Substituting urea with biogas slurry and hydrothermal carbonization aqueous product could decrease NH3 volatilization and increase soil DOM in wheat growth cycle.

Biogas slurry (BS) and hydrothermal carbonization aqueous products (HAP), which are rich in nitrogen (N) and dissolved organic matter (DOM), can be used as organic fertilizer to substitute inorganic N fertilizer. To evaluate the effects of co-application of BS and HAP on the ammonia (NH3) volatilization and soil DOM content in wheat growth season, we compared six treatments that substituting 50%, 75%, and 100% of urea-N with BS plus HAP at low (L) or high (H) ratio, named BCL50, BCL75, BCL100, BCH50, BCH75, BCH100, respectively. Meanwhile, urea alone treatment was set as the control (CKU). The results showed that both BCL and BCH treatments significantly mitigate the NH3 volatilizations by 9.1%-45.6% in comparison with CKU (P < 0.05), whose effects were correlated with soil NH4+-N content. In addition, the decrease in soil urease activity contributed to the lower NH3 volatilization following application of BS plus HAP. Notably, BS plus HAP applications increased the microbial byproduct- and humic acid-like substances in soil by 9.9%-74.5% and 100.7%-451.9%, respectively. Consequently, BS and HAP amended treatments significantly increased soil humification index and DOM content by 13.7%-41.2% and 38.4%-158.7%, respectively (P < 0.05). This study suggested that BS and HAP could be co-applied into agricultural soil as a potential alternative of inorganic fertilizer N, which can decrease NH3 loss but increase soil fertility.

Chemical aging of hydrochar improves the Cd2+ adsorption capacity from aqueous solution.

Hydrochar (HC) serves as a promising adsorbent to remove the cadmium from aqueous solution due to porous structure. The chemical aging method is an efficient and easy-operated approach to improve the adsorption capacity of HC. In this study, four chemical aging hydrochars (CAHCs) were obtained by using nitric acid (HNO3) with mass fractions of 5% (N5-HC), 10% (N10-HC), and 15% (N15-HC) to age the pristine HC (N0-HC) and remove the Cd2+ from the aqueous solution. The results displayed that the N15-HC adsorption capacity was 19.99 mg g-1 (initial Cd2+ concentration was 50 mg L-1), which increased by 7.4 folds compared to N0-HC. After chemical aging, the specific surface area and oxygen-containing functional groups of CAHCs were increased, which contributed to combination with Cd2+ by physical adsorption and surface complexation. Moreover, ion exchange also occurred during the adsorption process of Cd2+. These findings have important implications for wastewater treatment to transform the forestry waste into a valuable adsorbent for Cd2+ removal from water.

Biowaste hydrothermal carbonization aqueous product application in rice paddy: Focus on rice growth and ammonia volatilization.

Hydrothermal carbonization (HTC) is known as a green biomass conversion technology. However, it often suffers from the issue of disposing hydrothermal carbonization aqueous products (HCAP). Based on the characterization and composition of acidic HCAP, a rice paddy soil column experiment was conducted to observe the effects of HCAP on ammonia (NH3) volatilization form paddy soil and rice yield. The experiment was designed with five treatments. HCAPs were produced at 220 °C and (SHC220-L) and 260 °C (SHC260-L) derived from poplar sawdust, HCAP produced at 220 °C (WHC220-L) and 260 °C (WHC260-L) derived from wheat straw, and a control group without HCAP application (termed CKU hereafter). The results showed that HCAP treatments increased the rice yield by 4.30%-26.0% compared to CKU. HACPs prepared at lower temperatures (SHC220-L and WHC220-L) mitigated the cumulative NH3 volatilization by 11.2% and 7.6%, respectively, and mitigated yield-scale NH3 volatilization (cumulative NH3 volatilization/total yield) by 14.2% âˆ¼ 22.4%. HCAP significantly improved the N use efficiency of rice. We found that the NH3 volatilization was related to NH4+-N concentration and pH of surface water, soil TOC and NH4+-N oxidation functional genes. This study implied that HCAP could be potentially used as a liquid fertilizer, which will be a potential substitute for chemical N fertilizers. There is still a long way before HCAP can be applied in full-scale for N fertilizer reduction and waste recycle.

The inhibiting effects of biochar-derived organic materials on rice production.

The effects of PBC and HBC on rice production, NUE and corresponding mechanisms were examined. Six treatments, P05, P30, H05, H30 (P: PBC; H: HBC; 05 and 30 represented the application rate of 0.5 and 3.0% w/w), CKU (urea application without char) and CK (no application of char and urea), were set up. Results showed that P05, P30 and H05 increased grain yield by 1.8-7.3% (P > 0.05), whereas H30 reduced grain yield by 60.4% (P < 0.05), compared to CKU. Meanwhile, HI under P05, P30 and H05 increased by 3.4-3.6%, while H30 decreased by 9.1% (P < 0.05). NUE and NAE showed similar trends with rice yield. By investigation, the excessive introduction of BDOM plays a crucial role in the reduction of rice production and NUE under higher HBC application. GC-MS/MS analysis showed that the soluble BDOM of HBC and PBC was quite different, and compounds such as 2,6-dimethoxyphenol might stress rice growth. ESI-FT-ICR-MS analysis showed that the BDOM of HBC contained a certain quantity of aromatic compounds, which may also stress rice growth. Overall, HBC pretreatment should be conducted, and the application rate should be strictly controlled before its agricultural application.

Clay-hydrochar composites mitigated CH4 and N2O emissions from paddy soil: A whole rice growth period investigation.

With the favorable microporous structure and excellent adsorption capacity, clay-hydrochar composites (CHCs) serve as promising materials to mitigate greenhouse gas emissions (GHG) from the paddy fields. Three clays were co-pyrolyzed with hydrochar derived from poplar sawdust to obtain CHCs, which were applied to the paddy fields to investigate the effects on methane (CH4) and nitrous oxide (N2O) emissions. Three CHCs were labeled as bentonite-hydrochar composite (BTHC), montmorillonite-hydrochar composite (MTHC), and kaolinite-hydrochar composite (KTHC), respectively. The effects of these three CHCs on GHG emissions were determined by monitoring the dynamic CH4 and N2O emissions in the paddy soil column ecosystem during the rice-growing season. The results showed that compared with the control group, three CHCs significantly mitigated CH4 and N2O emissions by 21.4%-47.5% and 5.2%-36.8%, respectively. Furthermore, the fluorescent components result displayed CHCs increased humic-like content by 29.62%-59.72%. A structural equation model was used to assess the hypothesis mitigation mechanism, which exemplified that GHG emissions negatively correlated with pmoA and nosZ genes, possibly resulting in the CH4 and N2O mitigation. Among the three CHCs, the KTHC amendment mitigated the CH4 and N2O emissions by 47.5% and 36.8%, respectively, which was superior to BTHC and MTHC. Hence, it was recommended for application to the field. Overall, this study demonstrates the mitigating effects of CHCs on GHG emissions for the first time, and the reduced CH4 and N2O emissions could contribute to increased soil C and N retention for better agricultural nutrients management.

Insights into the molecular transformation in the dissolved organic compounds of agro-waste-hydrochars by microbial-aging using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

Hydrochars-based dissolved organic matters (DOM) are easily available to organisms and thus have important influence on the biota once applying hydrochars as environment amendment. Thus, positive modifications on molecular composition of DOM is indispensable before hydrochars application. In this study, the impacts of microbial-aging by anaerobic fermentation on DOM of agro-waste-hydrochars was systematically assessed. Results revealed that microbial-aging caused lower DOM release but higher DOM molecular diversity. Moreover, microbial-aging resulted in the production of more biodegradable compounds, including lipids and proteins, and reduced the aromaticity of DOM. The highly oxygenated molecules (O/C > 0.6) were shifted into lower-order ones in the hydrochars-based DOM, suggesting the transformation of hydrophilic compounds into hydrophobic ones. Additionally, microbial-aging promoted the degradation of phenols by 99.0-98.9%, phenolic acids 37.8-73.5%, and polycyclic aromatic hydrocarbons by 83.4-90.4% in hydrochar-based DOM. Overall, this study demonstrates that microbial-aging changes the molecular characteristics of hydrochars-based DOM in a positive manner.

Effects of Gushukang for postmenopausal osteoporosis: A protocol for systematic review and meta-analysis.

BACKGROUND: Postmenopausal osteoporosis (PMO) is one of the most common systemic bone diseases with a high risk of fracture. Traditional herbal formula Gushukang (GSK) has been used to treat PMO. However, there is no systematic review related to GSK for PMO. The object of this work is to evaluate the efficacy and safety of GSK in the management of PMO. METHODS: We will search the PubMed, Embase, MEDLINE, Cochrane Library Central Register of Controlled Trials, China national knowledge infrastructure database (CNKI), Wan fang database, Chongqing VIP information, and SinoMed from their inception to May 2020. All randomized controlled trials (RCTs) of GSK for the treatment of PMO will be included. The improvement of vertebral fracture and bone mineral density (BMD) will be accepted as the primary outcomes. The meta-analyses will be performed by using the RevMan 5.3. RESULTS: This study will provide a high-quality comprehensive evaluation of the efficacy and safety of GSK for treating patients with PMO. CONCLUSION: The conclusion of our systematic review will provide evidence to judge whether GSK is an effective intervention for patients with PMO. TRIAL REGISTRATION NUMBER: 10.17605/OSF.IO/MKN3F.