| Abstract: | Utilization of day fixed ammonium nitrogen by ryegrass (Lolium multiflorum) In a pot experiment with ryegrass (Lolium multiflorum) the availability of ammonium fixed by clay minerals of a soil treated with 15NH4 has been studied. The following results were obtained: After the treatment of the soil with labelled NH4+ it contained 62.7 mg fixed NH4-N/kg soil including 4.5 mg 15NH4-N/kg soil. Nitrogen uptake of ryegrass and N turnover reactions in the soil reduced this content of 15NH-N to about 0.9 mg/kg soil. This shows, that about 80 % of the fixed 15NH4+ had been released through out a growing period comprising 3 cuts, a part of which was taken up by the plants. From the native fixed ammonium 3.3 to 4.8 % were released. |
