Search Results (365)

The excessive use of conventional NPK fertilizers can reduce nutrient use efficiency due to nutrient losses, emphasizing the need for controlled-release fertilizer systems. This study aimed to prepare and evaluate olive pomace-derived biochar (BC) as a carrier for nitrogen–phosphorus–potassium (NPK) fertilizer and assess its effects on nutrient release and lettuce performance. Biochar was produced by pyrolysis at 400 °C and loaded with NPK fertilizer. The BC/NPK composite was characterized using Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), nutrient-release behavior was evaluated in deionized water and soil. The cumulative nutrient release reached 64% in deionized water and 91% in soil. Under greenhouse conditions, BC/NPK applied at 100% and 75% NPK rates increased lettuce fresh weight, plant height and leaf number to 163.33 and 183.67 g, 23.00 and 23.67 cm, 34 and 36, respectively. Moreover, BC/NPK reduced nitrate accumulation in lettuce leaves, with nitrate concentrations decreasing in outer leaves to 10 and 0.73 mg g⁻¹ and in inner leaves to 2 and 1.33 mg g⁻¹ at the 100% and 75% rates, respectively. These findings demonstrate that olive pomace-derived BC/NPK is a promising slow-release fertilizer capable of improving crop performance while supporting sustainable nutrient management and agricultural waste valorization. Full article

Reintroducing crop straw into soil boosts organic matter, but natural crop straw usually shows low nutrient content. To enhance the water absorption rate of a certain thin sheet-shaped iron-containing material, a technical approach combining ball milling, the Mannich reaction, Schiff’s base cross-linking, emulsion separation, and solid–liquid adsorption was attempted to prepare iron-containing microspheres using sodium alginate and rice straw as raw materials. This approach increased the content of the trace nutrient iron and improved the water absorption rate. The results indicated that the iron-containing microspheres exhibit a diameter ranging from approximately 15 μm, an iron content of 10.44%, and a water absorption rate of 501.76%. The release rates of iron and nitrogen in soil and water within the first day were all below 15%, while the release rates after 30 days in soil were 61.8% for iron and 44.32% for nitrogen, and the corresponding rates in water were 73.1% for iron and 63.88% for nitrogen. The water absorption capacity of the iron-containing microspheres showed a trend associated with particle size and pore structure parameters. The development of iron-containing microspheres has expanded the preparation technology for semi-interpenetrating structure type sustained-release materials, and holds the potential for further development into slow-release fertilizers. Full article

Phosphorus scarcity and inefficient fertilizer utilization highlight the need for sustainable phosphorus recovery and reuse strategies. In this study, a Zn/Fe-layered double hydroxide (Zn/Fe-LDH)-kelp-derived biochar (KBC) composite (Zn/Fe-LDH@0.5KBC) was synthesized via co-precipitation for phosphate capture and subsequent reutilization as a slow-release fertilizer. The incorporation of KBC improved the dispersion of LDH nanosheets and generated a hierarchical porous structure with a specific surface area of 122.13 m²/g. As a result, Zn/Fe-LDH@0.5KBC exhibited a high phosphate adsorption capacity of 132.52 mg P/g and reached adsorption equilibrium within 240 min. Kinetic and isotherm analyses indicated that phosphate adsorption was dominated by chemisorption and was best described by the Sips model. Comprehensive scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses revealed that phosphate removal occurred through synergistic mechanisms, including electrostatic attraction, interlayer anion exchange, surface complexation, and metal phosphate precipitation. The P-loaded composite exhibited diffusion-dominated phosphorus release in soil and significantly enhanced pak choi growth. Compared with the control, labile phosphorus increased from 2.8% to 6.8%, while moderately labile phosphorus increased from 6.3% to 14.1%, indicating improved phosphorus availability. These findings demonstrate an effective strategy for integrating phosphate recovery from wastewater with agricultural reuse and provide insights into the development of multifunctional adsorbent-fertilizer systems for circular phosphorus management. Full article

Baijiu brewing generates large quantities of wastewater sludge, which presents major disposal challenges but contains abundant organic matter and nutrients, indicating great potential as a soil amendment. This study investigated the soil amendment effects of granulated and coated Baijiu brewing sludge through a 112-day soil column leaching experiment. Sludge particles were coated with sodium alginate (SA), polyvinyl alcohol (PVA), and ester gum (EG), and compared with untreated air-dried sludge (CK₁), uncoated granulated sludge (CK₂), compound fertilizer (F), and a blank control (B). The results showed that coated sludge treatments significantly increased soil leachate pH, total organic carbon, total nitrogen, total phosphorus, and total potassium, and exhibited obvious controlled-release effects on nitrogen, phosphorus, and potassium nutrients compared with uncoated sludge. Soil enzyme analysis indicated that SA treatment increased catalase activity, acid phosphatase activity was generally enhanced by sludge addition, and urease activity was reduced in coated sludge treatments. FTIR and BET analysis showed that both coated and uncoated sludge increased soil-specific surface area and changed soil pore structure. These findings confirm that granulated and coated Baijiu brewing sludge can be used as an effective slow-release soil amendment, and sodium alginate coating shows the most comprehensive improvement in multiple soil health indicators, with high application value for resource utilization of Baijiu sludge and soil quality improvement. Full article

Climate change and population growth are intensifying global food security challenges by reducing agricultural productivity and increasing reliance on fertilizers. In this context, developing sustainable and economically efficient agricultural solutions becomes essential. The study presents the synthesis of an interpenetrating polymer network (IPN) of hydrogels by combining bacterial cellulose (BC) with poly(acrylic acid) crosslinked with N, N-methylene-bis-acrylamide (PAA–co–MBA) via free radical copolymerization. To explore their potential as bioactive compound carriers, an ethanolic hydroalcoholic phytoextract (EHP) obtained from Hypericum perforatum L. and Melissa officinalis L. was directly encapsulated within the IPN hydrogels. The EHP is valued for its rich bioactive profile and antifungal, antimycobacterial, and antioxidant properties. The results of rheology measurements and thermal gravimetric analysis (TGA) revealed that incorporating BC into the IPN hydrogels significantly enhanced the mechanical stiffness, thermal resistance, and overall stability of the resulting IPN structures. Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) confirmed the structural organization and the porosity of the developed composite, as well as the successful fabrication of IPN hydrogels in the EHP medium. Under optimal conditions, the IPN hydrogels exhibited a reduced swelling capacity, thereby slowing the diffusion of the bioactive agents, reducing the application frequency, and enhancing the utilization efficiency. Taken together with the controlled-release performance, these findings demonstrate the potential of BC (PAA-co-MBA) IPN hydrogels as biodegradable and sustainable carrier systems for controlled delivery applications and suggest that they may be promising candidates for hydrogel-based agricultural delivery systems. Full article

Chemical fertilizers are widely used to achieve rapid and high-yield crop production. However, their intensive use negatively impacts ecosystems by polluting air and groundwater, accelerating soil acidification and deterioration, and because they rely on energy-intensive production processes and excessive mining. Biofertilizers have emerged as a promising and sustainable solution. Among them, microalgae, particularly species of the genus Chlorella, have attracted significant attention. Chlorella microalgae are an eco-friendly and cost-effective biofertilizer option, with advantages such as ease of cultivation, fast growth and slow release of nutrients when applied to soil. In this context, this review summarizes the potential of Chlorella species as biofertilizers and highlights the important role of its phytohormones in this effect, in addition to its use in wastewater treatment, which results in biomass and water with biofertilizing potential. Full article

Calcium alginate is an anionic polysaccharide that forms an ionically crosslinked hydrogel network with encapsulation properties to nucleic acids and nutrients for the amelioration of osmotic stress, ion toxicity and nutrient imbalance in saline–alkali soils. Traditional soil reclamation methods, including salt leaching, incorporation of organic matter, and gypsum application, are water-intensive under a changing climate, ultimately necessitating transformative bio-based solutions for food security. Calcium alginate-based biohydrogel represents a versatile platform with a tunable macromolecular architecture, ionic crosslinking via an “egg box” mechanism and potentially promising to deliver engineered co-encapsulated nutrients and genetically modified cargoes. The mannuronic (M) and guluronic (G) acid (M/G) ratios govern ion exchange capacity, rheological behavior and release kinetics in saline- and alkali-stressed environments. Recent studies on alginate-based nutrient encapsulation showed reduced oxidative damage and a 15–50% increase in plant-available water. The irrigation intervals extended from 7 to 14 days and yield gains by 24% in wheat, with comparable improvements in maize, tomato, rice and cotton. Calcium alginate hydrogels encapsulated salt tolerance genes (HKT1, SOS1, AVP1) encoding proteins mainly involved in Na⁺ retrieval from xylem, Na⁺ extrusion from root cells and vacuolar Na⁺ sequestration, which have achieved yield gains of 40 to 75% across wheat, rice and maize. Future research should focus on optimizing mechanical strength, crosslinking chemistry and smart bioencapsulation strategies for sustainable development so that crops are capable of withstanding variable climate stresses. Full article

Ammonia (NH₃) emissions from fertilized cropland are influenced by conservation tillage practices, yet the underlying mechanisms remain insufficiently understood in the black soil region of northeastern China. In this study, field observations were conducted in a maize cropland to compare NH₃ volatilization under conventional tillage, no-tillage, and straw incorporating treatments following application of urea and slow-release fertilizer. Results showed that compared with conventional tillage, no-tillage-straw mulching (T1) and ridge tillage-straw mulching (T3) treatments significantly reduced soil temperature while increasing soil moisture and decreasing the estimated soil resistance to NH₃ transport. These changes were accompanied by higher NH₃ emission factors (EFs) in the T1 and T3 treatments, although differences in EFs among tillage treatments were not statistically significant. Compared with urea, slow-release fertilizer delayed the occurrence of peak NH₃ volatilization and reduced cumulative NH₃ emissions by approximately 54%. Notably, measurements under slow-release fertilizer application revealed that elevated NH₃ volatilization persisted for more than 40 days after fertilization, indicating that conventional monitoring periods may underestimate cumulative NH₃ losses in conservation tillage systems using slow-release fertilizers. Overall, conservation tillage substantially altered soil environmental conditions associated with NH₃ volatilization, while fertilizer types strongly influenced the temporal dynamics and magnitude of NH₃ emissions. These findings provide useful insights for improving NH₃ emission monitoring, process understanding, and inventory estimation in conservation tillage systems. Full article

Excess phosphate in aquatic environments can trigger eutrophication and pose risks to ecosystem integrity and public health, even though phosphate is indispensable for plant growth. Herein, we report the fabrication of Zr-LDHs-PS hydrogel microspheres by in situ cross-linking zirconium–magnesium–iron layered double hydroxides (ZrMgFe-LDHs) with Polyvinyl alcohol (PVA) and sodium alginate (SA). The resulting bead-type adsorbent was designed to enable efficient phosphate capture from water while facilitating subsequent, controlled phosphate release. Benefiting from the cross-linking granulation strategy, the microspheres mitigate typical limitations of powdered adsorbents, including compaction, aggregation, and poor separability. General characterization (SEM, FT-IR, XPS, XRD, BET, TG, and zeta potential) elucidated the microstructure and surface chemical composition. The Zr-LDHs-PS microspheres exhibited a maximum experimental adsorption capacity of 51.313 mg/g. Kinetics data were best fitted by the pseudo-second-order model, and adsorption isotherms were subjected to the Freundlich model, pointing to heterogeneous, multilayer adsorption. Importantly, high phosphate selectivity was preserved despite the coexistence of competing anions (Cl⁻, NO₃⁻, and CO₃²⁻). After adsorption, the spent beads released phosphate gradually in water, highlighting their potential for dual functionality. Collectively, these results demonstrate that Zr-LDHs-PS hydrogel microspheres are promising candidates for extraction-based phosphate removal and resource recovery, with prospects for repurposing slow-release phosphate fertilizers to support sustainable plant nutrition. Full article

Phallus indusiatus is a prestigious macro-fungus with both nutritional and medicinal significance. However, its industrial development is limited by low yields and inconsistent quality, largely due to an incomplete understanding of the underlying soil microecological mechanisms. In this study, field experiments were conducted to measure soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), and pH across different growth stages. High-throughput sequencing was further employed to characterize the dynamic successions of bacterial and fungal communities. The results revealed a continuous depletion of SOC throughout the growth cycle, with a marked decrease in TN during the ovoid stage, whereas TP, TK, and pH showed increasing trends. Bacterial abundance followed a fluctuating “increase–decrease–increase” pattern, reaching its lowest level during the ovoid stage; similarly, fungal abundance initially decreased and subsequently increased, also attaining its minimum at the ovoid stage. Based on these stage-specific soil dynamics, targeted management strategies are proposed, including the application of basal carbon fertilizers supplemented with low-concentration phosphorus and potassium, the integration of slow-release nitrogen fertilizers, and the inoculation of functional microbes such as Massilia, Acidobacteriaceae, and Terriglobales. Dynamic regulation of soil pH is also recommended. This study provides a theoretical framework and technical guidance for the sustainable and high-efficiency cultivation of P. indusiatus and contributes to the broader development of the edible fungus industry. Full article

Rapid dissolution of conventional fertilizers causes low nutrient-use efficiency and serious leaching losses, contributing to agricultural non-point source pollution. In this study, biomass-based slow-release fertilizer beads were prepared by ionic crosslinking of potato starch (ST), chitosan (CS), and corn-straw biochar (BC), using potassium nitrate (KNO₃) as the model nutrient. The effects of ST/CS ratio and BC incorporation on bead structure, swelling, nutrient loading, release kinetics, and soil-column leaching were systematically investigated. Biochar incorporation formed a more compact and interconnected porous network and reduced the equilibrium swelling ratios of ST90/CS10, ST80/CS20, and ST70/CS30 from 188%, 176%, and 164% to 168%, 136%, and 104%, respectively. Although BC slightly decreased KNO₃ loading capacity, it markedly slowed nutrient release; ST80/CS20/BC20 released 31.09%, 50.09%, and 81.82% of loaded KNO₃ at 24, 72, and 504 h, respectively, which were 28.40%, 25.27%, and 11.30% lower than those of ST80/CS20. Kinetic fitting indicated that BC reduced the apparent release rate and promoted diffusion-controlled release behavior. Soil-column experiments further showed that the beads reduced NO₃⁻-N and K⁺ leaching compared with free KNO₃, with ST80/CS20/BC20 showing the best balance between nutrient loading and release control. These results suggest that starch–chitosan–biochar beads are a promising biodegradable matrix for slow-release fertilizer applications. Full article

Optimizing speed breeding protocols for biennial crops requires matching the vernalization regime with the genetic background. In this study, nine sugar beet genotypes were exposed to 12, 13, 14 or 15 weeks of vernalization and subsequently grown under controlled speed breeding conditions. Survival analysis revealed a threshold-like acceleration of bolting and flowering: 12 and 13 weeks were largely equivalent, whereas 14–15 weeks sharply increased the bolting and flowering hazard rates. Genotypic variation strongly influenced reproductive success and seed yield traits; genotype MARGARITA KWS combined early flowering with the highest seed number (361 seeds per plant) and total seed weight (5.26 g), while genotype 1K073 did not flower under any vernalization duration. A separate mini-steckling root architecture experiment with 11 genotypes showed that slow-release Osmocote fertilizer significantly increased mini-steckling fresh weight, length and width, with the strongest responses in genotypes 1K073, 1K139 and SMART LIENNA KWS. The interaction between genotype and nutrition was significant for mini-steckling fresh weight and width, indicating that optimal nutrition can modulate the expression of genotypic differences. Multivariate analyses (PCA, CVA, Mahalanobis distances) confirmed that vernalization duration had a threshold-type effect and that genotype was the dominant factor for seed traits, whereas nutrition was the main driver of mini-steckling architecture. Overall, these findings suggest that tailoring vernalization duration and nutrition to the genetic background may substantially improve the efficiency of sugar beet speed breeding. Full article

In this study, the amination-based modification of kraft lignin (KL) was implemented through phenolization treatment combined with the Mannich reaction to synthesize the aminated lignin (APKL) with high nitrogen content. Afterward, the chemical structural changes and reaction mechanism of KL during the modification process were surveyed in depth using diverse analytical techniques. The results revealed that the phenolization treatment markedly raised the active site number in KL from 5.79 to 25.5 mmol/g, which led to a significant increase in the chemical reactivity of KL. Meanwhile, the amine group was successfully grafted onto the best phenolized kraft lignin (PKL) after the Mannich reaction. Furthermore, the effects of amination reagent, reactant mass ratio, temperature and time on the nitrogen content of APKL were systematically examined to optimize the reaction conditions for amination. Using FTIR, molecular weight and elemental analyses, the optimal amination conditions were determined as a reaction temperature of 75 °C, reaction time of 3 h and PKL₆/arginine/formaldehyde mass ratio of 3:21:28. Under these parameters, APKL₁₀ with a higher nitrogen content of 19.2% and lower C/N ratio of 2.46 was acquired. In addition, TG and SEM results revealed that the obtained APKL₁₀ possessed a flake-like structure and outstanding thermal stability, which was beneficial for its subsequent application as a slow-release soil fertilizer. More importantly, the soil column leaching test confirmed that the as-prepared APKL₁₀ had excellent nitrogen slow-release properties in the soil. As a result, this kraft lignin derivative generated by phenol treatment followed by amination-based modification could serve as an efficient nitrogen fertilizer, providing a long-term nitrogen source for plant growth in soil. Full article

In southern China, Chinese milk vetch is used as green manure to substitute for inorganic nitrogen (N) fertilizers and improve soil fertility, but how different incorporation methods affect its decomposition and underlying microbial mechanisms is unclear. This study used four fertilization regimes (CK: no N; CF: sole chemical N; CM: sole vetch; CMCF: vetch + 40% reduced N) to evaluate bacterial diversity, community composition and life history strategies during early vetch decomposition, and the nylon bag method to compare decomposition and C/N release dynamics. The results show that vetch dry matter decomposition reached 81.9–85.2% in 34 days, slowing to 11.8–14.4% after 192 days. CMCF significantly accelerated early decomposition and N release compared with CM. While CMCF reduced the bacterial Ace and Chao indices compared to CK with similar community structure, CF/CM exhibited distinct community structures. Compared to CM, CMCF increased r-strategy bacteria (e.g., Proteobacteria, Bacteroidota) and decreased K-strategy ones (e.g., Chloroflexi). Furthermore, decomposition rate positively correlated with r-strategy and negatively with K-strategy bacteria, with soil temperature as the primary driver. Compared to CMCF, CM reduced bacterial network complexity, decreasing nodes by 63.6% and average degree by 68.5%. In conclusion, combining vetch with chemical N enhances vetch residue decomposition while preserving microbial network structure and functional diversity. Full article

We hypothesized that the application of digestate (D) to winter oilseed rapeseed would have the same effect on seed production as nitrogen fertilizer (N_f). It impacts yield by altering the mass of readily available N in the vegetative and reproductive periods of plant growth. This allows for a good yield forecast. This hypothesis was assessed in field experiments with rapeseed carried out in 2015/2016, 2016/2017, and 2017/2018. The experiment included three N fertilization systems (FSs): AN, based on ammonium nitrate (AN); D, with digestate-based N; DAN, using ²/₃ of digestate + ¹/₃ of AN—and five N_f doses: 0, 80, 120, 160, and 240 kg N ha⁻¹. The net seed yield increase due to N application was 1.44 t ha⁻¹ in the AN system, 1.53 t ha⁻¹ in D, and 1.77 t ha⁻¹ in DAN. The optimal N rates were 160, 250, and 224 kg N ha⁻¹. The N economy of winter oilseed rapeseed was assessed in two periods: vegetative—before anthesis (from the rosette stage to the beginning of anthesis, BBCH 30–BBCH 60) and reproductive (from the beginning of anthesis to full maturity, BBCH 60–BBCH 89). The mass of available N at the beginning of anthesis increased by 54.3% (151 kg N ha⁻¹ to 233 N ha⁻¹) and doubled (151 kg N ha⁻¹ to 302 kg N ha⁻¹) compared to its value at the rosette stage, taking into account the mass of N in the rapeseed canopy and its total mass in the soil/rapeseed continuum. No differences in NUE were found for the tested N carriers. The net increase in N available resources resulting from the application of N fertilizer was 55.1, 104.9, 102.8, and 93.0 kg N ha⁻¹ for respective plots fertilized with 60, 120, 180, and 240 kg N ha⁻¹. Three N indices were measured at the beginning of rapeseed anthesis—N in crop biomass (NAF, r = 0.87 ***), N balance (Nb60, r = 0.87 ***), and N released from soil resources (Ngain60, r = 0.79 ***)—and showed potential for seed yield (SEY) prediction. The linear dependence of SEY on these indicators indicates that the potential of the rapeseed canopy to effectively accumulate N during the vegetative growth was too low. This limitation was fully confirmed by analogous N management indicators, but developed for rapeseed during the seed-filling period. The key indicator of SEY at harvest was the N mass in rapeseed biomass (NAH, r = 0.95 ***). N from digestate acted as a slow-release fertilizer, giving it an advantage over ammonium nitrate. In summary, digestate is an optimal N carrier under conditions of average rapeseed yield. Full article