Soil Amendments with Lignocellulosic Residues of Biorefinery Processes Affect Soil Organic Matter Accumulation and Microbial Growth

The development of soil microbiota and the chemical composition of soil organic matter (SOM) were studied in a 180 day incubation experiment upon addition of a characterized lignocellulosic biorefinery residue (BYP) at two different rates. The microbial growth was studied by PLFA analysis after 30, 60, and 180 days, while SOM molecular composition was assessed by thermochemolysis at the end of the trial. Soil amendments with BYP induced a well differentiated microbial community. However, the overall microbial development significantly decreased over the experimental time due to a lesser availability of decomposable C to microorganisms. The reduced C accessibility was related to the progressively higher SOM recalcitrance with increasing BYP rates and was attributed to selective accumulation into the stable SOM fraction of hydrophobic compounds which prevented further BYP mineralization by protecting BYP from microbial activity. Our findings indicate that amendments with lignin-rich residues from biorefinery processes may promote the stabilization of humified molecules in soils, thus leading to a net C accumulation in soils. © 2020 American Chemical Society.PON03PE_00107_0

Improved phosphorus fertilisation efficiency of wood ash by fungal strains<em> Penicillium</em> sp. PK112 and <em>Trichoderma harzianum</em> OMG08 on acidic soil

International audienceEffective recycling of phosphorus (P) remains a critical issue in sustainable agriculture. Wood ash represents valuable soil amendment and potential source of P for agriculture, but its solubility and subsequent P-fertilisation efficiency is extremely low. This study tested fungal inoculants (Penicillium sp. PK112 and Trichoderma harzianum OMG08) applied alone and in combination with wood ash on P-limiting acidic soil to determine if they can improve P-nutrition in maize. Wood ash alone did not have any significant P-fertilising effect. Application of both inoculants, when combined with wood ash, led to significant increment of plant-available P content in soil, increased P uptake by maize plants and consequently to higher production of maize shoot biomass. Both inoculants suppressed overall microbial activity in soil as determined by the activity of dehydrogenase, alkaline phosphatase and microbial P content. Only T. harzianum led to higher activity of soil acid phosphatase. This study demonstrated that tested strains may be co-applied with wood ash to improve its Pfertilisation efficiency. The positive influence of inoculants on P availability was mainly due to stronger acidification of rhizosphere and decreased content of microbial P. However, both effects seemed to be hindered by the P sorption capacity of the soil in the case of inoculation without wood ash. Such findings may lead to development of novel formulations of recycled fertiliser products and boost nutrient recycling in agriculture

Utilization of Coal and Biomass Ash

Sustainable utilization of the ash generated from the combustion of coal or biomass is a big challenge for the power industry. Huge quantities of ash are generated and, in general, they are disposed-off in ash ponds. However, recent regulatory requirements demand 100% utilization of ash. So many new areas of ash utilization are being explored by the researchers and ash managers. Bulk utilization sectors are cement industry, construction, bricks, landfill, mine back filling, and soil amendment for growing plants. Efforts to enhance the use in value-added low-volume sectors like fertilizer, cenosphere, catalyst support, zeolites, aerogels, and so on are continuously evolving. The heterogeneity of the ash properties is one of the main challenges for advocating a generalized utilization pattern of the ash. Biomass has some typical properties that limit its use for some sectors. However, beneficiation of both coal and biomass ash and use of other additives could improve the suitability of the ashes to multifarious uses