N-heterocyclic compounds used as nitrification inhibitor

A method for inhibiting nitrification, comprising utilizing an N-heterocyclic compound of the general formula (a) or (b)

• with the following definitions:
• X1 being S or O, X2 being S or O and at least one of X1 and X2 being S
• R2 H or C1-4-alkyl,
• R3 H or C1-4-alkyl
• R6 and R7 are hydrogen or together form a covalent carbon-carbon bond
• in general formula (a) R1 being H, C1-12-alkyl or —CH2—NR4R5 with
• R4 hydrogen or C1-4-alkyl,
• R5 C1-12-hydrocarbon residue which can contain one to three halogen atoms and/or one to four heteroatoms, selected from the group consisting of nitrogen, oxygen and sulfur, it also being possible for R4 and R5, together with the nitrogen atom joining them, to form a 5- or 6-membered saturated or unsaturated heterocyclic radical, which optionally may also contain one or two further heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur,
• in general formula (b) R1 being H or C1-17-hydrocarbon, preferably H, or —CH2—R5 with R5 being H or C1-16-hydrocarbon residue, which hydrocarbon can contain one to three halogen atoms and/or one to six heteroatoms, selected from the group consisting of nitrogen, oxygen and sulfur,
• and preferably in general formula (a) and (b) X1 and X2 being S,
• as nitrification inhibitor,
• wherein the N-heterocyclic compound of the general formula (a) or (b) is an N-heterocyclic compound of the general formula (I) or (II) or (III) or (IV)
• with the following definitions:
• X1 being S or O, X2 being S or O and at least one of X1 and X2 being S
• R2 H or C1-4-alkyl,
• R3 H or C1-4-alkyl
• in general formula (I) and (III) R1 being H, C1-12-alkyl or —CH2—NR4R5 with
• R4 hydrogen or C1-4-alkyl,
• R5 C1-12-hydrocarbon residue which can contain one to three halogen atoms and/or one to four heteroatoms, selected from the group consisting of nitrogen, oxygen and sulfur, it also being possible for R4 and R5, together with the nitrogen atom joining them, to form a 5- or 6-membered saturated or unsaturated heterocyclic radical, which optionally may also contain one or two further heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur,
• in general formula (II) and (IV) R1 being H or C1-17-hydrocarbon, preferably H, or —CH2—R5 with R5 being H or C1-16-hydrocarbon residue, which hydrocarbon can contain one to three halogen atoms and/or one to six heteroatoms, selected from the group consisting of nitrogen, oxygen and sulfur,
• and preferably in general formula (I), (II), (III) and (IV) X1 and X2 being S.