Recent work has shown that acetylene is a potent inhibitor of nitrification in
soil. To discover the substituted acetylenes which inhibit nitrification in soil,
determination of the effects of seventeen acetylenes monosubstituted (HC" CR)
such as (propyne, 1-butyne, 2-ethynyl- pyridine, phenylacetylene, 3-butyn-2-one, 1-
phenyl-z- propyn -1- 01, 1-pentyne, 4-phenyl -1- butyne, 5-phenyl-1- pentyne, 1-
ethynylcycloh-examine, 2-propyn-1-01, 2·propyn ·1- amine, 1-hexyne, 3-butyn -1- 01,
1-heptyne, 1-octyne, acetylene monocarboxylic acid) and seven disubstituted (RC E
CR) acetylene (2-butyne. 3-phenyl-2·propyn ·1-01, diphenylacetylene, 2-butyn ·1·
01, 2-butyn -1, 4-diol, acetylene dicarboxylic acid, 2-butynoic acid) on production of
(NO ~ + NO ~ )-N in soils treated with (NH.)2 SO •. The obtained data showed that
most of the tested acetylenes substitutes inhibited nitrification process in soil and that
some of them were potent inhibitors of nitrification. The results with the four tested
gaseous compounds showed that acetylene, propyne, and 1-butyne inhibited
nitrification in soils at partial pressures is low (0.1 or 1.0 Pal whereas 2-butyne had
little or no effect on nitrification at partial pressures as high as 10 Pa . Also the
obtained data with the 21 nongaseous compounds showed that 2-ethynylpyridine,
phenylacetylene, and 3-butyn -2- one had the greatest inhibitory effect on nitrification
and that acetylene monocarboxylic acid, acetylene dicarboxylic acid, and 2-butynoiC
acid had the least effect. Studies on the measuring of C2H2 production in soils
treated with the nongaseous compounds showed that the inhibition of nitrification was
not due to C2H2 formed by decomposition of these compounds in the soil.
Experiments indicate that 2-ethynylpyridine and phenylacetylene can be compared
favorably with nitrapyrin (N-Serve) and etridiazole (Dwell) as SOil nitrification inhibitors
and have potential practical value for retarding nitrification of N- fertilizers in soil.