Stickstoffausnutzungseffizienz von 15N-markierter Schafsgülle und 15N-markiertem Mineraldünger in biologisch und konventionell bewirtschafteten Anbausystemen

Summary

Nitrogen (N) utilisation by crops has to be improved to minimize losses to the
environment. We investigated N use efficiency of animal manure and mineral fertiliser
and fate of fertiliser N not taken up by crops in a bio-organic (BIOORG) and a
conventional (CONMIN) cropping system of a long-term experiment over three
vegetation periods (wheat-soybean-maize). Microplots received a single application of
15N-labelled slurries or mineral fertiliser. At the end of each vegetation period we
tested whether higher microbial activity and biomass in BIOORG than CONMIN soils
and lower long-term N input level in BIOORG affected use efficiency and fate of
fertiliser N not taken up by crops. In total 41%, 15% and 50% of 15N applied as urine,
faeces and mineral fertiliser was recovered by the three crops. 15N recovered from
originally applied urine, faeces and mineral fertiliser in the topsoil at the end of the
third vegetation period was 19%, 25% and 20%, respectively. Of urine-, faeces- and
mineral fertiliser-15N 40%, 61% and 29% was not recovered by the three crops and in
topsoil suggesting significant transport of 15N-labelled components to deeper soil
layers. BIOORG and CONMIN differed neither in fertiliser N use efficiency by crops
nor in 15N recovery in soil indicating insignificant differences in turnover and utilization
of applied manure N in the bio-organic and conventional cropping system.