Effect of Different Nitrogen Rates on the Nitrification Potential and Abundance of Ammonia-oxidizer in Intercropping Maize Soils

Abstract

The objectives of this study were to explore the effects of different nitrogen rates on the nitrification potential in intercropping maize soils. The experiment included two plantation types (maize monocropping and intercropping maize and potato) and four nitrogen levels (N0: no fertilizer treatment, N1: 1/2 conventional fertilizer treatment, N2: conventional fertilizer treatment, N3: 3/2 conventional fertilizer treatment). Abundance of AOA and AOB was analyzed with real-time quantitative PCR (Q-PCR) and soil properties were also measured. Results of this study suggested that the PNF of soils, the abundance of AOA and AOB were increased with increasing N fertilization in conventional fertilizer range, and there was no significant difference between N2 and N3 treatments. The influences of intercropping on PNF, AOA and AOB were associated with N application rates and crop growth period, as well as the benefits of ammonia oxidizer and nitrification of intercropping on N1 level. Fertilization was obviously the main driving force of the PNF, correlation analysis indicated that water content was the main environmental factor affecting the nitrification potential. Nitrification potential in maize and potato intercropping soils exhibited significant positive correlations with AOA and AOB amoA gene abundance. Maize and potato intercropping could decrease the abundance of AOA and AOB, but it resulted in dominance of AOB among nitrification bacteria in these soils. In conclusion, N fertilizer and intercropping could affect both soil nitrogen internal cycling process and the abundance of AOA and AOB, which further affected soil environmental quality.