Dominance of archaeal ammonia-oxidizers in soil nitrification across different soil types and fertilities in North China plain

Abstract

Microbially mediated soil nitrification process was largely limited by ammonia-oxidizing archaea (AOA) and bacteria (AOB), which further affect nitrogen (N) loss and retention with concomitant impacts on both crop productivity and environment. However, the spatial distribution of ammonia-oxidizers and their varying contributions to soil nitrification activity at provincial scale are poorly explored. 135 agricultural soils across different soil types and fertility conditions were collected from Henan province in North China Plain to draw the map of soil AOA and AOB abundance with quantitative PCR analysis. Soil nitrification potential (NP) and the relative contribution of AOA and AOB to NP that recovers after acetylene inactivation were essentially determined among the five major soil types. The abundance of ammonia-oxidizers, which was positively and significantly related with pH, was obviously predominated by AOA with AOA/AOB ranging 1.96–9.79 at provincial scale. AOA contributed more (at 60%–79%) to soil nitrification in acidic and neutral soils (Lime concretion black soil, Yellow-cinnamon soil, Paddy soil and Cinnamon soil) with significant relationships with its higher abundance, pH, soil organic carbon and ammonium nitrogen. On the contrary, the even contribution of AOB compared with AOA in alkaline Fulvo-aquic soil showed poor relationship with its abundance but was strongly affected by soil N availability. In summary, AOA even with lower abundance showed stronger function in acidic and ammonia-limited soil environments, but AOB with higher abundance tends to be the leader of soil nitrification in alkaline and substrate-rich soils of Henan province.