- - - Environment and Natural Resources, Norwegian Institute of Bioeconomy Research, Ås, Norway
- - - Environment and Natural Resources, Norwegian Institute of Bioeconomy Research, Ås, Norway
- - - Environment and Natural Resources, Norwegian Institute of Bioeconomy Research, Ås, Norway
- - - University of Debrecen, Research Institute of Nyíregyháza, Nyíregyháza, Hungary

Purpose Sorption could be a way to concentrate nutrients in diluted waste streams to bring more nutrients back to agriculture. The aim of this work was to model the fate of sorbed NH۴+ content in liquid waste streams by adding nitrogen (N) sorbed to a sorbent, zeolite, and study its effect on early growth and potential leaching losses. Methods A pot experiment with two soil types and wheat as test crop was conducted. Mineral N in soil was measured, and a leaching experiment performed. ۱۵N labelled ammonium was sorbed to zeolite. The fertilizer effect was then compared to ammonium fertilizer applied the conventional way, with and without zeolite. Results Early uptake of sorbed ammonium was reduced by ۵۶% compared to ammonium applied conventionally, and soil uptake compensated only very early. Nitrate concentration in leachates was reduced by ۱۲% in sandy soil when N was applied sorbed to zeolite. However, leaching of water through the profile increased ۷۱% when N was applied sorbed to zeolite, so that there was only a tendency to lower N losses when N was applied sorbed to zeolite. Conclusion Ammonium-N sorbed to zeolite is less plant available than conventionally applied N but may also be less prone to leaching losses.

Sorption, zeolite, Nitrogen leaching, Root:Shoot ratio