Abstract: The aim of this study was to investigate the effect of different fertilization regimes on contents and dynamics of soil fixed ammonium in the low reach of Liaohe River plain based on a longterm insitu experiment (22 years), including six treatments, i.e. CK (unfertilized control), M (recycled pig manure), NP (mineral fertilizer NP), NPK (mineral fertilizer NPK), NPK+M (recycled pig manure with mineral fertilizer NPK), and PK (mineral fertilizer PK). The results showed that the contents of soil fixed ammonium in the different fertilization treatments all decreased and then leveled off. Compared to the initial value, the release of soil fixed ammonium ranged from 18.0% to 38.7% in the different treatments. Application of nitrogen fertilizer would reduce the content of soil fixed ammonium, while potassium could retard the release of fixed ammonium. Recycled pig manure applied alone had no significant effect on the content of fixed ammonium, whereas combined application of recycled pig manure and NPK could increase crop yield, as well as maintain a high level of fixed ammonium, helping to build a great soil nitrogen pool. Therefore, it can be suggested that application of recycled manure coupled with N, P and K fertilizers is an optimum fertilization regime in this region.

Key words: endophyte, Achnatherum sibiricum, total phenolic, lignin, methyl jasmonate.