| abstract |
Disclosed is the use as nitrification inhibitors of pyrazole derivatives of formula (I), or salts thereof, in which the groups R1-R4 have the following meanings: R?1, R2 and R3¿ represent C¿1?-C20 alkyl, C3-C8 cycloalkyl, C5-C20 aryl or alkyl aryl (these four groups can be singly or doubly substituted by a halogen and/or hydroxyl), and halogen, nitro or hydrogen; and R?4¿ represents either (a) C¿6?-C20 alkyl, one or two hydrogen atoms being optionally substituted by a halogen; or (b) C1-C20 alkyl. In the latter case, 1-4 hydrogen atoms can be substituted by a group of formula (II), in which R?5, R6, and R7¿ represent C¿1?-C20 alkyl, C3-C8 cycloalkyl, C5-C20 aryl or alkyl aryl (these four groups can be singly or doubly substituted by a halogen and/or hydroxyl), as well as halogen, nitro or hydrogen; and 1 or two hydrogen atoms are optionally substituted by a halogen. |