Da. Martens et Jm. Bremner, INHIBITORY EFFECTS OF FUNGICIDES ON HYDROLYSIS OF UREA AND NITRIFICATION OF UREA NITROGEN IN SOIL, Pesticide science, 49(4), 1997, pp. 344-352
The influence of 1 and 50 mg active ingredient (Al) kg(-1) soil of 17
fungicides on transformations of urea nitrogen in soil was studied by
determining the amounts of urea hydrolysed and the amounts of nitrate
and nitrite produced when samples of two coarse-textured and two fine-
textured soils were incubated aerobically for various times after trea
tment with urea When applied at the rate of 1 mg AI kg(-1) soil, anila
zine, benomyl, captan, chloranil, mancozeb and thiram retarded urea hy
drolysis in the two coarse-textured soils and maneb retarded urea hydr
olysis in all four of the soils used. Most of the fungicides tested re
tarded nitrification of urea nitrogen in the two coarse-textured soils
when applied at the rare of 1 mg Al kg(-1) soil, but only etridiazole
markedly retarded nitrification of urea nitrogen in all of the soils
used when applied at this rate. When the fungicides were applied at th
e rate of 50 mg AI kg(-1) soil, anilazine, captan, chloranil, fenamino
sulf, folpet, maneb, mancozeb and thiram retarded urea hydrolysis in t
he four soils studied, and all fungicides tested except chloroneb, fen
arimol and iprodione retarded nitrification of urea nitrogen in these
soils. One-way analysis of variance and correlation analyses indicated
that the inhibitory effects of the 17 fungicides tested on nitrificat
ion of urea nitrogen in soil increased with decrease in the organic-ma
tter content and increase in the sand content of the soil.