Linking bacterial community to aggregate fractions with organic amendments in a sandy soil

Abstract

Soil aggregates provide microhabitats for microorganisms. However, the bacterial communities within various aggregate size fractions under organic amendments have rarely been evaluated especially in sandy soils. A field experiment involving addition of biogas residue (BR), pig manure (PM), biochar (BC), and straw (ST) of a sandy soil was performed to determine the structure of the bacterial community in aggregate size fractions by using high‐throughput sequencing. We found that organic amendments change soil aggregate fractions and nutrient content, alter bacterial diversity and composition, and contribute to the predicted bacterial functions. The BR increased bacterial α‐diversity in <0.25‐mm aggregates. The Nitrospirae was abundant in almost all aggregate sizes, whereas the abundance of Actinobacteria decreased in most of aggregates following BR addition. The PM amendment primarily facilitated the growth of Bacteroidetes and inhibited the growth of Acidobacteria and Chloroflexi in 0.25‐ to 2‐mm aggregates, whereas bacterial α‐diversity was decreased in the >0.25‐mm aggregates. The BC treatment decreased the bacterial α‐diversity in the <0.25‐mm aggregates and the Gemmatimonadetes abundance in all <2‐mm aggregates, but the Actinobacteria abundance was significantly increased in the >0.053‐mm aggregates. Collectively, the effects of organic amendments on the bacterial community varied greatly depending on type of amendments and aggregate size. The BR supported highly diverse bacterial taxa in the <0.25‐mm aggregates, whereas it proliferated N cycling‐related bacteria in all aggregates. Our results highlight the links between bacterial community and aggregate size fractions in sandy soils depending on organic amendments.

Ecological network analysis to assess the restoration success of disturbed mine soil in Zoucheng, China

“…However, as the plots under study have been subjected to intensive farming activities since they were reclaimed, it was hard to acknowledge which changes in the key soil attributes which can be modified through both land reclamation and farming activities (Huo et al, 2018), is a relevant proxy to understand how a soil behaves from the physical (e.g., Lu & Likos, 2004), chemical (Saygin et al, 2017)), and biological standpoint (Chaganti & Crohn, 2015). In fact, the assessment of soil aggregates can shed light on the ability of soils to provide habitat to SMCs (Dai et al, 2019). We did not quantify the effect of land reclamation on soil aggregates, which is a limitation to the study, but we envisage that future work investigating the effect of land reclamation on key soil attributes should include soil aggregates in the analysis.…”

Microscale heterogeneity of soil bacterial communities under long-term fertilizations in fluvo-aquic soils

“…The aggregate size class with high complexity of bacterial groups could provide biological buffering and thus was potentially stable after 39-year fertilizations. The less stable of network in smaller aggregates was due to the lack of physical protection for microbes among small particles (Dai et al, 2019). Meanwhile, the modularity in macroaggregate was significantly lower than that in smaller fractions (Table 1), indicating that macroaggregate had higher niche overlap than microaggregate and silt + clay fractions.…”

“…Additionally, the numbers of biomarkers in macroaggregates and microaggregates were 60 and 59, respectively, which were evidently higher than in silt + clay (52 biomarkers). This indicated that the bacterial communities in silt + clay fractions were less sensitive to long-term fertilizations than those in larger aggregates (Yang et al, 2007;Dai et al, 2019). The lower vitality of bacterial communities in silt and clay fraction also explained why the nutrient turnover was much slower in the silt + clay aggregate size class than in larger aggregates.…”

Temperature sensitivity of soil organic matter mineralization decreases with long‐term N fertilization: Evidence from four Q10 estimation approaches

“…The SOM accumulation upon N fertilization occurs primarily in occluded particulate organic matter (Zak, Freedman, Upchurch, Steffens, & Kögel‐Knabner, ). Long‐term mineral and/or organic N fertilization facilitates C sequestration by increasing soil С input from larger plant biomass and manure (Dai et al, ; Liang et al, ; Zang, Qian, et al, ), and by reducing SOM decomposition (Liu et al, ; Xiao, Zang, Ge, et al, ; Xiao, Zang, Liu, et al, ). Organic N stimulates SOM decomposition more than mineral N (Chen et al, ) due to an increase of microbial activity and more necromass production (Liang et al, ).…”