Qiang Xiao

Globally, intensive crop production increasingly relies on precise regulation of water, nutrients, and the root-zone environment, while prolonged agrochemical use, soil degradation, salinization, a...

Improving nitrogen fertilizer use efficiency while reducing nitrogen losses is a major challenge for sustainable crop production. In this study, a controlled-release inhibitor-enhanced nitrogen fertilizer (CYRF) was developed by integrating a polyurethane controlled-release membrane with a 3,4-dimethylpyrazole phosphate (DMPP) nitrification-inhibitor layer. Its structural characteristics, nutrient release behavior, and nitrogen-regulating performance were evaluated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, static water incubation, soil incubation at different temperatures and field nitrogen-15 (¹⁵N) tracing. Morphological and elemental analyses confirmed that CYRF possessed a distinct multilayer structure consisting of an outer controlled-release membrane and an inner DMPP-containing inhibitor layer, providing a structural basis for the coordinated release of urea nitrogen and DMPP. Under static water incubation at 25 °C, the cumulative release of urea nitrogen increased from 0.40% at 7 d to 87.50% at 98 d, while DMPP release increased from 0.70% to 79.00% over the same period. DMPP was released slightly earlier than urea nitrogen during the 21–49 d incubation period, and their cumulative release rates were strongly positively correlated (r = 0.975, P < 0.001). Soil incubation showed that CYRF consistently enhanced ammonium nitrogen retention while suppressing nitrate nitrogen accumulation across different temperatures. Compared with the controlled-release fertilizer (CRF), CYRF increased ammonium nitrogen retention by 37.3% and reduced nitrate nitrogen accumulation by 16.4% at 15 °C. At 25 °C, CYRF reduced nitrate nitrogen accumulation by 97.0–98.7% during the 50–90 d incubation period, while at 35 °C it decreased nitrate nitrogen accumulation by 42.0%. Field ¹⁵N tracing further showed that, compared with CRF( ¹⁵ N), CYRF( ¹⁵ N) significantly increased ¹⁵ N utilization rates by 14.60 and 5.30 percentage points and reduced nitrogen loss rates by 11.45 and 11.11 percentage points in winter wheat and summer maize, respectively. Overall, CYRF effectively synchronized controlled nitrogen release with nitrification inhibition, providing a promising strategy for improving nitrogen use efficiency and reducing nitrogen losses in agricultural production.

Developing functional agricultural materials that synchronize nutrient release, water retention, and soil amendment is crucial to advancing resource-efficient, sustainable farming systems. However, integrating these multifunctional properties within a single material remains a significant challenge. In this work, we fabricated a multifunctional hydrogel (CPAUH) via a one-pot synthesis strategy, which was composed of carboxylated cellulose nanofibers as a rigid network combined with poly(AA-co-KAA), forming a semi-interpenetrating network (semi-IPN) for loading urea and humic acid. The structure and properties of hydrogels were characterized by FTIR, TGA, SEM, and XPS. The CPAUH exhibited outstanding mechanical strength (0.169 MPa), water absorption capacity (121.65 g g⁻¹), and retained 118 g g⁻¹ after three absorption–desorption cycles, demonstrating remarkable structural stability. Nutrient release kinetics revealed sustained-release behavior, with cumulative elution of only 66.91% for urea and 92.45% for humic acid over 15 days. Under salt stress, the 1.5% CPAUH amendment (P2) markedly enhanced wheat growth compared with the non-amended control (P0), as reflected by significant increases in plant height, chlorophyll content, fresh weight, dry weight, and nitrogen uptake. Concurrently, CPAUH application effectively improved soil conditions by reducing electrical conductivity by 39.16% (to 4.38 mS·cm⁻¹). These collective findings of CPAUH hydrogel offer substantial potential as a multifunctional soil amendment for enhancing water-fertilizer efficiency, reclaiming saline–alkali soils, and improving crop productivity under resource-limited conditions.

Developing sustainable and high-performance sorbents for efficient CO₂ capture is essential for mitigating climate change and reducing industrial emissions. In this study, phosphorus-doped porous carbons (LPSP-T) were synthesized via a one-step activation–doping strategy using lotus petiole biomass as a precursor and sodium phytate as a dual-function activating and phosphorus-doping agent. The simultaneous activation and phosphorus incorporation at various temperatures (650–850 °C) under a nitrogen atmosphere produced carbons with tailored textural properties and surface functionalities. Among them, LPSP-700 exhibited the highest specific surface area (525 m²/g) and a hierarchical porous structure, with abundant narrow micropores (2 capture performance. The introduction of P functionalities not only improved the surface polarity and binding affinity toward CO₂ but also promoted the formation of a well-connected pore network. As a result, LPSP-700 delivered a CO₂ uptake of 2.51 mmol/g at 25 °C and 1 bar (3.34 mmol/g at 0 °C), along with a high CO₂/N₂ selectivity, fast CO₂ adsorption kinetics and moderate isosteric heat of adsorption (Q_st). Furthermore, the dynamic CO₂ adsorption capacity (0.81 mmol/g) was validated by breakthrough experiments, and cyclic adsorption–desorption tests revealed excellent stability with negligible loss in performance over five cycles. Correlation analysis revealed pores < 2.02 nm as the dominant contributors to CO₂ uptake. Overall, this work highlights sodium phytate as an effective dual-role agent for simultaneous activation and phosphorus doping and validates LPSP-700 as a sustainable and high-performance sorbent for CO₂ capture under post-combustion conditions.

The CO₂ capture from flue gas using biomass-derived porous carbons presents an environmentally friendly and sustainable strategy for mitigating carbon emissions. However, the conventional fabrication of porous carbons often relies on highly corrosive activating agents like KOH and ZnCl₂, posing environmental and safety concerns. To address this challenge, in the present work sodium metaborate tetrahydrate (NaBO₂·4H₂O) has been utilized as an alternative, eco-friendly activating agent for the first time. Moreover, a water chestnut shell (WCS) is used as a sustainable precursor for boron-doped porous carbons with varied microporosity and boron concentration. It was found out that pyrolysis temperature significantly determines the textural features, elemental composition, and CO₂ adsorption capacity. With a narrow micropore volume of 0.27 cm³/g and a boron concentration of 0.79 at.% the representative adsorbent presents the maximum CO₂ adsorption (2.51 mmol/g at 25 °C, 1 bar) and a CO₂/N₂ selectivity of 18 in a 10:90 (v/v) ratio. Last but not least, the as-prepared B-doped carbon adsorbent possesses a remarkable cyclic stability over five cycles, fast kinetics (95% equilibrium in 6.5 min), a modest isosteric heat of adsorption (22–39 kJ/mol), and a dynamic capacity of 0.80 mmol/g under simulated flue gas conditions. This study serves as a valuable reference for the fabrication of B-doped carbons using an environmentally benign activating agent for CO₂ adsorption application.

CO₂ capture from the flue gas is a promising approach to mitigate global warming. However, regulating the carbon-based adsorbent in terms of textural and surface modification is still a challenge. To overcome this issue, the present study depicts the development of cost-effective and high-performance CO₂ adsorbents derived from petroleum coke, an industrial by-product, using a two-step process involving thiourea modification and KOH activation. A series of N,S-codoped porous carbons was synthesized by varying activation temperatures and KOH quantity. The optimized sample exhibited a high specific surface area of 1088 m²/g, a narrow micropore volume of 0.52 cm³/g, and considerable heteroatom doping (1.57 at.% nitrogen and 0.19 at.% sulfur). The as-prepared adsorbent achieved a CO₂ adsorption capacity of 3.69 and 5.08 mmol/g at 1 bar, 25 °C and 0 °C, respectively, along with a CO₂/N₂ selectivity of 17. Adsorption kinetics showed 90% of equilibrium uptake was achieved within 5 min, while cyclic studies revealed excellent stability with 97% capacity retention after five cycles. Thermodynamic analysis indicated moderate isosteric heat of adsorption (Q_st) values ranging from 18 to 47 kJ/mol, ensuring both strong adsorption and efficient desorption. These findings highlight the potential of petroleum coke-derived porous carbons for sustainable and efficient CO₂ capture applications.

To identify the general pattern of impact of the application of the mixed controlled-release urea (CRU) with urea (C-U) on grain yield, plant characteristics, NUE and soil nitrogen contents in wheat–maize production, a 5-year field trial with three release longevity and four ratios of CRU in C-U and common urea alone (U) was carried out in the North China Plain. Results with meta-analysis revealed that C-U had significant effects on grain yield and plant characteristics, NUE and soil NO₃⁻-N contents in wheat–maize production positively with the release longevity of CRU and the ratio of CRU-N in C-U. The application of C-U with 60 d or 90 d CRU for wheat and maize had the best overall effects, while C-U treatment with 30 d CRU had a significant inhibitory effect. For maize, C-U with 30% CRU-N had the largest increase rate on yield, 1000-grain weight, plant height, dry weight and NUE by 5.13%, 1.61%, 3.70%, 11.33%, and 8.63%, respectively, while C-U with 40% CRU-N had the largest reduction soil NO₃⁻-N. For wheat, the application of C-U with 40% CRU-N had a significant effect on yield, sterile spikelet number, and NUE by 4.45%, −9.76%, and −8.04%, respectively. To conclude, the use of the C-U with appropriate release longevity and the ratio of CRU has great potential to proliferate wheat–maize yields and reduce fertilizer loss especially for maize that not only provides an effective generic methodology for agriculture to improve measures but also ensures profitability.

Nanocomposite modification has attracted much attention in improving properties of bio-based polymer coating material for coated fertilizer. Herein two comparable polyhedral oligomeric silsesquioxanes (POSS), with eight poly(ethylene glycol) (PEG) and octaphenyl groups attached to the cage, respectively, were successfully incorporated into thin castor oil-based polyurethane coatings via in-situ polymerization on the urea surface. The nanostructure coatings are environmentally friendly, easy to prepare, and property-tunable. The results show that the vertex group of POSS had a pronounced influence on dispersion level and interaction between polyurethane and POSS that well-tuned the release pattern and period of coated urea, even at the coating rate as low as of 2 wt%. The liquid POSS with long and flexible PEG groups had better compatibility and dispersibility in polyurethane matrix than the solid POSS with rigid octaphenyl groups, as evidenced by SEM/EDS. The unique properties were resulted from the different extents of physical crosslinkings. This modification of bio-based polyurethane coating with POSS provided an alternative method of regulating and controlling the properties of coated fertilizer.

Polyurethane composite coatings on urea granules were prepared by SBA-15 mesoporous silica (in as-synthesized and calcined forms) as a pseudo-crosslinker without any other chain extenders. The calcination of mesoporous silica leaded to reduction of hydroxyl groups and increase of mesopores. The composite coating containing calcined SBA-15 showed enhanced controlled release properties compared with the other two coatings. At the loading content of 1 wt%, the initial release rate and release duration of urea coated by polyurethane/calcined SBA-15 composite were 0.08% and 83 d, respectively. It is shown that the calcination played an important role in controlling the properties of composite coating.