The biotic effects of lignite on humic acid components conversion during chicken manure composting.

Targeted regulation of composting to convert organic matter into humic acid (HA) holds significant importance in compost quality. Owing to its low carbon content, chicken manure compost often requires carbon supplements to promote the humification progress. The addition of lignite can increase HA content through biotic pathways, however, its structure was not explored. The Parallel factor analysis revealed that lignite can significantly increase the complexity of highly humified components. The lignite addition improved phenol oxidase activity, particularly laccase, during the thermophilic and cooling phases. The abundance and transformation functions of core bacteria also indicated that lignite addition can influence the activity of microbial transformation of HA components. The structural equation model further confirmed that lignite addition had a direct and indirect impact on enhancing the complexity of HA components through core bacteria and phenol oxidase. Therefore, lignite addition can improve HA structure complexity during composting through biotic pathways.

Optimization of organic solid waste composting process through iron-related additives: A systematic review.

Composting is an environmentally friendly method that facilitates the biodegradation of organic solid waste, ultimately transforming it into stable end-products suitable for various applications. The element iron (Fe) exhibits flexibility in form and valence. The typical Fe-related additives include zero-valent-iron, iron oxides, ferric and ferrous ion salts, which can be targeted to drive composting process through different mechanisms and are of keen interest to academics. Therefore, this review integrated relevant literature from recent years to provide more comprehensive overview about the influence and mechanisms of various Fe-related additives on composting process, including organic components conversion, humus formation and sequestration, changes in biological factors, stability and safety of composting end-products. Meanwhile, it was recommended that further research be conducted on the deep action mechanisms, biochemical pathways, budget balance analysis, products stability and application during organic solid waste composting with Fe-related additives. This review provided guidance for the subsequent targeted application of Fe-related additives in compost, thereby facilitating cost reduction and promoting circular economy objectives.

The dominant role of cooperation in fungal community drives the humification process of chicken manure composting under addition of regulatory factors.

This study aimed to explore the action mechanism of fungal community on the enhancement of humification during chicken manure composting by regulating the core pathway of carbon metabolism - the tricarboxylic acid cycle. Regulators adenosine triphosphate (ATP) and malonic acid were added at the beginning of composting. The analysis of changes in humification parameters showed that the humification degree and stability of compost products were improved by adding regulators. Compared with CK, the humification parameters of adding regulators group increased by 10.98% on average. Meanwhile, adding regulators not only increased key nodes, but also strengthened the positive correlation between fungi, and network relationship was closer. Moreover, core fungi associated with humification parameters were identified by constructing OTU networks, and the division and cooperation mechanism of fungi were confirmed. Ultimately, the functional role of the fungal community acting on humification was confirmed by statistical means, that was, the fungal community promoting humification was the main group of composting process. And the contribution was more obvious in ATP treatment. This study was helpful to gain insight into the mechanism of regulators addition to advance the humification process, and provided new ideas for the safe, efficient and harmless disposal of organic solid waste.

Lignite drove phenol precursors to participate in the formation of humic acid during chicken manure composting.

This study set out to explore the impact of lignite on preserving organic matter and promoting the formation of humic acid (HA) during chicken manure composting. Composting test was carried out for control (CK), 5 % lignite addition treatment (L1), 10 % addition treatment (L2) and 15 % addition treatment (L3). The results demonstrated that lignite addition effectively reduced the loss of organic matter. The HA content of all lignite-added groups was higher than that of CK, and the highest was 45.44 %. L1 and L2 increased the richness of bacterial community. Network analysis showed higher diversity of HA-associated bacteria in L2 and L3 treatments. Structural equation models revealed that reducing sugar and amino acid contributed to the formation of HA during CK and L1 composting, while polyphenol contributed more to the HA formation during L2 and L3 composting. Furthermore, lignite addition also could promote the direct effect of microorganisms on HA formation. Therefore, the addition of lignite had practical significance to enhance compost quality.

Slowed down nitrogen mineralization under bacterial community-driven conditions by adding inhibitors during rice straw composting.

The aim of this paper was to confirm the role of inhibitors addition, namely adenosine triphosphate (ATP) and malonic acid (MA), on nitrogen availability during rice straw (RS) composting. The results showed that inhibitors addition slowed down the mineralization of ammonium nitrogen and nitrate nitrogen compared to CK. Meanwhile, amino sugar nitrogen and hydrolysable unknown nitrogen contents in ATP and MA treatments were higher, indicating that their addition improved the retention of organic nitrogen components. Furthermore, inhibitors additions attenuated the responsive relationship between bacterial communities and nitrogen components. The main reason was that the addition changed the bacterial community structure of RS compost. The final structural equation verified that inhibitors addition enhanced conversion between nitrogen components, that was, to complex nitrogen components to improve the quality of compost, and the remodeling of bacterial community played an important role. Therefore, adding inhibitors had a driving effect on promoting nitrogen sequestration.

Evaluating the phytotoxicity of dissolved organic matter derived from black carbon.

Dissolved organic matter (DOM) derived from black carbon (BC) can migrate from soil to river by rainfall or snow melting in nature. Because of the incomplete biomass combustion, BC produced at various temperatures is mixed, which is hard to divide the DOM at single temperature. Then it is difficult to explore the properties and risks of DOM in detail. Therefore, corn straws were selected to prepare BC under different heating temperature (200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C). Germination index combined the excitation-emission matrix-parallel factor (PARAFAC) and two-dimensional correlation spectra was employed to clarify the phytotoxicity and the PARAFAC components of DOM derived from BC at single temperature. Results showed that BC was hard to dissolve in water, but most of its DOM were toxic. Heating temperature promoted the formation of simple and complex fluorescent components. Combined with volume integration, it is the complex peaks of fluorescent components to determine the phytotoxicity of DOM derived from BC. These results would help to build a deep understanding of the fluorescence characteristics and toxicity of BC at different temperatures and emphasize the importance of reducing straw by burning.

The action difference of metabolic regulators on carbon conversion during different agricultural organic wastes composting.

The purpose of this study is to explore the action characteristics of metabolic regulators like adenosine tri-phosphate (ATP) and malonic acid (MA) during rice straw (RS) and fruit and vegetable waste (FVW) composting. Results showed that due to the easy degradation difference, ATP and MA reduced CO2 emission in RS and FVW, respectively. Moreover, adding ATP and MA increased humic acids (HA) content in FVW more significantly (p < 0.05), especially for ATP. However, adding MA accelerated organic matter degradation during RS composting, which was basically consistent with CO2 emission, but it was not effective in promoting HA formation. Furthermore, the microbial community was reshaped by adding ATP and MA. Eventually, structural equation model further confirmed that adding metabolic regulators enhanced the biotic and abiotic pathways of HA formation, and the promotion effect of adding ATP was more obvious. The study has great practical significance for the dispose of agricultural waste.

A comparison of lateral root patterning among dicot and monocot plants.

Lateral root branching along the primary root involves complex gene regulatory networks in model plant Arabidopsis. However, it is largely unclarified whether different plant species share a common mechanism to pattern the lateral root along the primary axis. In this study, we assessed the development pattern of lateral root among several dicot and monocot plants, including Arabidopsis, tomato, Medicago, Nicotiana, rice, and ryegrass by using an agar-gel culture system. Our results reveal a regular-spaced distribution pattern of lateral roots along the primary root axis of both dicot and monocot plants. Meanwhile, the root patterning is tightly controlled by root bending and the plant hormone auxin. However, nitrogen and phosphate starvations trigger distinguished root growth patterns among different plant species. Our studies strongly suggest a partially shared signaling pathway underlying root patterning of various plant species, and also provide a foundation for further identification of genes associated with root development.