Application of cotton straw biochar and compound Bacillus biofertilizer decrease the bioavailability of soil cd through impacting soil bacteria

Abstract

Background Cd seriously threatens soil environment, remedying Cd in farmland and clearing the response of soil environment to modifiers in Cd-contaminated soils is necessary. In this study, the effects of cotton straw biochar and compound Bacillus biofertilizer used as modifiers on the biochemical properties, enzyme activity, and microbial diversity in Cd-contaminated soils (1, 2, and 4 mg·kg−1) were investigated. Results The results showed that both cotton straw biochar and compound Bacillus biofertilizer could improve the soil chemical characteristics, including the increase of soil C/N ratio, electrical conductance (EC) and pH, and the most important decrease of soil available Cd content by 60.24% and 74.34%, respectively (P < 0.05). On the other hand, adding cotton straw biochar and compound Bacillus biofertilizer in Cd stressed soil also improved soil biological characteristics. Among them, cotton straw biochar mainly through increasing soil alkaline phosphatase activity and improve bacteria abundance, compound Bacillus biofertilizer by increasing soil invertase, alkaline phosphatase, catalase, and urease activity increased bacterial community diversity. On the whole, the decrease of soil available Cd was mainly caused by the increase of soil pH, C/N, urease and alkaline phosphatase activities, and the relative abundance of Acidobacteria and Proteobacteria. Conclusions In summary, the applications of cotton straw biochar and compound Bacillus biofertilizer could decrease soil available Cd concentration, increase soil bacterial community diversity and functions metabolism, and reduce the damage of Cd stress, compared with cotton straw biochar, compound Bacillus biofertilizer was more effective in immobilizing Cd and improving soil environmental quality.

Bacteria-loaded biochar for the immobilization of cadmium in an alkaline-polluted soil

“…S3a). Similar observations were also reported (Zhu et al, 2022a). An increased soil pH stimulates the formation of more precipitation complexes, which enhances Cd passivation and decreases Cd bioavailability (Quilliam et al, 2013) (Bandick and Dick, 1999).…”

“…The combination of biochar and microorganisms combines the merits of the two methods and avoids the de ciency caused by the use of biochar or bacteria alone, thus achieving e cient reduction in Cd motility by direct immobilization of Cd, improvement of soil quality and the survival of exogenous bacteria, and enrichment of special microbes (Ma et al, 2020;Qi et al, 2021). Among these bacteria, biochar and species within the genus Bacillus have been reported to effectively reduce Cd mobility and increase soil pH and enzyme activities (Mei et al, 2022;Zhu et al, 2022a). As previously stated, the mechanisms involving Cd immobilization by biochar or bacteria alone have been clearly studied.…”

Growth, development and nitrogen nutrition of colored cotton cv. BRS Topázio under sustainably-constructed soil

“…Significant differences were observed between substrates for all soil fertility indicators (Table 4). The use of bovine manure in the substrate, the inoculation of cotton seeds with the N 2 -fixing bacterium A. brasilense, and the application of anaerobically-made biofertilizer caused a significant improvement in the indicators of soil acidity, availability of essential mineral nutrients, and organic matter compared with poor soil fertilized with chemical fertilizers, as also found in other studies (SHARMA; VASUDEVA, 2005;LIMA et al, 2007;SCHWEINSBERG-MICKAN;MÜLLER, 2009;OBIA et al, 2015;GALINDO et al, 2017;SILVA et al, 2019;ZHU et al, 2022). Moreover, diazotrophic bacteria also contribute to increase the soluble P available to plants in the soil (SILVA et al, 2006;BUSATO et al, 2012).…”

Acid-Modified Biochar Impacts on Soil Properties and Biochemical Characteristics of Crops Grown in Saline-Sodic Soils

“…Duan et al [55] studied the effect of biochar addition to salt-affected soil on water movement and found that the transition rate of the soil moisture increased after biochar supplementation to the soil. From another view, [56] found that the application of cotton stalk biochar increased the soil EC around 45% compared to the control, but according to this study it was found that the application of cotton biochar caused a migration of salts through the soil profile in both seasons, recording 22.37% and 23.87% in maize and wheat seasons compared to 21.14% and 22.17% with the control treatment, whereas the modified cotton biochar CSMB treatment reached 23.78% and 31.36% in maize and wheat plants, respectively. Overall changes in ESP were observed with the application of biochar.…”