Effects of two nitrogen enriched biochars on barley grown on peat : preliminary observations

The ability of biochar to sorb ammonium is well known, with different mechanisms being postulated. In this study the possibility to use ammonium loaded biochars in growing media, in comparison to other sorbents like natural zeolites was exploited. A spruce biochar and a poplar biochar, obtained by high temperature pyro-gasification, and a natural zeolite (chabazite) were loaded with ammonium by soaking in 0.5M ammonium sulphate. An incubation test and a plant growth trial were performed on the ammonium-enriched materials added to a peat based growing media, compared with (NH4)2SO4. The peat was able to quickly retain the ammonium added with both mineral fertiliser and biochars. The loaded biochars do not act as slow release N carriers; nevertheless, they promote plant nitrogen uptake. The zeolite strongly retained ammonium throughout the experiment leaving an amount of soluble nitrogen lower than plant requirements.