Some furfural derivatives as nitrification inhibitors

Three series of furfural derivatives, namely N-O-furfural oxime ethers, fur fural Schiff bases (furfurylidene anilines), and furfural chalcones, have b een synthesized and evaluated for nitrification inhibition activity in labo ratory incubation studies in typic Ustocrept soil. Furfural oxime ethers an d furfural Schiff bases showed potential activity, but furfural chalcones w ere only mildly active. N-O-ethyl furfural oxime among the oxime ethers, an d furfurylidine-4-chloroaniline among the furfural Schiff bases, performed the best. These two compounds showed more than 50% nitrification inhibition on the 45th day at 5% dose as compared to 73% inhibition by nitrapyrin. Ac tivity of furfural oxime ethers decreased with an increase in carbon atoms in the N-O-alkyl side chain. Introduction of a chlorine atom in the phenyl ring of furfurylidene anilines increased the persistence of their activity. N-O-Ethyl furfural oxime and furfurylidine-4-chloroaniline coated urea per formed at par with their application in solution form. Ethyl and N-O-isopro pyl oxime, as well as chloro- and nitrosubstituted Schiff bases, did not re veal any phytotoxicity (adverse effect on germination) on chickpea seeds (C icer arietinum) even at the highest dose (40 ppm, soil basis).