Lignite reduces carbon and nitrogen loss from litter in commercial broiler housing.

The loss of carbon and nitrogen from broiler litter limits nutrient recycling and is damaging to the environment. This study investigated lignite, a low-rank brown coal, as an amendment to reduce the loss of carbon and nitrogen from broiler litter over 3 consecutive grow-out cycles, November 2021 to May 2022, at a commercially operated farm in Victoria, Australia. Lignite-treated litter contained significantly more carbon and nitrogen, with an increase of 70.1 g/bird and 12.6 g/bird for carbon and nitrogen, respectively. Lignite also reduced aerobic microbial respiration, with a 46.0% reduction in CO2 flux recorded in week 7 of the study, resulting in reduced mass loss. It is expected that this is a key mechanism responsible for nutrient retention in litter following treatment with lignite. Furthermore, lignite treatment lowered litter moisture content by 7, 6 and 3 percentage points for grow-out 1, 2 and 3, respectively. These findings present lignite as a beneficial litter amendment for increasing the nutrient value of waste and reducing carbon dioxide emissions. The study highlights the potential of lignite to reduce the environmental impact of poultry production and presents an alternative use for lignite as an existing resource.

NH3 and greenhouse gas emissions during co-composting of lignite and poultry wastes and the following amendment of co-composted products in soil.

Ammonia (NH3) and greenhouse gas (GHG) emissions are substantial contributors to C and N loss in composting. Lignite can increase N retention by absorbing NH4+ and NH3. However, the effects of co-composting on NH3 and GHG emissions in view of closing nutrient cycle are still poorly investigated. In the study, poultry litter was composted without (CK) or with lignite (T1) or dewatered lignite (T2), and their respective composts NH4+Com_CK, Com_T1, and Com_T2) were tested in a soil incubation to assess NH3 and GHG emission during composting and following soil utilization. The cumulative NH3 flux in T1 and T2 were reduced by 39.3% and 50.2%, while N2O emissions were increased by 7.5 and 15.6 times, relative to CK. The total GHG emission in T2 was reduced by 16.8% compared to CK. Lignite addition significantly increased nitrification and denitrification as evidenced by the increased abundances of amoA, amoB, nirK, and nirS. The increased reduction on NH3 emission by dewatered lignite could be attributed to reduced pH and enhanced cation exchangeable capacity than lignite. The increased N2O was related to enhanced nitrification and denitrification. In the soil incubation experiment, compost addition reduced NH3 emission by 72%∼83% while increased emissions of CO2 and N2O by 306%∼740% and 208%∼454%, compared with urea. Com_T2 strongly reduced NH3 and GHG emissions after soil amendment compared to Com_CK. Overall, dewatered lignite, as an effective additive, exhibits great potential to simultaneously mitigate NH3 and GHG secondary pollution during composting and subsequent utilization of manure composts.

Catalytic oxidation of lignite by Pt/TiO2 can enhance cadmium adsorption capacity.

Addressing global warming necessitates innovative strategies in fossil fuel management. This study evaluates lignite, a low-rank coal with limited calorific value, exploring applications beyond its use as fuel. Utilizing Pt/TiO2 catalytic oxidation, the research aims to enhance the cadmium adsorption capacity of lignite in wastewater. Lignite, treated with 0.5% Pt/TiO2 at 125 °C for 2 h, demonstrated a threefold increase in cadmium adsorption capacity. Characterization using TGA-DSC confirmed the modification process as exothermic and self-sustainable. Spectroscopic analysis and Boehm titration revealed significant alterations in pore structure, surface area, and oxygen-containing functional groups, emphasizing the effectiveness of catalytic oxidation. Adsorption mechanisms such as complexation, cation exchange, and cation-π interactions were identified, enhancing Cd adsorption. Techniques, including the d-band model, H2-TPR, and O2-TPD, indicated that dissociative adsorption of molecular O2 and the subsequent generation of reactive oxygen species introduced additional oxygen-containing functional groups on the lignite surface. These findings provide essential strategies for the alternative use of lignite in environmental remediation, promoting sustainable resource utilization and enhancing cost-effectiveness in remediation processes. ENVIRONMENTAL IMPLICATION: This study innovates in using lignite to reduce cadmium (Cd) contamination in wastewater. Employing Pt/TiO2 catalytic oxidation, lignite is transformed, enhancing its cadmium adsorption capacity. This process, being exothermic, contributes to decreased energy consumption. The approach not only mitigates the hazardous impacts of cadmium but also aligns with sustainability by reducing greenhouse gas emissions and energy use, showcasing a multifaceted environmental advancement.

Mini review: Targeting below-ground plant performance to improve nitrogen use efficiency (NUE) in barley.

Nitrogen (N) fertilizer is one of the major inputs for grain crops including barley and its usage is increasing globally. However, N use efficiency (NUE) is low in cereal crops, leading to higher production costs, unfulfilled grain yield potential and environmental hazards. N uptake is initiated from plant root tips but a very limited number of studies have been conducted on roots relevant to NUE specifically. In this review, we used barley, the fourth most important cereal crop, as the primary study plant to investigate this topic. We first highlighted the recent progress and study gaps in genetic analysis results, primarily, the genome-wide association study (GWAS) regarding both biological and statistical considerations. In addition, different factors contributing to NUE are discussed in terms of root morphological and anatomical traits, as well as physiological mechanisms such as N transporter activities and hormonal regulation.

Modified lignite and black coal reduce ammonia volatilization from cattle manure.

Modified lignite and black coal (BC) are potential amendments for animal bedding to abate ammonia (NH3) emissions due to their large adsorption capacities for ammoniacal nitrogen (N). However, the ability of modified lignite and BC in reducing NH3 volatilization from livestock manure and the underlying mechanisms remain unknown. The present study has investigated the effect of lignite, modified lignite, BC and modified BC on NH3 volatilization from cattle manure, biological immobilization of manure ammoniacal N and manure properties. Modified lignite and BC reduced the NH3 volatilization from manure by 44 and 36%, respectively, which were comparable with original lignite (43%). The biological immobilization of applied stable isotope labelled 15N in lignite, modified lignite, BC and modified BC amended manures was 15, 18, 11 and 16%, respectively, which were significantly higher than that in unamended manure (4%, P < 0.001). In addition, NH4+-N concentrations of lignite, modified lignite and modified BC amended manures (7.0-7.3 mg g-1) were significantly higher than that of the unamended and original BC amended manures (3.3 and 4.8 mg g-1, respectively, P < 0.001). However, the manure pH in all treatments remained alkaline (pH > 8.2). Our results highlight that the adsorption and immobilization of manure ammoniacal N induced by amendments are the key drivers in reducing NH3 loss from manure, outweighing the pH effect. The findings of this study provide new insights into the mechanisms of coal amendments reducing NH3 loss from animal manure and their potential applications in intensive livestock systems.

Lignite, dewatered lignite and modified subbituminous coal reduce nitrogen loss from broiler litter.

Broiler litter is generated in large quantities as a waste by-product of chicken meat production. N may be lost from the litter and emitted from bird housing as gaseous NH3, which can be damaging to the environment and limit the recycling of a valuable nutrient. This study investigated the effect of lignite application rate (0, 5, 10, 15, 20%) on N loss from broiler litter in a static chamber laboratory incubation. Lignite was subsequently dewatered and subbituminous coal modified by aerobic thermal oxidation and their ammoniacal N adsorption potentials were characterised. In a second static chamber incubation, the capacity of these materials (applied at 20%) to reduce N loss from litter was investigated. Finally, their potential to directly reduce NH3 emissions was examined using a chamber acid trap system. This study showed that lignite reduced N loss when applied to litter at a rate ≥ 5%, with the amount of N retained increasing with increasing lignite application rate. Litter treated with 20% lignite retained 24% more N than untreated litter. Following aerobic thermal treatment, maximum ammoniacal N adsorption capacities of the materials were as follows: lignite > dewatered lignite > modified subbituminous coal > subbituminous coal. Despite inequalities in adsorption capacity, lignite, dewatered lignite and modified subbituminous coal reduced total N loss by 17.3, 18.2 and 18.4% and NH3 emissions by 41.6, 49.1 and 29.8%, respectively. This study demonstrates the potential of coal-based materials to reduce NH3 emissions from broiler litter and increase the nutrient value of waste by reducing N loss.

Effects of Exotic Spartina alterniflora Invasion on Soil Phosphorus and Carbon Pools and Associated Soil Microbial Community Composition in Coastal Wetlands.

Soil microorganisms can be altered by plant invasion into wetland ecosystems and comprise an important linkage between phosphorus (P) availability and soil carbon (C) chemistry; however, the intrinsic mechanisms of P and C transformation associated with microbial community and function are poorly understood in coastal wetland. In this study, we used a sequential fractionation method and 13C nuclear magnetic resonance (NMR) spectroscopy to capture the changes in soil P pools and C chemical composition with bare flats (BF), native Phragmites australis(PA), and invasive Spartina alterniflora(SA), respectively. The responses of the soil microbial community using phospholipid fatty acid (PLFA) profiling and function indicated by nine enzyme activities associated with C, nitrogen (N), and P cycles were also investigated. Compared to PA and BF, SA invasion significantly (P < 0.05) changed P pools and mainly increased the available P by 17.5 and 37.0%, respectively. The presence of the plants (SA and PA) significantly (P < 0.05) altered the soil C chemical composition mainly by affecting the aliphatic functional groups, resulting in a lower alkyl C/O-alkyl C ratio value. Compared to BF and SA, PA significantly (P < 0.05) increased arbuscular mycorrhizal fungi (AMF) abundance. Soil enzyme activity, especially for the P and C cycle enzymes, was also affected by plant species with the highest geometric mean enzyme and hydrolase activity for the PA zone. We also found that soil C compositions and P pools were associated with microbial community structure and enzyme activity, respectively. However, little interaction between C and P was found on either soil microbial composition or soil enzyme activity variation. Further, microbial community composition was tightly correlated with the soil P compared to soil C chemistry, while enzyme activity showed more response with soil C chemistry compared to soil P pool changes.

Gas emissions during cattle manure composting and stockpiling.

Manure composting is a common management practice for cattle feedlots, but gaseous emissions from composting are poorly understood. The objective of this study was to quantify ammonia (NH3 ), nitrous oxide (N2 O), carbon dioxide (CO2 ), and methane (CH4 ) emissions from windrow composting (turning) and static stockpiling (nonturning) of manure at a commercial feedlot in Australia. An inverse-dispersion technique using an open-path Fourier transform infrared (OP-FTIR) spectrometer gas sensor was deployed to measure emissions of NH3 , N2 O, CO2 , and CH4 over a 165-d study period, and 29 and 15% of the total data intervals were actually used to calculate the fluxes for the windrow and stockpile, respectively. The nitrogen (N) lost as NH3 and N2 O emissions represented 26.4 and 3.8% of the initial N in windrow, and 5.3 and 0.8% of that in the stockpile, respectively. The carbon (C) lost as CO2 and CH4 emissions represented 44 and 0.3% of the initial C in windrow, and 54.8 and 0.7% of that in the stockpile, respectively. Total greenhouse gas (GHG) emissions from the manure windrow were 2.7 times higher than those of the stockpiled manure. This work highlights the value that could be accrued if one could reduce emissions of NH3 -N and N2 O-N from composting, which would retain manure N content while reducing GHG emissions.

Lignite as additives accelerates the removal of antibiotic resistance genes during poultry litter composting.

Antibiotic resistance genes (ARGs) in animal manure are a great threat to human health. This study investigated the effects of lignite addition at three levels (5%, 10%, 15% w/w) on the profiles of ARGs and the bacterial communities during poultry litter composting. Lignite addition effectively promoted the removal of manure-borne ARGs. After 65 days of composting, the relative abundances of ARGs decreased by 8.9% in control (no lignite), and by 15.8%, 27.7% and 41.5% in 5%, 10% and 15% lignite treatments, respectively. Although the total mobile genetic elements were enriched after composting, the enrichment of the intI-1 gene was significantly lower in the 10% and 15% lignite treatments compared with control. Network analysis indicated that Actinobacteria and Firmicutes were potential bacterial hosts for ARGs. Redundancy analysis showed that bacterial community succession played a key role in the shifts of ARGs. Taken together, this study provides evidence that lignite as additives promoted the removal efficacy of ARGs during composting of poultry litter.

An agricultural practise with climate and food security benefits: "Claying" with kaolinitic clay subsoil decreased soil carbon priming and mineralisation in sandy cropping soils.

As the agricultural sector seeks to feed a growing global population, climate-smart agriculture offers opportunities to concurrently mitigate climate change by reducing greenhouse gas emissions and/or increasing carbon storage in soils. This study examined the potential for clay addition to reduce CO2 emissions from plant residues and soil organic matter in a sandy soil. Soils were sourced from a 15-year-old field trial where claying (200 t ha-1) had already demonstrated improvements in water infiltration, grain yield and profits. Isotopically labelled plant residues (wheat, canola, or pea) were used to separate residue-derived and soil-derived CO2 sources from a nil-clay control, a historically clayed, and two freshly created soils with either high (10%) or low (3%) subsoil clay additions. Laboratory incubations demonstrated that historically clayed soils released less CO2 from plant residues and soil organic matter. Clay addition also decreased the priming effect of adding fresh residue to soils. The results from clay experimentally added in the laboratory varied. Differences in chemical and biological indicators (pH, microbial biomass C and N, extractable organic C and N, NO3-, NH4+, abundance of bacterial, archaeal, fungal, LMCO, GH48 and CbhI genes) did not correlate with patterns of CO2 emissions across treatments. While claying practices have previously demonstrated benefits to crop productivity, this research demonstrates long-term changes in carbon-cycling that could promote greater carbon sequestration.

Spectroscopic evidence for hyperthermophilic pretreatment intensifying humification during pig manure and rice straw composting.

Hyperthermophilic pretreatment composting (HPC) is superior to traditional composting (CK) with shortened maturity period and enhanced humification degree. However, the chemical and structural evolution of humic substances (HS) at the molecular level is not known. In this study, the impact of hyperthermophilic pretreatment (90 °C, 4 h) on the content and chemical composition of HS during composting were investigated. The HS content of the final compost was 87.8 g/kg and 76.7 g/kg in HPC and CK, respectively. Significantly higher humic acid/fulvic acid ratio (1.27 in HPC v.s. 0.77 in CK) was observed in HPC. 13C NMR spectroscopic data showed a higher aromatics percentage and earlier enrichment of aromatic structures in HS extracted from HPC than CK. Intensified humification of HPC was related to the increased levels of HS precursors and degradation of lignocellulose. Redundancy analysis demonstrated that aromatic C, phenolic C and O-alkyl C can be used for evaluation of the humification degree.

Long-term stabilization of crop residues and soil organic carbon affected by residue quality and initial soil pH.

Residues differing in quality and carbon (C) chemistry are presumed to contribute differently to soil pH change and long-term soil organic carbon (SOC) pools. This study examined the liming effect of different crop residues (canola, chickpea and wheat) down the soil profile (0-30cm) in two sandy soils differing in initial pH as well as the long-term stability of SOC at the amended layer (0-10cm) using mid-infrared (MIR) and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. A field column experiment was conducted for 48months. Chickpea- and canola-residue amendments increased soil pH at 0-10cm in the Podzol by up to 0.47 and 0.36units, and in the Cambisol by 0.31 and 0.18units, respectively, at 48months when compared with the non-residue-amended control. The decomposition of crop residues was greatly retarded in the Podzol with lower initial soil pH during the first 9months. The MIR-predicted particulate organic C (POC) acted as the major C sink for residue-derived C in the Podzol. In contrast, depletion of POC and recovery of residue C in MIR-predicted humic organic C (HOC) were detected in the Cambisol within 3months. Residue types showed little impact on total SOC and its chemical composition in the Cambisol at 48months, in contrast to the Podzol. The final HOC and resistant organic C (ROC) pools in the Podzol amended with canola and chickpea residues were about 25% lower than the control. This apparent priming effect might be related to the greater liming effect of these two residues in the Podzol.

Rhizosphere priming effect on soil organic carbon decomposition under plant species differing in soil acidification and root exudation.

Effects of rhizosphere properties on the rhizosphere priming effect (RPE) are unknown. This study aimed to link species variation in RPE with plant traits and rhizosphere properties. Four C3 species (chickpea, Cicer arietinum; field pea, Pisum sativum; wheat, Triticum aestivum; and white lupin, Lupinus albus) differing in soil acidification and root exudation, were grown in a C4 soil. The CO2 released from soil was trapped using a newly developed NaOH-trapping system. White lupin and wheat showed greater positive RPEs, in contrast to the negative RPE produced by chickpea. The greatest RPE of white lupin was in line with its capacity to release root exudates, whereas the negative RPE of chickpea was attributed to its great ability to acidify rhizosphere soil. The enhanced RPE of field pea at maturity might result from high nitrogen deposition and release of structural root carbon components following root senescence. Root biomass and length played a minor role in the species variation in RPE. Rhizosphere acidification was shown to be an important factor affecting the magnitude and direction of RPE. Future studies on RPE modelling and mechanistic understanding of the processes that regulate RPE should consider the effect of rhizosphere pH.

Free-air CO2 enrichment (FACE) reduces the inhibitory effect of soil nitrate on N2 fixation of Pisum sativum.

BACKGROUND AND AIMS: Additional carbohydrate supply resulting from enhanced photosynthesis under predicted future elevated CO2 is likely to increase symbiotic nitrogen (N) fixation in legumes. This study examined the interactive effects of atmospheric CO2 and nitrate (NO3(-)) concentration on the growth, nodulation and N fixation of field pea (Pisum sativum) in a semi-arid cropping system. METHODS: Field pea was grown for 15 weeks in a Vertosol containing 5, 25, 50 or 90 mg NO3(-)-N kg(-1) under either ambient CO2 (aCO2; 390 ppm) or elevated CO2 (eCO2; 550 ppm) using free-air CO2 enrichment (SoilFACE). KEY RESULTS: Under aCO2, field pea biomass was significantly lower at 5 mg NO3(-)-N kg(-1) than at 90 mg NO3(-)-N kg(-1) soil. However, increasing the soil N level significantly reduced nodulation of lateral roots but not the primary root, and nodules were significantly smaller, with 85% less nodule mass in the 90 NO3(-)-N kg(-1) than in the 5 mg NO3(-)-N kg(-1) treatment, highlighting the inhibitory effects of NO3(-). Field pea grown under eCO2 had greater biomass (approx. 30%) than those grown under aCO2, and was not affected by N level. Overall, the inhibitory effects of NO3(-) on nodulation and nodule mass appeared to be reduced under eCO2 compared with aCO2, although the effects of CO2 on root growth were not significant. CONCLUSIONS: Elevated CO2 alleviated the inhibitory effect of soil NO3(-) on nodulation and N2 fixation and is likely to lead to greater total N content of field pea growing under future elevated CO2 environments.