Search Results (2,201)

Under the condition of straw returning to the field, appropriate nitrogen fertilizer application is one of the key factors used to improve crop yield and ensure environmental safety. Therefore, an experiment with different rates of nitrogen fertilization was conducted with a randomized block design in Harbin, China. The straw was deeply plowed back into the field after harvest in the autumn. The nitrogen application rates were 0, 75, 150, 180, 225, and 300 kg·ha⁻¹. The purpose of this study is to clarify the appropriate amount of nitrogen fertilizer under the condition of straw returning to the field and to provide technical support for high-yield and high-efficiency maize in cold regions. The results indicated that the yield of maize first increased and then stabilized as the amount of nitrogen fertilizer increased, while the economic benefits first increased and then decreased. When the nitrogen application rate exceeds 225 kg·ha⁻¹ or is lower than 150 kg·ha⁻¹, the economic benefits significantly decrease. When high-nitrogen fertilizer rates of 225 kg·ha⁻¹ and 300 kg·ha⁻¹ were applied, the residual nitrate nitrogen in the soil was increased by 2.1 times and 2.3 times, respectively, compared to before sowing. With the increase in the nitrogen application rate, the nitrogen fertilizer utilization efficiency and agronomic efficiency decreased, and the apparent nitrogen loss and nitrogen surplus significantly increased. Comprehensively considering the maize yield, benefits, and environmental risk factors the suitable nitrogen application rate was in a range of 170.2 kg·ha⁻¹ to 178.2 kg·ha⁻¹ in the first year and 150.0 kg·ha⁻¹ to 171.3 kg·ha⁻¹ in the second year. This work provides a theoretical basis and technical support for the rational application of nitrogen fertilizer and high-yield and high-efficiency spring maize under the condition of straw returning to the field. Full article

Nitrogen is a critical nutrient that influences plant growth and resistance to pathogens; however, its impact on disease dynamics, particularly downy mildew infection, and the associated physiological responses in cucumber during early growth stages remains poorly understood. To evaluate the combined effects of downy mildew (caused by Pseudoperonospora cubensis) infection and nitrogen application on cucumber growth and physiological traits during the seedling and vine development stages, two downy mildew treatments— infected (B0) and non-infected(B1)—and three nitrogen levels—T1 (N-50%), T2 (N-100%), and T3 (N-150%)—were applied. Significant differences were observed between all treatments (p < 0.05). Among them, the B1T3 treatment had the most pronounced stimulatory effect, particularly on growth parameters (such as plant height, stem diameter, and leaf area). Without any disease infection (B1), the B1T2 treatment showed an increasing trend in photosynthetic rate and a more notable rise in stomatal conductance. In contrast, with downy mildew infection (B0), photosynthetic rates declined under B0T1 and B0T2. Moreover, with downy mildew infection (B0), the intracellular CO₂ concentration, stomatal conductance, and transpiration rate of cucumber leaves decreased in the B0T1, B0T2, and B0T3 treatments. Plant height, stem diameter, and leaf area responded variably to nitrogen levels and downy mildew infection. The total root length, root surface area, average root diameter, total root volume, and total root tips of cucumber plants were significantly different under different experimental conditions (p < 0.05). Consequently, this study provides a theoretical basis for stress-resistant cucumber cultivation in greenhouses and has practical implications for advancing the sustainable development of the greenhouse cucumber industry. Full article

The growing potassium (K) demand and supply–demand imbalance in intensive agriculture require the development of multi-nutrient K fertilizers. Polyhalite (POLY), a multi-nutrient natural mineral rich in K, calcium, magnesium, and sulfur, can enhance soil nutrient diversity and fertility. However, research on its synergistic application with nitrogen (N) fertilizer remains limited. Therefore, this study was designed to apply three different fertilizer composites at four N concentration gradients through field plot experiments to evaluate crop productivity and nutrient use efficiency. Results revealed that the application of both compound fertilizers with N fertilizer increased maize yield, ranging from 1.03% to 11.53%, compared with the PK control. Moreover, 25-7-8 (MOP)(POLY26%) achieved a maximum yield of 9499.88 kg/ha at the N1 (170 kg/ha) level. This represents a significant increase of 11.53% compared with the PK control. Moreover, the application of compound fertilizer containing POLY could significantly increase the N fertilizer utilization rate; improve the quality of maize; and exert a significant effect on soil pH, EC, and nutrient content. This study paves the way for broader application of POLY by establishing its novel role as a sustainable nutrient source. It provides critical strategic guidance for advancing global resource-efficient agriculture. Full article

The problems of excessive nitrogen fertilizer application and mismatch between varieties and planting density are common in potato production in the dryland farming areas of Loess Plateau, and it is of great significance to select suitable nitrogen application rates and planting densities for the green and sustainable production of dryland potatoes in this area. In this study, Longshu 16 was selected as the potato variety, and we investigated two nitrogen application rates: 200 kg·hm⁻² (N1), 300 kg·hm⁻² (N2); and three planting densities: 37,500 plants·hm⁻² (D1), 52,500 plants·hm⁻² (D2), 67,500 plants·hm⁻² (D3). The effects of different nitrogen fertilization rates and planting densities on photosynthetic characteristics, leaf carbon and nitrogen metabolism enzyme activities, and yield and quality of potato were measured and analyzed. The results showed that during the tuber swelling stage, the activity of ribose-1,5-diphosphate carboxylase oxygenase (Rubisco) in potato leaves was increased by 9.05%. During the starch accumulation stage, the activity of glutamine synthetase (GS) in potato leaves was increased by 3.02~22.34% in N1D2 treatment compared with other treatments, and the activity of glutamate synthase (GOGAT) was increased by 2.83~7.35% compared with other treatments. During the starch accumulation stage, the activity of ADP-glucose pyrophosphorylase (AGPase) in potato leaves was increased by 7.85~31.17% in N1D2 treatment compared with other treatments. The contents of protein, starch, vitamin C, and calcium in potato tubers in N1D2 treatment were the highest, and the yield was the highest in N1D2 treatment. In conclusion, the recommended nitrogen application rate of 200 kg·hm⁻² and planting density of 52,500 plants·hm⁻² in dry-fed potato production improved the yield and quality of potato by enhancing activities of GAPDH, GS, and AGPase. Full article

Urban lawns are a predominant form of vegetation in sports grounds and greenbelts. Nitrogen (N) fertilization is widely used to sustain lawn productivity. However, it also promotes nitrous oxide (N₂O) emissions, a potent greenhouse gas. The microbial mechanisms underlying N₂O emissions from fertilized lawn soils remain poorly understood. In this study, we conducted a controlled incubation experiment with four N application rates [0 (N0), 100 (N100), 200 (N200), and 300 kg·ha⁻¹·yr⁻¹ (N300)] to investigate N₂O emissions and associated microbial processes in urban lawn soil. Biological inhibitors combined with high-throughput sequencing were used to quantify the inhibitor-sensitive fraction of fungi and bacteria contributing to N₂O emissions. Our results showed that N fertilizer significantly increased N₂O emissions, with the highest emission observed under N200. The fungi inhibitor-sensitive fraction accounted for ~45% of total N₂O emissions, significantly higher than that of bacteria (~31%). Dominant fungal phyla included Ascomycota, Basidiomycota, and Zygomycota, with N fertilization significantly increasing the relative abundance of Ascomycota and decreasing that of Basidiomycota. Redundancy analysis revealed strong positive correlations between Ascomycota abundance and N₂O emissions across N treatments. At the genus level, Pyrenochaetopsis, Myrothecium, and Humicola were positively associated with N₂O production and identified as key functional taxa. These findings demonstrate that moderate N fertilization can disproportionately stimulate fungal-driven N₂O emissions in urban lawns. The results provide a scientific basis for optimizing N fertilization strategies in green spaces, with implications for N policy and sustainable landscape management. Full article

Bermudagrass (Cynodon dactylon) forage production recommendations are often developed in natural environments with available water limitations, often resulting in highly variable responses and lower average responses. As farmland ownership changes and agriculture and irrigation technologies become more affordable the amount of irrigated hay production has increased. While much of the agronomic management does not differ between rain-fed and irrigated environments, nutrient use and uptake dynamics may. This requires a reevaluation and potential adjustment of current recommendations to allow for increased yield potential of irrigated production systems without detrimental impacts on the system. The objective of this study was to identify the need for further investigation of nitrogen application rates for forage bermudagrass production under irrigated conditions. Nitrogen applications of 0 to 280 kg N ha⁻¹, in 56 kg increments, were applied at spring green-up and following the first and second harvests. Dry matter biomass, crude protein, and total digestible nutrients increased with increasing nitrogen application rate, while yield and profit maximizing rates both exceeded the typical recommended rate for bermudagrass hay production. The responses noted for increased nitrogen application rates indicate the need for further investigation of N requirements of non-moisture-limited hay production. Full article

This study presents the preparation of iron and nitrogen co-doped sludge-based biochar (FeCN-MSBC) and iron oxide-doped biochar (FeO-MSBC) by ball milling municipal sludge with different iron precursors (K₃Fe(CN)₆ and Fe₂O₃), followed by pyrolysis. These biochars were utilized to activate persulfate (PMS) for the degradation of phenolic pollutants. The results demonstrate that FeCN-MSBC, formed by the introduction of K₃Fe(CN)₆, contains Fe/N phases, with surface Fe sites exhibiting a lower oxidation state, which significantly enhances PMS activation efficiency. In contrast, FeO-MSBC, due to the aggregation of Fe₂O₃/Fe₃O₄, shows relatively lower catalytic activity. The FeCN-MSBC/PMS system degrades pollutants via a synergistic mechanism involving non-radical pathways mediated by ¹O₂ and electron transfer processes (ETP) catalyzed by surface Fe. Electrochemical oxidation and quenching experiments confirm that ETP is the dominant pathway. FeCN-MSBC, prepared at a pyrolysis temperature of 600 °C and an Fe loading of 3 mmol/g TSS, exhibited the best performance, achieving a phenol degradation rate constant (k_obs) of 0.127 min⁻¹, 4.5 times higher than that of undoped biochar (MSBC). FeCN-MSBC/PMS maintained high efficiency across a wide pH range and in complex water matrices, exhibiting excellent stability over multiple cycles, demonstrating strong potential for practical applications. This study provides an effective strategy for simultaneous Fe and N doping in sludge-derived biochar and offers mechanistic insights into Fe/N synergistic activation of PMS for practical water treatment. Full article

Swine manure poses significant challenges for anaerobic digestion due to its low carbon-to-nitrogen (C/N) ratio and elevated ammonia concentrations, both of which restrict methane generation. This study investigated the impact of integrating low-intensity ultrasound with co-digestion of piggery wastewater and food waste leachate. Laboratory-scale upflow anaerobic sludge blanket (UASB) reactors were employed under four operational conditions to evaluate anaerobic digestion performance, track shifts in microbial community structure, and assess the abundance of antibiotic resistance genes (ARGs). Co-digestion significantly enhanced methane production, yielding 1.3–3.2 times more than manure alone, while low-intensity ultrasound further increased methane yields by approximately 36–44% at high loading rates. Moreover, coupling low-intensity ultrasound with co-digestion led to the most rapid recovery following an overloading shock. Unexpectedly, ultrasound treatment alone increased the expression of certain ARGs (tetG, sul1, ermB) and the Integrase gene (intI1), while co-digestion led to a reduction in these genetic markers. These findings clearly indicate that the concurrent application of co-digestion and low-intensity ultrasound achieved the highest methane yield, the fastest recovery after organic overloading, and greater suppression of specific ARGs. Full article

Efficient water and nitrogen (N) management are essential for sustaining potato (Solanum tuberosum L.) production under limited resource conditions. This study investigated the effects of deficit irrigation and reduced N application on tuber quality parameters including specific gravity (SG), starch content (SC), and tuber dry matter (TDM) as well as agronomic water use efficiency (WUE) and nitrogen use efficiency (NUE) in four commercial potato cultivars (Canela Russet, Mesa Russet, Russet Norkotah 3, and Yukon Gold) over two seasons (2016 and 2017) at Colorado State University’s San Luis Valley Research Center. Three irrigation levels (100%, ~80%, and ~70% evapotranspiration replacement) and two N application rates (165 and 131 kg N ha⁻¹) were evaluated using four replications. Moderate deficit irrigation (up to ~18% ET reduction) improved or maintained SG, SC, and TDM in all four cultivars, while severe deficit irrigation (~30–40% reduction) reduced tuber quality. Reduced N application improved NUE in all cultivars without compromising tuber quality or yield. While WUE responded variably to deficit irrigation, NUE was highest under moderate to full irrigation and low N rate. Although effects on WUE were variable, integrating moderate deficit irrigation (18%) with reduced N application (20%) enhanced NUE while maintaining tuber quality. Full article

Background/Objectives: Hemp (Cannabis sativa L. subsp. sativa) is a plant within the Cannabis sativa species and utilized for several applications, including antioxidation, antihypertension, and anti-inflammation. To our knowledge, no prior study has assessed the acute and sub-chronic oral safety of hemp leaf oil in Sprague-Dawley rats under Thailand-compliant THC levels. This study investigates the acute and sub-chronic effects of Hemp leaf oil (HLO) on the heart, liver, and kidneys of male and female Sprague-Dawley rats. Methods: Six-week-old male and female Sprague-Dawley rats were administered HLO (1.5 mL/kg) intragastrically, either as a single dose or a repeat dose over 28 days. Results: No changes in body or organ weights were observed following acute and sub-chronic HLO administration in sex-matched groups. Moreover, blood pressure and heart rate remained comparable across groups after acute and sub-chronic HLO treatment. Both acute and sub-chronic administration of HLO did not influence electrolyte balance, liver enzymes, total protein, albumin, blood urea nitrogen, or creatinine levels. Hematoxylin and eosin staining revealed the normal morphology of the heart, liver, and kidneys in rats subjected to HLO, during both acute and sub-chronic treatment. Conclusions: In conclusion, our data suggested that both acute and sub-chronic administration of HLO at 1.5 mL/kg could be safe for the vital organs. These findings support the potential use of HLO in therapeutic applications, particularly in scenarios when the safety of essential organs is at stake. Full article

Mesoporous silica materials with well-organized architectures were synthesized using a series of Pluronic PE-type triblock copolymers (PE6800, PE9200, PE9400, PE10500) as structure-directing agents under acidic conditions. The study aimed to elucidate the impact of synthesis parameters—copolymer type, presence of a swelling agent, 1,3,5-trimethylbenzene, aging temperature, and silica precursor—on the structural, textural, and functional properties of the resulting mesocellular foam materials. Characterization by Nitrogen Adsorption/Desorption, Transmission Electron Microscopy, X-ray Diffraction, and Small-angle X-ray Scattering revealed that structural ordering and pore morphology are significantly influenced by the EO/PO ratio of the copolymers and the use of the expander. Materials synthesized with PE9400 and PE10500 in the presence of a swelling agent exhibited highly uniform bottle-shaped mesopores with increased surface area and pore volume. Thermal behavior studied via Differential Scanning Calorimetry indicated a correlation between pore size and melting point depression of confined water, consistent with the Gibbs–Thomson effect. Adsorption capacity and kinetics for methylene blue varied significantly with pore structure, with materials possessing narrow mesopores showing superior dye uptake, and materials with larger mesopores and open-pore architecture exhibiting faster adsorption rates. This work demonstrates the tunability of mesoporous silica structure through precise control of synthesis conditions and highlights its potential in applications involving adsorption and phase phenomena in confined pore systems. Full article

Substituting chemical fertilizers with organic alternatives represents an effective strategy for mitigating soil nitrogen (N) loss and reducing chemical fertilizer use. However, the efficacy of organic substitution in regulating soil N fertility and rice growth requires further investigation, and mechanistic studies elucidating how organic fertilizers affect soil N transformation processes and availability are still deficient. To address this, we conducted a three-year field experiment from 2021 to 2023, comparing three rice fertilization regimes: (1) chemical fertilizer as the control (CK), (2) substitution with organic fertilizer (OF), and (3) substitution with biochar-based organic fertilizer (BF). Both organic substitution treatments were applied as basal fertilizer, and the rice plants received equivalent topdressing applications. The soil N availability, gross and net N transformation rates, and soil microbial activity were analyzed, and the rice growth index and yield were determined. The results showed that organic substitution (OF and BF) significantly increased the soil total carbon content, stimulated microbial biomass growth and enhanced enzymatic activity associated with soil C and N cycling. However, the limited N input from organic substitution significantly decreased the soil gross N mineralization rate by 28.30% (OF) and 58.14% (BF), compared to chemical fertilization (CK). It also reduced the gross N nitrification rate by 38.30% (OF) and 36.17% (BF). These suppressed N transformation processes ultimately led to 11.97% (OF) and 14.72% (BF) lower soil mineral N contents. The soil N deficiency during critical early vegetative growth stages substantially constrained rice development, resulting in significant yield reductions in the OF and BF treatments compared to chemical fertilization (CK). These results indicate that complete organic substitution compromises rice yields due to insufficient N availability; therefore, we recommend integrated organic–mineral fertilization as an optimal strategy to achieve both crop productivity and environmental benefits. Full article

Global food security is challenged by population growth and the environmental toll of conventional fertilizers. Enhancing biological nitrogen fixation (BNF) in legumes like soybean (Glycine max) is a sustainable fertilization alternative. This study investigates a graphitic carbon nitride/iron oxide (Fe₂O₃/g–C₃N₄ or FC) nanocomposite as a dual–functional fertilizer to improve iron (Fe) nutrition and BNF in soybeans. A pot experiment was conducted using different FC concentrations (10, 100, and 200 mg kg⁻¹), alongside controls. Results showed that the 100 mg kg⁻¹ FC treatment (FC2) was most effective, significantly increasing soybean biomass, nodule number, and nodule fresh weight. The FC2 treatment also enhanced photosynthetic rates and chlorophyll content (SPAD values) while reducing stomatal conductance and transpiration, indicating improved water–use efficiency. Furthermore, FC application bolstered the plant’s antioxidant system by increasing the activity of superoxide dismutase (SOD) and peroxidase (POD). Elemental analysis confirmed that FC treatments significantly increased the uptake and translocation of Fe and nitrogen (N) in plant tissues. These findings demonstrate that the FC nanocomposite acts as a highly effective nanofertilizer, simultaneously addressing iron deficiency and boosting nitrogen fixation to promote soybean growth. This work highlights its potential as a sustainable solution to enhance crop productivity and nutrient use efficiency in modern agriculture. Full article

Long-term maize (Zea mays L.) intercropping with peanut (Arachis hypogaea L.) (M||P) improves soil aggregate stability and phosphorus (P) availability, sustaining farmland productivity. In contrast, co-ridge planting (R-M||P) further enhances yield. However, the relationship between yield increase and improvements in soil aggregate stability and ecological stoichiometric characteristics under R-M||P remains unclear. Therefore, this study examined the effects of R-M||P on aggregate fractions and stability, bulk density (BD), porosity (Pt), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), total phosphorus (TP), and inorganic phosphorus, along with the ecological stoichiometric characteristics of C, N, and P. R-M||P substantially increased the proportion of topsoil macroaggregates, both mechanically stable (>0.5 mm) and water-stable (>1 mm), compared with flat planting. Additionally, it enhanced WR_0.25 and mean weight diameter, substantially reduced BD, and increased Pt. Furthermore, R-M||P significantly increased the concentrations of SOC, TN, TP, AP, Ca₂-P, Ca₈-P, Al-P, and Fe-P. It also enhanced the contribution rates of SOC, TN, TP, and AP in macroaggregates, leading to increased storage of carbon (SCS), nitrogen (SNS), and phosphorus (SPS). R-M||P significantly elevated C:N and C:P ratios. Phosphorus application increased SOC and nutrient concentrations, positively regulated C:N, and enhanced C, N, and P storage. However, it negatively influenced C:P and N:P ratios. SOC and AP were the main driving factors affecting the intercropping advantage, with explanatory rates of 33.2% and 22.7%, respectively, under R-M||P. These findings suggest that R-M||P combined with P application enhances yield by promoting aggregate stability, increasing the concentrations and storage of C, N, and P, and establishing a new ecological stoichiometric balance. Full article

To explore the effects of micro-nano aeration and oxygenation irrigation on soil characteristics and cotton growth in cotton fields in arid areas, this study was conducted at the National Soil Quality Aksu Observation and Experiment Station in Baicheng County, Xinjiang. “Xinluzao 78” cotton was used as the experimental material, and the soil column cultivation method was adopted. Four nitrogen concentration gradients (N0: 0 kg·hm⁻², NL: 112.5 kg·hm⁻², NM: 225 kg·hm⁻², and NH: 337.5 kg·hm⁻²) and two irrigation methods (micro-nano aeration and oxygenation irrigation Y: DO15 mg/L, conventional irrigation C: DO7.6 mg/L) were set up to systematically analyze the total nitrogen content of the soil, enzyme activity, microbial community structure, and the response characteristics of cotton growth and yield. The results show that aeration treatment significantly increases the total nitrogen content in the soil. The total nitrogen content in the 0–15 cm and 15–30 cm soil layers treated with YNM (aeration + local conventional nitrogen application rate) increased by 9.14% and 8.53%, respectively, compared with CNM. YNM treatment significantly increased the activities of soil urease, sucrase, and β-glucosidase, among which total nitrogen had the strongest correlation with the activity of β-glucosidase. Oxygenation significantly increased the richness of soil microorganisms. The Chao1 index of YNM-treated bacteria was 75.7% higher than that of CNM-treated bacteria. YNM treatment increased cotton yield by 26.73% compared with CNM treatment. Moreover, the number of bells formed per plant and the weight of the bells increased by 44.44% and 29.6%, respectively. In conclusion, micro-nano aeration and oxygenation irrigation effectively increase cotton yield. By optimizing the activities of soil enzymes and microorganisms, micro-nano aeration and oxygenation irrigation enhance the ability of cotton to utilize and transform nitrogen, and alleviate the impact of insufficient nitrogen utilization by cotton in arid areas. Full article