Dairy Effluent-Saturated Biochar Alters Microbial Communities and Enhances Bermudagrass Growth and Soil Fertility

Abstract

Recently, biochar has been proposed for various agronomic applications including improved plant growth and soil fertility. In this study, the effects of dairy effluent-saturated (SBC) and unsaturated wood-derived biochar (UBC) on Bermudagrass (Cynodon spp.) growth, soil fertility and microbial communities were investigated in a greenhouse pot study. SBC and UBC were mixed with sandy loam soil at various loading rates (0, 1, 2, 4, and 8%) to grow Bermudagrass for 10 weeks. Soil physicochemical properties and plant growth measurements were taken, followed by 16S rRNA (V3-V4) amplicon sequencing of soil bacterial communities. Amendment of SBC to soil altered the soil physicochemical properties and increased the concentrations of N and P in the soil at 2 to 8% loading rates compared to UBC treated soil. The addition of SBC to soil also increased the overall plant biomass compared to UBC with more effects on aboveground biomass. Differential abundance analysis of taxa showed enrichment of Proteobacteria in UBC-amended soil, whereas Firmicutes and Nitrospirae were abundant in SBC-amended soil. Interestingly, enrichment of photosynthetic and N-fixing bacteria was observed in both SBC and UBC-amended soils after 10 weeks of treatments. However, oxidative phosphorylation and biotin metabolisms were found to be more abundant in SBC-amended soil compared to UBC-amended soil. Overall, our study suggested that amendment of SBC to soil resulted in enhanced soil nutrients, microbial capacity and Bermudagrass growth than that of UBC. Therefore, application of SBC to soil in field trials would be merited to identify sustainable and effective practices for enhancing plant growth, soil fertility and soil bacterial community.

Dairy Effluent-Saturated Biochar’s Short-Term Effects on Vigna unguiculata and Cynodon dactylon Performance and Soil Properties

“…This partially agrees with a study which reported similar BC effect on P soil content despite an overall negative and positive effect on T. incarnatum and L. multiflorum performance, respectively [ 22 ]. Furthermore, our results did not agree with other studies which reported that P content increased when wood BC was applied in an experiment where C. dactylon was grown in a sandy loam [ 21 ]. Phosphorus binds to BC particles, and its greater presence could be positive in the long term for soil health and plant growth.…”

“…However, some partial negative effects were observed for herbage C% (−2%) and production (−27%) at the first and second cut, respectively, independently of the applied BC type and saturation treatment. These results did not agree with Artiola et al [ 33 ] and Niraula et al [ 21 ], who reported an overall increase in the growth of C. dactylon when wood BC was applied. Moreover, the application of either saturated wood BC positively affected C. dactylon at all assayed loading rates (1 to 8%) and unsaturated wood BC had a positive impact only at the highest loading rate (8%) [ 21 ].…”

“…These results did not agree with Artiola et al [ 33 ] and Niraula et al [ 21 ], who reported an overall increase in the growth of C. dactylon when wood BC was applied. Moreover, the application of either saturated wood BC positively affected C. dactylon at all assayed loading rates (1 to 8%) and unsaturated wood BC had a positive impact only at the highest loading rate (8%) [ 21 ]. In our study, regardless of the BC type, the saturation treatment with dairy effluent did not show a role in any forage performance.…”

“…For instance, the addition of enriched BC can improve soil quality (i.e., organic matter and macronutrients) and the biomass yield of maize [ 12 ]. Enriched BC increases soil nutrients (e.g., N and P) and can result in greater C. dactylon biomass in the short term [ 21 ]. Likewise, positive short-term effects on Lolium multiflorum growth occur when different types of saturated BCs are applied, while the same BC (enriched or not) has a negative effect on Trifolium incarnatum performance, as well as varied effects on soil parameters [ 22 ].…”

Biochar and Dairy Manure Amendment Effects on Cynodon dactylon Performance and Soil Properties

“…Artiola et al [ 22 ] and Niraula et al [ 23 ] reported a positive effect on C. dactylon growth when wood BC was applied in sandy loam soil and loamy sand soil, respectively, whereas Nystrom [ 24 ] reported a neutral effect when sorghum-derived BC was applied both in a greenhouse experiment with different soil textures and in a field trial in a sandy loam soil. Manure amendment had a positive effect not only on C. dactylon [ 25 , 26 ] but also on Festuca arundinacea and Digitaria erianta [ 27 ] forage yield in sandy loam and sandy clay loam soil, respectively.…”