Production of pine sawdust biochar supporting phosphate-solubilizing bacteria as an alternative bioinoculant in Allium cepa L., culture

Abstract

We produced and characterised biochar made from Caribbean pine sawdust as raw material. The biochar (BC500) was used as biocompatible support to co-inoculate phosphate solubilizing bacteria (PSB) (BC500/PSB) on Allium cepa L., plants at a greenhouse scale for four months. The three biomaterials study included proximate analysis, elemental analysis, aromaticity analysis, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), adsorption studies at different pH and PSB stability as a function of time. The results indicated that BC500 is suitable as organic support or solid matrix to maintain the viability of PSB able to solubilise P from phosphate rock (PR). The biofertilizer (BC500/PSB) allows increasing germination, seedling growth, nutrient assimilation, and growth of Allium cepa L., because PSB immobilised on BC500 promoted nutrient mobilisation, particularly P, during cultivation of Allium cepa L., at pots scale. The two treatments to evaluate the biofertilizer (BC500/PSB) showed the highest concentrations of total P with 1.25 ± 0.13 and 1.38 ± 0.14 mg bulb−1 in A. cepa L. This work presents the benefits of a new product based on bacteria naturally associated with onion and an organic material (BC500) serving as a bacterial carrier that increases the adsorption area of highly reactive nutrients, reducing their leaching or precipitation with other nutrients and fixation to the solid matrix of the soil.

Biochar: An effective measure to strengthen phosphorus solubilizing microorganisms for remediation of heavy metal pollution in soil

“…Meanwhile, the rich nutrients of biochar itself can also guarantee the reproduction of microorganisms (Cooper et al, 2020). Blanco-Vargas et al (2022) also confirmed that biochar is an excellent biological inoculant to support the growth of phosphate-solubilizing bacteria. Therefore, the use of biochar to improve the efficiency of soil microbial remediation is a more effective strategy.…”

Use of biochar and a post-coagulation effluent as an adsorbent of malachite green, beneficial bacteria carrier, and seedling substrate for plants belonging to the poaceae family

“…Another production condition considered to improve the biochar quality was a pre-treatment, introducing it into an anaerobic hood to reduce the O 2 before the DRMM co-pyrolysis process at 300 and 500 °C. These systems involve a chemical catalyst that generates hydrogen; this gas combines with O 2 to form water and progressively reduces its concentration (Blanco-Vargas et al 2022 ). Although it is difficult to eliminate all the O 2 in an organic materials mixture, such as the one evaluated, it is possible to reduce it, allowing biochar production to be carried out under reduced oxygen conditions to decrease volatilisation losses and concentrate the solid products (Table 2 ).…”

“…Although it is difficult to eliminate all the O 2 in an organic materials mixture, such as the one evaluated, it is possible to reduce it, allowing biochar production to be carried out under reduced oxygen conditions to decrease volatilisation losses and concentrate the solid products (Table 2 ). Additionally, production costs decrease as it would not be necessary to continuously introduce an inert gas into the muffle to maintain 100% oxygen-free conditions (Moreno-Bayona et al 2019 ; Blanco-Vargas et al 2022 ).…”

“…Subsequently, Pseudo-first-order and Pseudo-second-order models were applied to evaluate which described best the MG adsorption process. The calculated parameters were the maximum amount of adsorbed dye (mg g −1 ) of biochar ( q e ), Pseudo-first-order adsorption coefficient ( k 1 ) and pseudo-second-order adsorption coefficient ( k 2 ) (Morales-Álvarez et al 2016 ; Castillo-Toro et al 2021 ; Blanco-Vargas et al 2022 ). Equations 4 and 5 describe the models: where qe is the amount of dye adsorbed at equilibrium (mg g −1 ), q is the dye adsorbed per gram of adsorbent (mg g −1 ), k is the pseudo-first-order adsorption coefficient (min −1 ), t is time (min).…”

“…In sustainable agriculture, biochar obtained by co-pyrolysis is destinated to soil conditioner, organic fertiliser, planting, and germination substrate in nurseries (Céspedes-Bernal et al 2021 ), improving the physical and chemical properties of the soil and promoting the biological activity of plants associated with systemic resistance to physical, chemical and biological factors (Arshad et al 2021 ; Medeiros et al 2021 ). Biochar also serves as a physical supporting material for beneficial microorganisms that promote plant growth and help decrease the excessive use of chemicals in the soil (Moreno-Bayona et al 2019 ; Blanco-Vargas et al 2022 ). At the environmental level, biochar serves as an adsorbent removing dyes, heavy metals, pesticides, hydrocarbons, and emerging pollutants, among others (Zeng et al 2018 ; Castillo-Toro et al 2021 ).…”