Short-term anaerobic storage of 15N-labelled sheep urine does not influence the mineralization of nitrogen in soil

Abstract

The turnover of 15N-labelled fresh and anaerobically stored urine was studied in two soils of different texture. 15N-labelled urine was obtained by feeding a sheep on 15N-labelled hay. A sandy (4.5% clay) and a sandy loam soil (17% clay) were incubated at 23 °C with 100 /ig N g−1 soil in 15N-labelled sheep urine or in (15NH4)2SO4. After 2 days of incubation, there was no significant effect of urine storage on the net mineralization of N. After 55 days of incubation, the total recovery of labelled urine-N was 96% in the sandy soil and 92% in the sandy loam soil. In the same soils 85% and 67% of the labelled urine-N was recovered as inorganic N, respectively. The net mineralization of urine-N was lower in the sandy loam than in the sandy soil because there was a larger increase of the biomass N concentration in the sandy loam soil after urine application.