Transport processes and transformations of urea-N in the unsaturated zone of a heterogeneous, mineral sub-soil

agua del suelo azote circulation de l'eau cultivated land eau du sol eau souterraine flow rate gasto groundwater isotope isotopes metano methane mineral soils nitrification nitrogen noruega norway oxidation oxydation procesos de transporte en el suelo rhizosphere rizosfera soil transport processes soil water suelo mineral tierras cultivadas transport dans le sol urea ureasa urease uree water circulation