Abstract
Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) are key drivers of nitrification in rainfed soil ecosystems. However, within a semi-arid region, the influence of different soil amendments on the composition of soil AOA and AOB communities and soil properties of rainfed maize is still unclear. Therefore, in this study, the abundance, diversity, and composition of AOA and AOB communities and the potential nitrification activity (PNA) was investigated across five soil treatments: no fertilization (NA), urea fertilizer (CF), cow manure (SM), corn stalk (MS), and cow manure + urea fertilizer (SC). The AOB amoA gene copy number was influenced significantly by fertilization treatments. The AOB community was dominated by Nitrosospira cluster 3b under the CF and SC treatments, and the AOA community was dominated by Nitrososphaera Group I.1b under the CF and NA amendments; however, manure treatments (SM, MS, and SC) did not exhibit such influence. Network analysis revealed the positive impact of some hub taxonomy on the abundance of ammonia oxidizers. Soil pH, NO3−-N, Module 3, biomass, and AOB abundance were the major variables that influenced the potential nitrification activity (PNA) within structural equation modeling. PNA increased by 142.98–226.5% under the treatments CF, SC, SM, and MS compared to NA. In contrast to AOA, AOB contributed dominantly to PNA. Our study highlights the crucial role of bacterial communities in promoting sustainable agricultural production in calcareous soils in semi-arid loess plateau environments.
Highlights
We discovered that NO3 − -N is a suitable soil nutrient for maintaining metabolic activities in the link between the ammonia-oxidizing bacteria (AOB) amoA gene, module 3, potential nitrification activity (PNA), and biomass [53,54,56]
Wang et al [61] found that N-rich soils have P-releasing enzymes that increase P and N cycling, which is consistent with our results; we discovered a significant relationship between PNA and AP
The results of this study show that AOB contributes more to nitrification in agricultural calcareous soils than ammonia-oxidizing archaea (AOA)
Summary
Corn is predominantly cultivated within this region, and farmers rely heavily on both organic and inorganic fertilizers in their farming systems to achieve sustainable agriculture. An enormous corn harvest is generally achieved with the plastic mulch technique which enhances both soil humidity and temperature [2] and elevated N fertilizer applications [3]. Excessive application of inorganic fertilizer (urea) has dire consequences on the abundance and diversity of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) within the soil. The integrated use of cow manure in combination with minimal urea and corn stalk has the advantage of providing a long-lasting effect on the AOA and AOB community and abundance [7,8,9]
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