Estimating thresholds of nitrogen, phosphorus and potassium fertilizer rates for rice cropping systems in China.

Determining the fertilization rate plays a pivotal role in agronomic practices as they directly impact yield targets, soil fertility, and environmental risks. In this study, we proposed a method that utilizes allowed ranges of partial nutrient balance and yield to estimate the threshold of nitrogen (N), phosphorus (P), and potassium (K) fertilizer applied to rice (Oryza sativa L.) fields in China. Based on a dataset of 6792 observations from rice fields, we determined the minimum and maximum rates of N, P and K suggested for single (mono-season rice), middle (summer-season rice rotated with winter-season upland crop), early and late (double-season rice cropping system) rice, ranging between 114-146 and 220-292 kg N ha-1 per season, 56-74 and 112-149 kg P2O5 ha-1 per season, and 170-230 and 329-347 kg K2O ha-1 per season, respectively. These values serve as the lower and upper fertilization thresholds, guiding yield goals and environmental protection. Furthermore, if rice straw is returned to fields, the demand for K fertilizer can theoretically decrease by 183 kg K2O ha-1, with corresponding decreases of 50 kg N ha-1 and 26 kg P2O5 ha-1, respectively. A recommended fertilization approach, excluding returned straw nutrients from the upper fertilization thresholds, suggested average application rates of 194 kg N ha-1, 105 kg P2O5 ha-1, and 157 kg K2O ha-1, which align well with the nutrient requirements of rice. Additionally, substituting organic N for chemical N is an effective approach to conserve chemical fertilizer N, potentially reducing chemical N usage by 20%-40%. Utilizing slow-release N is also a favorable option to enhance N use efficiency and optimize N balance. This study offers valuable insights into the development of fertilization restriction indicators, aiming to achieve a delicate balance between environmental impact and agricultural productivity through the adoption of balanced fertilization rates and utilization of organic residues.

Meta-analysis of GHG emissions stimulated by crop residue return in paddy fields: Strategies for mitigation.

The stimulating impact of crop residue return on greenhouse gas (GHG) emissions from paddy fields have been widely accepted, while the influence of site environmental and human factors on the simulating degree remains unclear. Here, we performed a meta-analysis to assess the GHG emissions affected by residue return, and its mitigation potential combined with key factors in paddy fields. Drawing upon 1047 observation sets of CH4 and N2O emissions from 155 peer-reviewed publications we found that residue return to paddy fields caused an average increase of 73% CH4 emissions and 14% in N2O emissions. Utilizing meta-analytical models, we identified pH as the most significant driver modulating GHG emissions, followed by soil organic matter (SOC) and total nitrogen. In alkaline soils, combining straw return with intermittent irrigation (285.2%) or mid-season drainage (118.9%) significantly reduced CH4 emissions compared to continuous flooding (1201.9%). Additionally, pairing straw return with higher nitrogen inputs (above 150 kg N ha-1) improved soil N2O uptake by -11.5%. In acid and neutral soils, straw carbonization achieved soil CH4 negative emissions (from -2.9% to -39.3%), but the long-term effects remained unclear. Reduced drainage frequency mitigates N2O emissions but may increase CH4 emissions. To efficiently mitigate GHG emissions, we proposed low-carbon schemes for acid or neutral soils based on specific SOC content: For soils with SOC content <10 g kg-1, prioritize nitrogen input control with rates not exceeding 174 kg N ha-1. For soils with SOC content >10 g kg-1, prioritize adjusting the type of straw. Our study underscores the significance of site-specific factors in modulating GHG emissions. Efficient GHG mitigation can be achieved by combining residue return with other agronomic measures tailored to different soil conditions.

Measurement of the effectiveness of Clonostachys rosea in reducing Fusarium biomass on wheat straw.

The survival and growth of plant pathogens on crop residues are key factors facilitating the dynamics of crop diseases. Spores (e.g., perithecia, and chlamydospores) and mycelium of pathogenic fungi overwinter on harvest residues, such as straw, and serve as initial inoculum infecting crops in the next growing season. Therefore, targeting overwintering fungi is essential to attaining effective disease control. Beneficial microorganisms offer advantages in controlling pathogens through their ability to colonize and exploit different environmental niches. In this study, we applied qPCR assays to explore the biocontrol performance of locally isolated strains of Clonostachys against various Fusarium pathogens. We proved that prior colonization of wheat straw by Fusarium spp. can be effectively reduced by Clonostachys rosea. We demonstrated that the efficiency of C. rosea to reduce Fusarium inoculum appears to remain at a similar level for most studied strains regardless of the target pathogen and the level of colonization of substrates by pathogens. Efficient performance of local C. rosea strains identifies possible targets for future strategies to control Fusarium diseases in cereals. Our study also highlights the challenge in sequence-based determination of C. rosea, which is crucial for the efficient selection of beneficial strains for biocontrol purposes.

Exploiting the Properties of Non-Wood Feedstocks to Produce Tailorable Lignin-Containing Cellulose Nanofibers.

Lignin-containing cellulose nanofibrils (LCNFs) are mainly produced commercially from treated wood pulp, which can decrease some of the carbon-negative benefits of utilizing biomass feedstock. In this work, LCNFs are prepared from non-wood feedstocks, including agricultural residues such as hemp, wheat straw, and flax. These feedstocks allowed for the preparation of LCNFs with a variety of properties, including tailored hydrophobicity. The feedstocks and their subsequent LCNFs are extensively characterized to determine the roles that feedstocks play on the morphology and properties of their resultant LCNFs. The LCNFs were then incorporated into paper handsheets to study their usefulness in papermaking applications, which indicated good potential for the use of wheat straw LCNFs as a surface additive to improve the oil resistance coating.

Biochar addition under straw return reduces carbon dioxide and nitrous oxide emissions in acidic tea field soil.

Straw return and biochar application are prevalent agricultural practices that bolster soil health, enhancing crop yields. However, their synergistic effects on carbon dioxide (CO2) and nitrous oxide (N2O) emissions in the acidic tea field soil at different age stages have not been fully elucidated. Herein, tea field soil with 5 and 15 years planting (5a and 15a, respectively) were individually incubated in five distinct indoor experiments: control, soil with urea (N), soil with urea and biochar (N + C), soil with urea and straw (N + S), and soil with urea, biochar, and straw (N + C + S). The results demonstrated that the pH values under 15a (4.1-5.6) were significantly lower than those under 5a (5.8-7.3), and both straw and biochar addition effectively improved soil acidification. Straw or biochar addition alone acted as carbon sources, leading to heightened N2O and CO2 emissions. N + S increased N2O emissions (3.17 and 5.85-fold) and CO2 cumulative emissions (6.43 and 2.33-fold) under 5a and 15a compared with the control. Relative to N treatment, biochar addition alone increased CO2 emission (1.22 and 1.35-fold) under 5a and 15a, and increased N2O emissions by 14.73% under 5a, decreased N2O emissions by 74.65% under 15a. However, the combined application of straw and biochar reduced N2O (49.4%,17.58%) and CO2 emissions (57.83% and 33.60%) due to stimulating biochar adsorption, respectively, compared with N + S treatment under 5a and 15a. Therefore, biochar and straw addition together can effectively increase soil fertilizer and inhibit greenhouse gas emissions, this study provides an insightful way and effective option for improving acid soil and protecting high soil health with a low greenhouse gas emission intensity.

Half substitution of mineral N with fish protein hydrolysate enhancing microbial residue C and N storage and climate benefits under high straw residue return.

The widespread utilization of straw return was a popular practice straw disposal for highly intensive agriculture in China, which has brought about some negative impacts such as less time for straw complete biodegradation, aggravation of greenhouse gas evolution, and lower efficient of carbon accumulation. It was urgent to find an eco-friendly N-rich organic fertilizer instead of mineral N as activator to solve the above problems and lead a carbon accumulation in long tern management. Besides, microbial necromass was considered as a crucial contributor to persistent soil carbon (C) and nitrogen (N) pool. How organic fertilizer activators influence microbial residue under different amount of crop residues input remained unclear. Thus, soils incorporating moderate and high rate of rice straw residue with additions of half and full of organic activators (fish protein hydrolysates vs. manure) were incubated for measuring carbon dioxide (CO2) and nitrous oxide (N2O) emission, microbial community and necromass. It was found that soil CO2 emission was rapidest during the first 13 days of straw decomposition but remained lowest in the treatments of 50% mineral N substituted by fish protein hydrolysate. There were that 81%-89% of total CO2 release and 59%-65% of total N2O emission occurred within 60 days of incubation period, and bacterial community and nitrate positively affected soil CO2 and N2O release respectively. Straw incorporation amount and organic activator application interactively influenced soil CO2 emission but not affected soil N2O emission. After 360 days of incubation, the difference of bacterial necromass was noticeable but fungal necromass remained almost unaltered across all treatments. All treatments showed generally comparable contribution of microbial necromass N to the total N pool. The treatment of 50% mineral N substituted by fish protein hydrolysate under high rate of straw input (HSF50) promoted the highest proportion of microbial necromass C in soil organic C because of alleviating N limitation for microorganisms. Finally, HSF50 was recommended as an eco-friendly strategy for enhancing microbial necromass C and N storage and climate benefits in agroecosystems.

Effect of straw decomposition on hexavalent chromium removal by straw: Significant roles of surface potential and dissolved organic matter.

Mobility and bioavailability of hexavalent chromium (Cr(VI)) in agricultural soils are affected by interactions between Cr(VI) and returned crop straws. However, the effect of straw decomposition on Cr(VI) removal and underlying mechanisms remain unclear. In this study, Cr(VI) removal by pristine and decomposed rice/rape straws was investigated by batch experiments and a series of spectroscopies. The results showed that straw decomposition inhibited Cr(VI) removal, regardless of straw types. However, the potential mechanisms of the inhibition were distinct for the two straws. For the rice straw, a lower zeta potential after decomposition suppressed Cr(VI) sorption and subsequent reduction. In addition, less Cr(VI) was reduced by the decomposed rice straw-derived dissolved organic matter (DOM) than the pristine one. In contrast, for the rape straw, due to the increased zeta potential after decomposition, the decreased Cr(VI) removal was mainly ascribed to less Cr(VI) reduction by the rape straw-derived DOM. These results emphasized the significant roles of straw surface potential and DOM in Cr(VI) removal, depending on straw types and decomposition, which facilitate the fundamental understanding of Cr(VI) removal by straws and are helpful for predicting the environmental risk of Cr and rational straw return in Cr(VI)-contaminated fields.

Rice straw waste-based green synthesis and characterizations investigation of Fe-MoS2-derived nanohybrid.

In present work, synthesis of a nanohybrid material using Fe and MoS2 has been performed via a cost-effective and environmentally friendly route for sustainable manufacturing innovation. Rice straw extract was prepared and used as a reducing and chelating agent to synthesize the nanohybrid material by mixing it with molybdenum disulfide (MoS2) and ferric nitrate [Fe (NO3)3.9H2O], followed by heating and calcination. The X-ray diffraction (XRD) pattern confirms the formation of a nanohybrid consisting of monoclinic Fe2(MoO4)3, cubic Fe2.957O4, and orthorhombic FeS with 86% consisting of Fe2(MoO4)3. The properties were analyzed through Fourier-transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results of the dynamic light scattering (DLS) study revealed a heterogeneous size distribution, with an average particle size of 48.42 nm for 18% of particles and 384.54 nm for 82% of particles. Additionally, the zeta potential was measured to be -18.88 mV, suggesting moderate stability. X-ray photoelectron spectroscopy (XPS) results confirmed the presence of both Fe2+ and Fe3+ oxidation states along with the presence of Molybdenum (Mo), oxygen (O), and Sulphur (S). The prepared nanohybrid material exhibited a band gap of 2.95 eV, and the photoluminescence intensity increased almost twice that of bare MoS2. The present work holds potential applications in photo luminescent nanoplatform for biomedical applications.

Seasonal Variability of Lipophilic Compounds in Oat (Avena sativa L.) Straw: A Comprehensive Chemical Study.

Oat straw, a residue of Avena sativa L., is recognized for its abundance in cellulose, hemicelluloses, and lignin. However, its potential as a source of lipophilic compounds within the framework of a biorefinery concept still remains unexplored. In this study, we conducted an extensive investigation into the content and chemical composition of the lipophilic compounds present in acetone extracts from oat straws of two distinct oat varieties, namely, Karen and Isaura. Furthermore, we examined their seasonal variability in content and composition in straw samples from oats planted in both spring and winter seasons. The extracted lipophilic compounds were predominantly composed of high molecular weight esters (26.0-38.1%), steroids (16.6-24.0%), n-fatty alcohols (10.9-20.7%), n-fatty acids (10.9-16.0%), and n-aldehydes (10.7-15.8%), with lower amounts of n-alkanes (1.1-3.0%), acylglycerides (2.3-3.8%), phytol and phytyl esters (0.6-2.9%), ß-diketones (0.1-2.5%), triterpenoids (0.9-1.2%), tocopherols and tocopheryl esters (0.2-0.7%), 2-hydroxy fatty acids (0.1-0.2%), and n-alkylresorcinols (0.1%). Notably, these different classes of compounds exhibited variations in their contents depending on the oat variety and the specific planting season. Of particular interest was the Karen variety, which presented significant amounts of high molecular weight esters, free fatty acids, and acylglycerols, especially when it was cultivated during the winter season. These findings underline the potential of oat straw as a valuable resource for lipid extraction within a biorefinery context and emphasize the importance of selecting the appropriate variety and season for optimal lipid yield.

Tailoring the structural and physicochemical properties of rice straw cellulose-based cryogels by cell-mediated polyhydroxyalkanoate deposition.

This study presents a novel biotechnological approach for creating water vapor-resistant cryogels with improved integrity. Rice straw cellulose was transformed into nanofibrils through TEMPO-mediated oxidation and high-pressure homogenization. The resulting cryogels remained firm even when immersed in aqueous media, whose pores were used by live cell to deposit polyhydroxyalkanoate (PHA) particles inside them. This novel method allowed the compatibilization of PHA within the cellulosic fibers. As a consequence, the water sorption capacity was decreased by up to 6 times having just 4 % of PHA compared to untreated cryogels, preserving the cryogel density and elasticity. Additionally, this technique can be adapted to various bacterial strains and PHA types, allowing for further optimization. It was demonstrated that the amount and type of PHA (medium chain length and small chain length-PHA) used affects the properties for the cryogels, especially the water vapor sorption behavior and the compressive strength. Compared to traditional coating methods, this cell-mediated approach not only allows to distribute PHA on the surface of the cryogel, but also ensures polymer penetration throughout the cryogel due to bacterial self-movement. This study opens doors for creating cryogels with tunable water vapor sorption and other additional functionalities through the use of specialized PHA variants.

Effect of alkali treatment on mechanical and water absorption properties of biodegradable wheat-straw/glass fiber reinforced epoxy hybrid composites: A sustainable alternative for conventional materials.

Fiber-reinforced polymer composites are preferred over conventional materials because of their superior strength and modulus. Previously limited due to high manufacturing costs, synthetic fibers have been replaced by some natural fibers, such as waste wheat straw fibers. Here, epoxy-based polymer composites' mechanical and physical properties have been investigated, focusing on fiber weight ratios for both treated and untreated fiber. The research found that treated fibers display more effective mechanical qualities than untreated fibers, with a higher tensile strength of 54.4 MPa. The untreated Wheat Straw-Glass fiber reinforced composite has a less tensile strength of 26.3 MPa (10 wt% fiber). Pure resin-based composite has the most minor tensile strength at 1.52 MPa. The highest flexural strength obtained for hybrid composite is 88.76 MPa for treated fiber with epoxy resin and 49.6 MPa for untreated 30 wt % fiber. At the same time, the sole epoxy resin composite has the lowest value of 10.60 MPa. Untreated fiber (30 wt%) has the highest impact energy of 8J. Untreated wheat straw fiber absorbs more water due to its hydrophilic nature. In contrast, treated fiber exhibits better bonding and minimal water content, and the sole epoxy resin composite exhibits hydrophobic properties, resulting in less water absorption. The treated fiber displays better bonding than the untreated fiber throughout the SEM analysis. Wheat Straw fiber is mainly used for biodegradable plastic formation, housing construction, building materials, etc.

Preparation of straw/PLA composites with excellent flame retardancy based on deep eutectic solvent sulfonation.

There have been numerous studies on flame retardant modification of natural fiber/PLA composite materials due to the demand for applications. However, the existing flame retardant modification methods mostly involve adding flame retardants, which have a negative impact on the mechanical properties. Based on this, this study aims to introduce sulfonic groups into the cellulose of straw fibers via modification with a sulfamic acid-based deep eutectic solvent (SDES), thereby achieving flame retardance without affecting the inherent mechanical properties of the composite material. The performance enhancement of DS/PLA is manifested in the following specific aspects: the LOI reaches 36.53 %, the thermal stability is improved from 7.8 % of the residual carbon of PS/PLA to 38.4 %, and the tensile modulus is increased by 69.5 %. The preparation scheme for straw/PLA composite materials in this study is simple, economical, and efficient, and the flame retardant performance of the composite material is excellent, providing valuable references for flame retardant modification of natural fiber/plastic composite materials.

Critical assessment of furrow openers and operational parameters for optimum performance under conservation tillage.

Conservation Agriculture (CA) is an innovative approach that promotes sustainable farming while enhancing soil health. However, residue management challenges often hinder its adoption, causing farmers to burn crop leftovers in fields. This study aimed to evaluate the effectiveness of various furrow openers under simulated soil bin conditions. Three types of furrow openers were examined: single disk (SD), Inverted T-type furrow opener with a plain rolling coulter (ITRC), and double disc (DD) furrow opener. Tests were conducted at different forward speeds (1.5, 2, and 2.5 km h-1) and with three straw densities (1, 2, and 3 t ha-1) at a consistent working depth of 5 cm. Draft measurements were obtained using load cells connected to an Arduino-based data-logging system. Results indicated that draft requirements increased with forward speed and straw density, while straw-cutting efficiency decreased with these factors. Average draft values for SD, ITRC, and DD were 290.3 N, 420 N, and 368.5 N, respectively, and straw-cutting efficiencies were 53.62%, 59.47%, and 74.89%, respectively. The DD furrow opener showed the highest straw-cutting efficiency (81.36%) at a working speed of 1.5 km h-1 and a straw density of 1 t ha-1, demonstrating optimal performance compared to other furrow openers.

Long-Term Straw Returning Enhances Phosphorus Uptake by Zea mays L. through Mediating Microbial Biomass Phosphorus Turnover and Root Functional Traits.

The intensive use of chemical fertilizers in China to maintain high crop yields has led to significant environmental degradation and destabilized crop production. Returning straw to soil presents a potential alternative to reduce chemical fertilizer requirements and enhance soil fertility. This study investigates the effects of different nitrogen (N) input levels and straw additions on crop phosphorus (P) uptake and soil P availability based on a long-term N-fertilizer trial. The treatments included no fertilizer input (CK), conventional (NPK), reduced NPK (0.75NPK), and straw-amended (SNPK) treatments. Results indicate that SNPK significantly enhances shoot P uptake and crop yields by 43.7-61.9% and 29.3-39.6%, respectively. The SNPK treatment improved rhizosphere P availability and increased the phosphorus activation coefficient (PAC) by 1.72-fold compared to NPK alone. The enhanced soil P availability under SNPK was primarily attributed to an abundance of functional microbes, leading to higher P storage in the microbial biomass P pool and its turnover. Additionally, SNPK promoted root exudate and phosphate-mobilizing microbes, enhancing P mobilization and uptake. Nitrogen fertilization primarily influenced root functional traits related to P acquisition. These findings provide valuable insights for developing effective fertilizer management strategies in maize-oilseed rape rotation systems, emphasizing the benefits of integrating straw with chemical fertilizers.

Successive Years of Rice Straw Return Increased the Rice Yield and Soil Nutrients While Decreasing the Greenhouse Gas Intensity.

Straw return has important impacts on black soil protection, food security, and environmental protection. One year of straw return (S1) reduces rice yield and increases greenhouse gas (GHG) emissions. However, the effects of successive years of straw return on rice yield, soil nutrients, and GHG emissions in the northeast rice region are still unclear. Therefore, we conducted four successive years of straw return (S4) in a positional experiment to investigate the effects of different years of straw return on rice yield, soil nutrients, and GHG emissions in the northeast rice region. The experimental treatments included the following: no straw return (S0), a year of straw return (S1), two successive years of straw return (S2), three successive years of straw return (S3), and four successive years of straw return (S4). Compared with S1, the rice yields of S2, S3, and S4 increased by 10.89%, 15.46%, and 16.98%, respectively. But only S4 increased by 4.64% compared to S0, while other treatments were lower than S0. S4 increased panicles per m2 and spikelets per panicle by 9.34% and 8.93%, respectively, compared to S1. Panicles per m2 decreased by 8.06% at S4 compared to S0, while spikelets per panicle increased by 13.23%. Compared with S0, the soil organic carbon, total nitrogen, NH4+-N, NO3--N, available phosphorus, and available potassium of S4 increased by 11.68%, 10.15%, 24.62%, 21.38%, 12.33%, and 13.35%, respectively. Successive years of rice straw return decreased GHG intensity (GHGI). Compared with S1, the GHGI of S4, S3, and S2 decreased by 16.2%, 11.84%, and 9.36%, respectively. Thus, S4 increased rice yield and soil nutrients, reducing GHGI.

Effects of Different Straw Return Modes on Soil Carbon, Nitrogen, and Greenhouse Gas Emissions in the Semiarid Maize Field.

Returning straw to the field is a crucial practice for enhancing soil quality and increasing efficient use of secondary crop products. However, maize straw has a higher carbon-to-nitrogen ratio compared to other crops. This can result in crop nitrogen loss when the straw is returned to the field. Therefore, it is crucial to explore how different methods of straw return affect maize (Zea mays L.) farmland. In this study, a field experiment was performed with three treatments (I, no straw returned, CK; II, direct straw return, SR; and III, straw returned in deep furrows, ISR) to explore the effects of the different straw return modes on soil carbon and nitrogen content and greenhouse gas emissions. The results indicated that the SR and ISR treatments increased the dissolved organic carbon (DOC) content in the topsoil (0-15 cm). Additionally, the ISR treatment boosted the contents of total nitrogen (TN), nitrate nitrogen (NO3--N), ammonium nitrogen (NH4+-N), dissolved organic nitrogen (DON), and DOC in the subsurface soil (15-30 cm) compared with CK. When it comes to greenhouse gas emissions, the ISR treatment led to an increase in CO2 emissions. However, SR and ISR reduced N2O emissions, with ISR showing a more pronounced reduction. The ISR treatment significantly increased leaf and grain biomass compared to CK and SR. The correlation analyses showed that the yield was positively correlated with soil DOC, and soil greenhouse gas emission was correlated with soil NO3--N. The ISR technology has great potential in sequestering soil organic matter, improving soil fertility, and realizing sustainable agricultural development.

Straw Tar Epoxy Resin for Carbon Fiber-Reinforced Plastic: A Review.

The massive consumption of fossil fuels has led to the serious accumulation of carbon dioxide gas in the atmosphere and global warming. Bioconversion technologies that utilize biomass resources to produce chemical products are becoming widely accepted and highly recognized. The world is heavily dependent on petroleum-based products, which may raise serious concerns about future environmental security. Most commercially available epoxy resins (EPs) are synthesized by the condensation of bisphenol A (BPA), which not only affects the human endocrine system and metabolism, but is also costly to produce and environmentally polluting. In some cases, straw tar-based epoxy resins have been recognized as potential alternatives to bisphenol A-based epoxy resins, and are receiving increasing attention due to their important role in overcoming the above problems. Using straw tar and lignin as the main raw materials, phenol derivatives were extracted from the middle tar instead of bisphenol A. Bio-based epoxy resins were prepared by replacing epichlorohydrin with epoxylated lignin to press carbon fiber sheets, which is a kind of bio-based fine chemical product. This paper reviews the research progress of bio-based materials such as lignin modification, straw pyrolysis, lignin epoxidation, phenol derivative extraction, and synthesis of epoxy resin. It improves the performance of carbon fiber-reinforced plastic (CFRP) while taking into account the ecological and environmental protection, so that the epoxy resin is developed in the direction of non-toxic, harmless and high-performance characteristics, and it also provides a new idea for the development of bio-based carbon fibers.

Synergistic treatment of digested wastewater with high ammonia nitrogen concentration using straw and microalgae.

Microalgae as a promising approach for wastewater treatment, has challenges in directly treating digested piggery wastewater (DPW) with high ammonia nitrogen (NH4+-N) concentration. To improve the performance of microalgae in DPW treatment, straw was employed as a substrate to form a straw-microalgae biofilm. The results demonstrated that the straw-microalgae biofilm achieved the highest NH4+-N removal rate of 193.2 mg L-1 d-1, which was 28.8 % higher than that of culture system without straw. The final NH4+-N concentration in the effluent met the discharge standard of 5 mg L-1. Furthermore, the total organic carbon (TOC) released from straw facilitated bacterial proliferation and the secretion of extracellular polymeric substances (EPS). The EPS and TOC increased the suspension viscosity and surface tension, thereby enhancing the residence time of CO2 in the liquid phase and promoting CO2 fixation. This study presented a novel method for the biological treatment of high-ammonia-nitrogen DPW.

PBAT biodegradable microplastics enhanced organic matter decomposition capacity and CO2 emission in soils with and without straw residue.

Recent studies show that biodegradable microplastics (BMPs) could increase soil CO2 emission, but whether altered carbon emission results from modified soil organic matter (SOM) decomposition remains underexplored. In this study, the effect and mechanisms of BMPs on CO2 emission from soil were investigated, using poly(butylene adipate-co-terephthalate) (PBAT, the main component of agricultural film) as an example. Considering that straw returning is a common agronomic measure which may interact with microplastics through affecting microbial activity, both soils with and without wheat straw were included. After 120 d, 1 % (w/w) PBAT BMPs ificantly increased cumulative CO2 emission by 1605.6 and 1827.7 mg C kg-1 in soils without and with straw, respectively. Cracks occurred on the surface of microplastics, indicating that CO2 was partly originated from plastic degradation. Soil dissolved organic matter (DOM) content, carbon degradation gene abundance (such as abfA, xylA and manB for hemicellulose, mnp, glx and lig for lignin, and chiA for chitin) and enzyme activities increased, which significantly positively correlated with CO2 emission rate (p < 0.05), suggesting that PBAT enhanced carbon emission by stimulating the decomposition of SOM (and possibly the newly added straw) via co-metabolism and nitrogen mining. This is supported by DOM molecular composition analysis which also demonstrated stimulated turnover of carbohydrates, amino sugars and lignin following PBAT addition. The findings highlight the potential of BMPs to affect SOM stability and carbon emission.

Deep eutectic solvent and molten salt-assisted construction of wheat straw-derived N/O co-doped porous carbon for flexible zinc-air batteries.

As a common biomass resource, wheat straw is gradually being derived as carbon materials for oxygen reduction reaction (ORR) in zinc-air batteries (ZABs). Herein, the wheat straw-derived carbon was prepared by ball milling and pyrolysis using deep eutectic solvent (DES) as the medium, which avoided the cumbersome procedures. The hydrogen bond of DES was utilized to reconstructed into a hydrogen bond network structure between DES and lignin/cellulose/hemicellulose of wheat straw. The hydrogen bond network structure was converted into N/O co-doped porous carbon (N/O-WSPC) with abundant N/O co-doped sites after high-temperature pyrolysis. Meanwhile, KHCO3 was employed to further generate hierarchical pore structures and increase the specific surface area of the N/O-WSPC. The N/O co-doped sites provided intrinsic ORR activity, while the porous structure facilitates the mass transfer effect. Therefore, the N/O-WSPC exhibited a half-wave potential of 0.87 V (vs. RHE) and a limiting current density of 5.98 mA cm-2 for ORR.The N/O-WSPC-based flexible ZAB displayed an energy density of 652.23 Wh kg-1 and a charging-discharging cycle duration for over 19 h. The DES-assisted strategy facilitates the sustainable and efficient application of wheat straw-derived carbon materials in energy storage and conversion devices.