The Effects of Organic and Mineral Fertilization on Soil Enzyme Activities and Bacterial Community in the Below- and Above-Ground Parts of Wheat

Abstract

Bacterial community and soil enzymatic activity depend on soil and management conditions. Fertilization is an important approach to maintain and enhance enzyme activities and microbial community diversity. Although the effects of fertilizer application on soil microbial community and related parameters are explored, the effects on the soil microbiome associated with those of wheat plant organs, including those associated with roots and spikelets, are not well-known. Therefore, in this study, by using a sequencing approach, we assessed the effects of inorganic fertilizers, manure, and biochar on soil enzyme activities, bacterial community diversity and structure in the bulk soil, rhizosphere, roots, and spikelet of wheat (Triticumaestivum L.). For this, different treatment biochar (BC), manure (OM), low mineral fertilizer (HL), high mineral fertilizer (HF), and no fertilizer (FO) were used for the enzyme activities and bacterial community structure diversity tested. The result showed that organic amendment application increased total nitrogen, soil available phosphorus, and potassium compared to inorganic fertilizer and control, especially in the rhizosphere. Enzyme activities were generally higher in the rhizosphere than in the bulk soil and organic amendments increased activities of acid phosphatase (AcP), β-1,4-N-acetyl-glucosaminidase (NAG), and phenol oxydase (PhOx). Compared with soil and rhizosphere, bacterial diversity was lower in wheat roots and evenlower in the spikelet. From the bulk soil, rhizosphere to roots, the fertilization regimes maintained bacterial diversity, while organic amendment increased bacterial diversity in the spikelet. Fertilization regimes significantly influenced the relative abundances of 74 genera across 12 phyla in the four compartments. Interestingly, the relative abundance of Proteobacteria (Citrobacter, Pantoea, Pseudomonas, and unclassified Enterobacteriaceae) in the spikelet was decreased by increasing inorganic fertilizer and further by manure and biochar, whereas those of Actinobacteria (Microbacterium and an unclassified Microbacteriaceae) and Bacteroidetes (Hymenobacter and Chitinophagaceae) were increased. The results suggest that potential bacterial functions of both roots and above-ground parts of wheat would be changed by different organic amendment regimes (manure and biochar).

Defining the wheat microbiome: Towards microbiome-facilitated crop production

“… Type Factor Reference Anthropogenic Exogenous compounds (fungicide) [18] , [19] Exogenous compounds (glyphosate) [20] Exogenous compounds (insecticides) [21] Exogenous compounds (phosphine fumigation of stored wheat grains) [22] Exogenous compounds (plastic mulch film residues) [23] Fertilization [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] Inoculation of biocontrol agent [26] , [34] , [35] Land use [36] , [37] , [38] Management type [39] , [40] , [41] Overhead irrigation [42] Rotation [43] , [44] , [45] , [46] , [47] , [48] Tillage [40] , …”

“…Members of Acidobacteria and Planctomycetes were significantly depleted in treatments receiving inorganic N and 16S rRNA gene-predicted functional structure was also impacted [27] . In another study the use of organic amendments such as biochar and manure were compared to the use of mineral fertilization on above (spikelet) and belowground (rhizosphere and root) bacterial communities, with significant changes in their structure and diversity [24] . In addition, Chen et al [25] found that nitrogen fertilization affected rhizosphere bacterial communities isolated from wheat plants during tillering but not during jointing and ripening.…”

“…It is well known that differences in soil physical and chemical properties drive microbiome community structure in wheat. Amadou et al [24] observed that the amendment of soil with biochar and manure as well as the addition of inorganic mineral fertilizers changed soil properties, in particular NH 4 + content, and these impacted above (spikelet) and belowground (rhizosphere and root) bacterial community structure. Organic amendments can improve water retention and are associated with increased acid phosphatase, β-1,4- N -acetyl-glucosaminidase and phenol oxidase activity, whereas inorganic fertilizers lower the pH, increasing nutrient assimilability.…”

“…Triticum (MoT), causal agents of Fusarium head blight (FHB) and wheat blast, respectively. However, it is known that bacterial diversity is lower in spikes than in the rhizosphere [24] . In addition, Rojas et al [64] observed that when wheat is infected by Fusarium , a shift in fungal endophytic community colonization dynamics occurs.…”

Effects of Manure and Chemical Fertilizer on Bacterial Community Structure and Soil Enzyme Activities in North China

“…The results indicated that soil enzyme activity was directly affected by the amount of fertilizer applicated. Previous studies have shown that manure application was of paramount importance to improve soil enzyme activities, which significantly increased enzyme activities more than that of chemical fertilizer application [46].…”