Biochar enhances soil interactions and the initial development of sugarcane

Abstract

The present study evaluated the effects of biochar derived from sugarcane straw on the physicochemical and biological properties of soil and the initial development of sugarcane. Microcosm and pot experiments were conducted over 60 days to monitor variables such as pH, water retention capacity, microbial activity, initial growth, and the metabolomic profile of the plant leaves. The results indicated that biochar increased the soil water retention capacity without significantly affecting the pH. The biochar significantly promoted root length and mass and favored the growth of the soil microbiota, as reflected by an increase in the amount of microbial biomass carbon. Metabolomic analysis of sugarcane leaves revealed that soil conditioning with biochar at application rates of 3 and 5% w/w led to increased concentrations of the amino acids isoleucine and valine, accompanied by a reduction in galactose, maltose, and glucose levels. Furthermore, biochar treatment resulted in a decrease in aconitic acid and an increase in acetic and succinic acid concentrations. These findings suggest that biochar may be a promising strategy for enhancing the productivity and sustainability of sugarcane cultivation.

Keywords: Biomass; Carbon; Metabolome; Microbiota; NMR.

Fig. 1

Schematic diagram of the experiment. The icons are reproduced from Flaticon with permission.

Fig. 2

- Micrographs of the solid fraction of the nutrient culture medium supplemented with 0% (a), 1% (b), 3% (c), and 5% w/w (d) biochar. Images (e-h) correspond to micrographs of the solid fraction of Martin culture medium with the addition of 0% (e), 1% (f), 3% (g), and 5% w/w (h) biochar, respectively. In the images, a variety of microorganisms can be observed, including cocci-shaped bacteria and fungal hyphae, indicated by the green arrows.

Fig. 3

(a) Plant height, (b) root length, fresh leaves (c), fresh root (d), leaves dry mass (e), and root dry mass (f) of sugarcane at 30 and 60 days after planting (DAP) in soil conditioned with biochar. Symbols with different letters indicate significant differences according to the Scott‒Knott test (p < 0.05). The photographs inserted illustrate the plants at the time of evaluation, 30 DAP.

Fig. 4

Stacked plot of ¹H NMR (KH₂PO₄ buffer in D₂O/Methanol-d₄ 1:1, 600 MHz) spectra of extracts from sugarcane leaves cultivated in soil containing biochar at 0% (CK), 1% (BC1), 3% (BC3), and 5% w/w (BC5).

Fig. 5

HCA dendrogram associated with the heatmap of the metabolites quantified in the extracts of sugarcane leaves cultivated in soil (control, CK) and soil containing biochar at 1 (BC1), 3 (BC3), and 5 (BC5) % w/w. The color of each section changes from dark blue to crimson in the heatmap, corresponding to a change in the concentration of each metabolite from low to high. Metabolites marked with an * were not statistically significant, with an FDR < 0.05.

Fig. 6

Box-Whisker plot for the significantly different metabolites (p < 0.05) quantified in the extracts of sugarcane leaves. The metabolites that showed significant differences according to ANOVA and post hoc analysis were selected, and their concentrations were plotted across the four experimental conditions: CK (control, soil only); BC1 (soil containing 1% w/w biochar); BC3 (soil containing 3% w/w biochar); and BC5 (soil containing 5% w/w biochar).