applied urea-N. Most derivatives showed 11.9–38.6 and 3.4–18.7% nitrification inhibition after 10 and 20 days, respectively. 1-Benzyl-4-aza-1-azoniabicyclo-[2, 2, 2]-octane chloride showed 33.8% nitrification inhibition followed by 1 -propyl-4-aza-1 -azonnabicyclo-[2, 2, 2]-octane chloride. On the basis of four parameters viz., concentration of ammonium-N and nitrate-N, % nitrificatton inhibition (NI), ratio of ammonium-N to nitrate-N, and total mineral-N, used as indicators of effectiveness of an inhibitor 1-benzyl-4-aza-1-azoniabicyclo-[2, 2, 2]-octane chloride (9) showed the highest relative efficiency after nitrapyrin throughout the experiment. 1 -Propyll4-aza-1 -azonnabicyclo-[2, 2, 2]-octane bromide (4) showed the second highest relative efficiency followed by 1 -pentyl-4-aza-1 -azonnabicyclo-[2, 2, 2]-octane bromide (8) on the 10^th day. But the ranks were reversed on the 20^th day, the compound 8 having the higher relative efficiency than 4 possibly due to faster degradation of 4.