Feasibility of Nitrogen-Enriched Chars as Circular Fertilizers

Keskinen, Riikka; Nikama, Johanna; Kaseva, Janne; Rasa, Kimmo

doi:10.1007/s12649-021-01471-5

Cited by 9 publications

(3 citation statements)

References 49 publications

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“…The total N present in the developed lignorea was 30–35%, estimated through KELPLUS instrument. Similarly, ref estimated total N in chars before and after loading N using the Kjeldahl method. Ref reported the nitrogen content was higher in nanozeourea (28%N) compared to zeourea.…”

Section: Results and Discussionmentioning

confidence: 99%

Urea–Lignin/Chitosan Nanocomposite as Slow-Release Nanofertilizer

Latha

Subramanian

Raja

et al. 2023

ACS Agric. Sci. Technol.

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Urea is a universal fertilizer, but its use efficiency hardly exceeds 30−35%, and more than 70% is lost to the environment, causing eutrophication in aquatic systems. This research focuses on encapsulating urea molecules using a ligninchitosan composite. The nanocomposite was developed as a suitable carrier for entrapping nitrogenous fertilizer. Coconut coir contains plenty of lignin, which was extracted using the organosolv process by using ethanol as a solvent. Organosolv lignin (OSL) yielded spherical lignin nanoparticles (LNPs) via the solvent displacement method. Finally, a nitrogen source was loaded into the chitosan/lignin nanocomposite fertilizer (lignorea), which consists of LNPs, chitosan, and a cross-linker. The nanocomposite was characterized using PSA, SEM, TEM, UV−vis, FTIR, and XRD. The morphology of the OSL and LNPs was examined under SEM (626 ± 40 nm) and TEM (26 ± 9 nm). The noncrystallinity of both lignin and crystallinity after entrapment in nanocomposite was validated by XRD. The specific functional group pertaining to the lignin backbone had aromatic vibrations at 1511 cm −1 (OSL) and 1507 cm −1 (LNPs), and the presence of an amide peak after loading N was observed in FTIR. The lignin samples have their corresponding spectral absorbance at 281 and 288 nm wavelengths obtained in UV−vis. The size and stability of the extracted OSL and LNPs were verified by a particle size analyzer and zeta potential, respectively. The compatibility and interactions of the developed nanofertilizer were confirmed with molecular modeling and simulation. The developed nanofertilizer has total nitrogen of 30−35% which slowly releases up to 15 days in the soil. The study clearly suggests that lignin with chitosan served as a perfect template to hold and release N in a regulated pattern that collectively contributes to improved N use efficiency.

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Section: Results and Discussionmentioning

confidence: 99%

Urea–Lignin/Chitosan Nanocomposite as Slow-Release Nanofertilizer

Latha

Subramanian

Raja

et al. 2023

ACS Agric. Sci. Technol.

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“…The N enrichment may be the result of N sorption or microbial N retention on the biochar surface, but this was not su cient to affect the C:N ratio of the growing medium blend with biochar nor the other N related characteristics. In general, the N sorption capacity of biochars and the amounts of N retained within biochars in bioavailable form are small (Keskinen et al 2021;Rasse et al 2022).…”

Section: Discussionmentioning

confidence: 99%

End-of-life stage of renewable growing media with biochar versus spent peat or mineral wool

Vandecasteele,

Similon,

Moelants

et al. 2023

Nutr Cycl Agroecosyst

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The composition of horticultural substrates for soilless greenhouse cultivation directly affects the sustainability of the cropping system but has also an indirect effect through the end-of-life of the spent media. Biochar amendment in growing media as bulk material and source of nutrients may improve the sustainability of controlled-environment agriculture. Horticultural substrates at the end of soilless strawberry and tomato cultivation were compared in 6 trials at commercial scale. Conventional mineral wool and peat-based blends were compared with peat-reduced and peat-free organic blends with or without 10 vol% biochar. Nutrients, C stability of the growing media and their value as soil improver were measured. The organic growing media had a high potential for reuse and for C storage. Spent mineral wool was signi cantly richer in total P, K, Mg and Ca and signi cantly lower in organic C content and C stability than the other blends, with a clearly lower value as soil improver than the organic blends. Biochar amendment in renewable organic blends increases its value as soil improver and the potential for reuse: adding 10 vol% biochar in the blend signi cantly increased the C content by 8% and the C:N ratio of the spent growing media but not the C stability. The pH of the biochar in the growing media decreased from 9.1 to 6.2 due the cultivation while the CEC increased. This research illustrates the feasibility of using biomass and biochar in cascade, i.e., rst as growing medium, and nally as a C-rich soil improver.

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“…Increase in NUE with BCF has largely been attributed to a putative slow-release effect that biochar matrices have on N fertilizers (Cai et al 2016;Dong et al 2019;Ibrahim et al 2020;Manikandan and Subramanian 2013). However, when mineral N was loaded on wood and sludge biochar surfaces, Keskinen et al (2021) reported no observable slow release effect. This finding is not surprising given that sorption and desorption of N on biochar surfaces is a rapid process often occurring on timescales of less than a day (Kizito et al 2015;Wang et al 2020).…”

Section: The Theory Of N-efficient Bcfsmentioning

confidence: 99%

Enhancing plant N uptake with biochar-based fertilizers: limitation of sorption and prospects

et al. 2022

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Background Biochar-based fertilizer products (BCF) have been reported to increase both crop yield and N-use efficiency. Such positive effects are often assumed to result from the slow-release of N adsorbed on BCF structures. However, a careful review of the literature suggests that actual mechanisms remain uncertain, which hampers the development of efficient BCF products. Scope Here, we aim at reviewing BCF mechanisms responsible for enhanced N uptake by plants, and evaluate the potential for further improvement. We review the capacity of biochar structures to adsorb and release N forms, the biochar properties supporting this effect, and the methods that have been proposed to enhance this effect. Conclusions Current biochar products show insufficient sorption capacity for the retention of N forms to support the production of slow-release BCFs of high enough N concentration. Substantial slow-release effects appear to require conventional coating technology. Sorption capacity can be improved through activation and additives, but currently not to the extent needed for concentrated BCFs. Positive effects of commercial BCFs containing small amount of biochar appear to result from pyrolysis-derived biostimulants. Our review highlights three prospects for improving N retention: 1) sorption of NH3 gas on specifically activated biochar, 2) synergies between biochar and clay porosities, which might provide economical sorption enhancement, and 3) physical loading of solid N forms within biochar. Beyond proof of concept, quantitative nutrient studies are needed to ascertain that potential future BCFs deliver expected effects on both slow-release and N use efficiency.

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Feasibility of Nitrogen-Enriched Chars as Circular Fertilizers

Cited by 9 publications

References 49 publications

Urea–Lignin/Chitosan Nanocomposite as Slow-Release Nanofertilizer

Urea–Lignin/Chitosan Nanocomposite as Slow-Release Nanofertilizer

End-of-life stage of renewable growing media with biochar versus spent peat or mineral wool

Enhancing plant N uptake with biochar-based fertilizers: limitation of sorption and prospects

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