Biochar and Sulphur Enriched Digestate: Utilization of Agriculture Associated Waste Products for Improved Soil Carbon and Nitrogen Content, Microbial Activity, and Plant Growth

Abstract

A number of agriculture residues may be used either directly or after suitable treatment as amendments to improve soil quality. Such materials include biochar made of agriculture residues, digestate or elemental sulphur obtained from biogas desulphurisation. The joint use of these materials via pre-incubation may be more advantageous than only mixing prior the application to soil. In this study, digestates were mixed with amendments and incubated for 6 weeks before application to soil in a short-term pot experiment with lettuce (Lactuca sativa). The following treatments were tested: control digestate, digestate + biochar, digestate + elemental sulphur, digestate + biochar + elemental sulphur. The biochar-enriched digestate significantly increased soil microbial biomass, soil C:N, fresh above ground biomass, fresh and dry root biomass. Elemental sulphur-enriched digestate caused highest arylsulfatase and phosphatase, increased urease, microbial biomass in soil and fresh root biomass. Amendment of digestate + biochar + sulphur led to the significantly highest total soil carbon, microbial biomass, β-glucosidase, urease, and increased C:N ratio, arylsulfatase in soil and root biomass. It mitigated the adverse effect of either biochar or elemental sulphur on soil respiration. Properties of digestates were apparently affected by pre-incubation. This approach in digestate fertilizer production may contribute to sustainable farming.

Effects of Combined Application of Solid Pyrolysis Products and Digestate on Selected Soil Properties of Arenosol and Plant Growth and Composition in Laboratory Experiments

“…In general, the presence of digestate resulted in higher plant yield in samples treated with WBCxAD and ABCxAD compared to the WBC and ABC treatments. Our results, in agreement with similar data recently reported for lettuce (Lactuca sativa) [80], show that the digestate-supplemented ABC is more effective in the improvement of the air-dry mass of plants than digestate-free biochar treatments (p ≤ 0.009).…”

“…Based on the positive combined effects observed in the co-application of biochar with chemical fertilizers [55], it appears achievable to gain mutual benefits from the combined application of biochar with anaerobic digestate. Thus, the co-application of biochar and digestate lead to improvements in several soil quality properties, but have a negative effect on soil respiration [80]. As for the beneficial effects on crops, the combined use of biochar with liquid digestate has been found to be favorable in increasing fruit yield (fruit number and weight) and quality (sugar content and consistency) in organic tomato production [81].…”

“…As for the beneficial effects on crops, the combined use of biochar with liquid digestate has been found to be favorable in increasing fruit yield (fruit number and weight) and quality (sugar content and consistency) in organic tomato production [81]. It has also elevated the biomass production of lettuce [80], and treatments with combinations of wood-based biochars and liquid or solid fractions of anaerobic digestates achieved yields comparable to the treatment using a commercial fertilizer also on lettuce and two other vegetables (kale and rocket salad) [59]. In addition, the combined application of biochar and anaerobic digestate resulted in improved crop performances (number of leaves and total branches, plant dry weight) and the final essential oil content in the cultivated aromatic plant rose-scented geranium [82].…”

Carbon-enriched organic amendments differently affect the soil chemical, biological properties and plant biomass in a cultivation time-dependent manner

“…The technology of manure composted with biochar may prolong the fertilizing effects of both amendments due to the potential of biochar in slow release of nutrients and hence aiding in plant nutrition [21]. Biochar-manure mixture has been reported to improve total soil carbon, nitrogen, bulk density and impacted the availability of nutrient macro-and microelements differently compared to the sole manure treatment [22,23]. It has been established that the shortterm effects of biochar-compost increases the contents of macro-and microelements after soil application [24].…”

Co-composting of cattle manure with biochar and elemental sulphur and its effects on manure quality, plant biomass and microbiological characteristics of post-harvest soil

“…( Mahimairaja et al., 1994b ; de la Fuente et al., 2007 ; Godlewska, 2018b ), and thus has left room for further studies. Moreover, the amendment of co-composted manure with elemental S may significantly alter soil enzyme activity ( Malik et al., 2021 ), with a putative benefit of increased rate of nutrient transformation via enhancement of microbial activity and abundance by combination of external organic matter and elemental S amendment ( Hammerschmiedt et al., 2021 ; Malik et al., 2021 ). Biochar addition to soil was also referred to affect activity of nutrient-transforming enzymes in soil not only negatively ( Li et al., 2018 ; Song et al., 2019 ), but also positively ( Azeem et al., 2019 ; Zhang et al., 2021 ).…”