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Keywords = potassium balance

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13 pages, 1841 KiB  
Article
Valorizing Biomass Waste: Hydrothermal Carbonization and Chemical Activation for Activated Carbon Production
by Fidel Vallejo, Diana Yánez, Luis Díaz-Robles, Marcelo Oyaneder, Serguei Alejandro-Martín, Rasa Zalakeviciute and Tamara Romero
Biomass 2025, 5(3), 45; https://doi.org/10.3390/biomass5030045 - 5 Aug 2025
Abstract
This study optimizes the production of activated carbons from hydrothermally carbonized (HTC) biomass using potassium hydroxide (KOH) and phosphoric acid (H3PO4) as activating agents. A 23 factorial experimental design evaluated the effects of agent-to-precursor ratio, dry impregnation time, [...] Read more.
This study optimizes the production of activated carbons from hydrothermally carbonized (HTC) biomass using potassium hydroxide (KOH) and phosphoric acid (H3PO4) as activating agents. A 23 factorial experimental design evaluated the effects of agent-to-precursor ratio, dry impregnation time, and activation duration on mass yield and iodine adsorption capacity. KOH-activated carbons achieved superior iodine numbers (up to 1289 mg/g) but lower mass yields (18–35%), reflecting enhanced porosity at the cost of material loss. Conversely, H3PO4 activation yielded higher mass retention (up to 54.86%) with moderate iodine numbers (up to 1117.3 mg/g), balancing porosity and yield. HTC pretreatment at 190 °C reduced the ash content, thereby enhancing the stability of hydrochar. These findings highlight the trade-offs between adsorption performance and process efficiency, with KOH suited for high-porosity applications (e.g., water purification) and H3PO4 for industrial scalability. The study advances biomass waste valorization, aligning with circular economy principles and offering sustainable solutions for environmental and industrial applications, such as water purification and energy storage. Full article
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18 pages, 2365 KiB  
Article
Integrated Environmental–Economic Assessment of CO2 Storage in Chinese Saline Formations
by Wentao Zhao, Zhe Jiang, Tieya Jing, Jian Zhang, Zhan Yang, Xiang Li, Juan Zhou, Jingchao Zhao and Shuhui Zhang
Water 2025, 17(15), 2320; https://doi.org/10.3390/w17152320 - 4 Aug 2025
Abstract
This study develops an integrated environmental–economic assessment framework to evaluate the life cycle environmental impacts and economic costs of CO2 geological storage and produced water treatment in saline formations in China. Using a case study of a saline aquifer carbon storage project [...] Read more.
This study develops an integrated environmental–economic assessment framework to evaluate the life cycle environmental impacts and economic costs of CO2 geological storage and produced water treatment in saline formations in China. Using a case study of a saline aquifer carbon storage project in the Ordos Basin, eight full-chain carbon capture, utilization, and storage (CCUS) scenarios were analyzed. The results indicate that environmental and cost performance are primarily influenced by technology choices across carbon capture, transport, and storage stages. The scenario employing potassium carbonate-based capture, pipeline transport, and brine reinjection after a reverse osmosis treatment (S5) achieved the most balanced outcome. Breakeven analyses under three carbon price projection models revealed that carbon price trajectories critically affect project viability, with a steadily rising carbon price enabling earlier profitability. By decoupling CCUS from power systems and focusing on unit CO2 removal, this study provides a transparent and transferable framework to support cross-sectoral deployment. The findings offer valuable insights for policymakers aiming to design effective CCUS support mechanisms under future carbon neutrality targets. Full article
(This article belongs to the Special Issue Mine Water Treatment, Utilization and Storage Technology)
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20 pages, 2457 KiB  
Article
Exploring the Influence of NaOH Catalyst on the Durability of Liquid Calcium Aluminate Cement Concrete
by Chung-Lin Lin, Chia-Jung Tsai, Leila Fazeldehkordi, Wen-Shinn Shyu, Chih-Wei Lu and Jin-Chen Hsu
Materials 2025, 18(15), 3655; https://doi.org/10.3390/ma18153655 - 4 Aug 2025
Viewed by 56
Abstract
Liquid calcium aluminate cement (LCAC) is an innovative material technology with significant potential for varied applications in civil engineering. However, despite its promising results, a significant gap remains in the direct application of LCAC as a concrete binder. The primary catalysts for LCAC [...] Read more.
Liquid calcium aluminate cement (LCAC) is an innovative material technology with significant potential for varied applications in civil engineering. However, despite its promising results, a significant gap remains in the direct application of LCAC as a concrete binder. The primary catalysts for LCAC are sodium hydroxide (NaOH) and potassium hydroxide (KOH). Therefore, it is crucial to investigate the effects of sodium and potassium ions on alkali–aggregate reactions in concrete structures. This study evaluated the durability of liquid calcium aluminate cement concrete catalyzed using four different concentrations of NaOH (0.5%, 1.0%, 1.5%, and 2.0%) as experimental variables, incorporating a control group of traditional concrete with a water–cement ratio of 0.64. The findings indicate that NaOH catalysis in the concrete significantly trigger alkali–aggregate reactions, leading to volume expansion. Furthermore, it increased chloride ion penetration and porosity in the concrete. These effects were more notable with the increase in NaOH concentration. The results suggested that NaOH catalysis can enhance certain chemical reactions within the concrete matrix; however, its concentration must be carefully controlled to mitigate adverse effects. The NaOH dosage should be limited to 0.5% to ensure optimal durability of the concrete. This study emphasizes the crucial importance of precisely balancing catalyst concentration to maintain the long-term durability and performance of liquid calcium aluminate cement concrete in structural applications. Full article
(This article belongs to the Section Construction and Building Materials)
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17 pages, 5265 KiB  
Article
Influence of Agricultural Practices on Soil Physicochemical Properties and Rhizosphere Microbial Communities in Apple Orchards in Xinjiang, China
by Guangxin Zhang, Zili Wang, Huanhuan Zhang, Xujiao Li, Kun Liu, Kun Yu, Zhong Zheng and Fengyun Zhao
Horticulturae 2025, 11(8), 891; https://doi.org/10.3390/horticulturae11080891 (registering DOI) - 1 Aug 2025
Viewed by 189
Abstract
In response to the challenges posed by soil degradation in the arid regions of Xinjiang, China, green and organic management practices have emerged as effective alternatives to conventional agricultural management methods, helping to mitigate soil degradation by promoting natural soil recovery and ecological [...] Read more.
In response to the challenges posed by soil degradation in the arid regions of Xinjiang, China, green and organic management practices have emerged as effective alternatives to conventional agricultural management methods, helping to mitigate soil degradation by promoting natural soil recovery and ecological balance. However, most of the existing studies focus on a single management practice or indicator and lack a systematic assessment of the effects of integrated orchard management in arid zones. This study aims to investigate how different agricultural management practices influence soil physicochemical properties and inter-root microbial communities in apple orchards in Xinjiang and to identify the main physicochemical factors affecting the composition of inter-root microbial communities. Inter-root soil samples were collected from apple orchards under green management (GM), organic management (OM), and conventional management (CM) in major apple-producing regions of Xinjiang. Microbial diversity and community composition of the samples were analyzed using high-throughput amplicon sequencing. The results revealed significant differences (p < 0.05) in soil physicochemical properties across different management practices. Specifically, GM significantly reduced soil pH and C:N compared with OM. Both OM and GM significantly decreased soil available nutrient content compared with CM. Moreover, GM and OM significantly increased bacterial diversity and changed the community composition of bacteria and fungi. Proteobacteria and Ascomycota were identified as the dominant bacteria and fungi, respectively, in all management practices. Linear discriminant analysis (LEfSe) showed that biomarkers were more abundant under OM, suggesting that OM may contribute to ecological functions through specific microbial taxa. Co-occurrence network analysis (building a network of microbial interactions) demonstrated that the topologies of bacteria and fungi varied across different management practices and that OM increased the complexity of microbial co-occurrence networks. Mantel test analysis (analyzing soil factors and microbial community correlations) showed that C:N and available potassium (AK) were significantly and positively correlated with the community composition of bacteria and fungi, and that C:N, soil organic carbon (SOC), and alkaline hydrolyzable nitrogen (AN) were significantly and positively correlated with the diversity of fungi. Redundancy analysis (RDA) further indicated that SOC, C:N, and AK were the primary soil physicochemical factors influencing the composition of microbial communities. This study provides theoretical guidance for the sustainable management of orchards in arid zones. Full article
(This article belongs to the Section Fruit Production Systems)
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16 pages, 2729 KiB  
Article
Effect of Enterobacter bugandensis R-18 on Maize Growth Promotion Under Salt Stress
by Xingguo Tian, Qianru Liu, Jingjing Song, Xiu Zhang, Guoping Yang, Min Li, Huan Qu, Ahejiang Tastanbek and Yarong Tan
Microorganisms 2025, 13(8), 1796; https://doi.org/10.3390/microorganisms13081796 - 31 Jul 2025
Viewed by 253
Abstract
Soil salinization poses a significant constraint to agricultural productivity. However, certain plant growth-promoting bacteria (PGPB) can mitigate salinity stress and enhance crop performance. In this study, a bacterial isolate, R-18, isolated from saline-alkali soil in Ningxia, China, was identified as Enterobacter bugandensis based [...] Read more.
Soil salinization poses a significant constraint to agricultural productivity. However, certain plant growth-promoting bacteria (PGPB) can mitigate salinity stress and enhance crop performance. In this study, a bacterial isolate, R-18, isolated from saline-alkali soil in Ningxia, China, was identified as Enterobacter bugandensis based on 16S rRNA gene sequencing. The isolate was characterized for its morphological, biochemical, and plant growth-promoting traits and was evaluated for its potential to alleviate NaCl-induced stress in maize (Zea mays L.) under hydroponic conditions. Isolate R-18 exhibited halotolerance, surviving at NaCl concentrations ranging from 2.0% to 10.0%, and alkaliphilic adaptation, growing at pH 8.0–11.0. Biochemical assays confirmed it as a Gram-negative bacterium, displaying positive reactions in the Voges–Proskauer (V–P) tests, catalase activity, citrate utilization, fluorescent pigment production, starch hydrolysis, gelatin liquefaction, and ammonia production, while testing negative for the methyl red and cellulose hydrolysis. Notably, isolate R-18 demonstrated multiple plant growth-promoting attributes, including nitrogen fixation, phosphate and potassium solubilization, ACC deaminase activity, and indole-3-acetic acid (IAA) biosynthesis. Under 100 mM NaCl stress, inoculation with isolate R-18 significantly enhanced maize growth, increasing plant height, stem dry weight, root fresh weight, and root dry weight by 20.64%, 47.06%, 34.52%, and 31.25%, respectively. Furthermore, isolate R-18 improved ion homeostasis by elevating the K+/Na+ ratio in maize tissues. Physiological analyses revealed increased chlorophyll and proline content, alongside reduced malondialdehyde (MDA) levels, indicating mitigated oxidative damage. Antioxidant enzyme activity was modulated, with decreased superoxide dismutase (SOD) and peroxidase (POD) activities but increased catalase (CAT) activity. These findings demonstrated that Enterobacter bugandensis R-18 effectively alleviated NaCl-induced growth inhibition in maize by enhancing osmotic adjustment, reducing oxidative stress, and improving ion balance. Full article
(This article belongs to the Section Plant Microbe Interactions)
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15 pages, 288 KiB  
Article
Association of Dietary Sodium-to-Potassium Ratio with Nutritional Composition, Micronutrient Intake, and Diet Quality in Brazilian Industrial Workers
by Anissa Melo Souza, Ingrid Wilza Leal Bezerra, Karina Gomes Torres, Gabriela Santana Pereira, Raiane Medeiros Costa and Antonio Gouveia Oliveira
Nutrients 2025, 17(15), 2483; https://doi.org/10.3390/nu17152483 - 29 Jul 2025
Viewed by 239
Abstract
Introduction: The sodium-to-potassium (Na:K) ratio in the diet is a critical biomarker for cardiovascular and metabolic health, yet global adherence to recommended levels remains poor. Objectives: The objective of this study was to identify dietary determinants of the dietary Na:K ratio and its [...] Read more.
Introduction: The sodium-to-potassium (Na:K) ratio in the diet is a critical biomarker for cardiovascular and metabolic health, yet global adherence to recommended levels remains poor. Objectives: The objective of this study was to identify dietary determinants of the dietary Na:K ratio and its associations with micronutrient intake and diet quality. Methods: An observational cross-sectional survey was conducted in a representative sample of manufacturing workers through a combined stratified proportional and two-stage probability sampling plan, with strata defined by company size and industrial sector from the state of Rio Grande do Norte, Brazil. Dietary intake was assessed using 24 h recalls via the Multiple Pass Method, with Na:K ratios calculated from quantified food composition data. Diet quality was assessed with the Diet Quality Index-International (DQI-I). Multiple linear regression was used to analyze associations of Na:K ratio with the study variables. Results: The survey was conducted in the state of Rio Grande do Norte, Brazil, in 921 randomly selected manufacturing workers. The sample mean age was 38.2 ± 10.7 years, 55.9% males, mean BMI 27.2 ± 4.80 kg/m2. The mean Na:K ratio was 1.97 ± 0.86, with only 0.54% of participants meeting the WHO recommended target (<0.57). Fast food (+3.29 mg/mg per serving, p < 0.001), rice, bread, and red meat significantly increased the ratio, while fruits (−0.16 mg/mg), dairy, white meat, and coffee were protective. Higher Na:K ratios were associated with lower intake of calcium, magnesium, phosphorus, and vitamins C, D, and E, as well as poorer diet quality (DQI-I score: −0.026 per 1 mg/mg increase, p < 0.001). Conclusions: These findings highlight the critical role of processed foods in elevating Na:K ratios and the potential for dietary modifications to improve both electrolyte balance and micronutrient adequacy in industrial workers. The study underscores the need for workplace interventions that simultaneously address sodium reduction, potassium enhancement, and overall diet quality improvement tailored to socioeconomic and cultural contexts, a triple approach not previously tested in intervention studies. Future studies should further investigate nutritional consequences of imbalanced Na:K intake. Full article
(This article belongs to the Special Issue Mineral Nutrition on Human Health and Disease)
18 pages, 2358 KiB  
Article
Characterizing the Temporally Dynamic Nature of Relative Growth Rates: A Kinetic Analysis on Nitrogen-, Phosphorus-, and Potassium-Limited Growth
by Andrew Sharkey, Asher Altman, Yuming Sun, Thomas K. S. Igou and Yongsheng Chen
Agriculture 2025, 15(15), 1641; https://doi.org/10.3390/agriculture15151641 - 29 Jul 2025
Viewed by 251
Abstract
Developing precision models to describe agricultural growth is a necessary step to promote sustainable agriculture and increase resource circulation. In this study, the researchers hydroponically cultivated Bibb lettuce (Lactuca sativa) across a variety of nitrogen, phosphorus, and potassium (NPK)-limited treatments and [...] Read more.
Developing precision models to describe agricultural growth is a necessary step to promote sustainable agriculture and increase resource circulation. In this study, the researchers hydroponically cultivated Bibb lettuce (Lactuca sativa) across a variety of nitrogen, phosphorus, and potassium (NPK)-limited treatments and developed robust data-driven kinetic models observing nutrient uptake, biomass growth, and tissue composition based on all three primary macronutrients. The resulting Dynamic μ model is the first to integrate plant maturity’s impact on growth rate, significantly improving model accuracy across limiting nutrients, treatments, and developmental stages. This reduced error supports this simple expansion as a practical and necessary inclusion for agricultural kinetic modeling. Furthermore, analysis of nutrient uptake refines the ideal hydroponic nutrient balance for Bibb lettuce to 132, 35, and 174 mg L−1 (N, P, and K, respectively), while qualitative cell yield analysis identifies minimum nutrient thresholds at approximately 26.2–41.7 mg-N L−1, 3.7–5.6 mg-P L−1, and 17.4–31.5 mg-K L−1 to produce compositionally healthy lettuce. These findings evaluate reclaimed wastewater’s ability to offset the fertilizer burden for lettuce by 23–45%, 14–57%, and 3–23% for N, P, and K and guide the required minimum amount of wastewater pre-processing or nutrient supplements needed to completely fulfill hydroponic nutrient demands. Full article
(This article belongs to the Section Agricultural Systems and Management)
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12 pages, 1421 KiB  
Article
Enzymatic Stoichiometry and Driving Factors Under Different Land-Use Types in the Qinghai–Tibet Plateau Region
by Yonggang Zhu, Feng Xiong, Derong Wu, Baoguo Zhao, Wenwu Wang, Biao Bi, Yihang Liu, Meng Liang and Sha Xue
Land 2025, 14(8), 1550; https://doi.org/10.3390/land14081550 - 28 Jul 2025
Viewed by 149
Abstract
Eco-enzymatic stoichiometry provides a basis for understanding soil ecosystem functions, with implications for land management and ecological protection. Long-term climatic factors and human interferences have caused significant land-use transformations in the Qinghai–Tibet Plateau region, affecting various ecological functions, such as soil nutrient cycling [...] Read more.
Eco-enzymatic stoichiometry provides a basis for understanding soil ecosystem functions, with implications for land management and ecological protection. Long-term climatic factors and human interferences have caused significant land-use transformations in the Qinghai–Tibet Plateau region, affecting various ecological functions, such as soil nutrient cycling and chemical element balance. It is currently unclear how large-scale land-use conversion affects soil ecological stoichiometry. In this study, 763 soil samples were collected across three land-use types: farmland, grassland, and forest land. In addition, changes in soil physicochemical properties and enzyme activity and stoichiometry were determined. The soil available phosphorus (SAP) and total phosphorus (TP) concentrations were the highest in farmland soil. Bulk density, pH, SAP, TP, and NO3-N were lower in forest soil, whereas NH4+-N, available nitrogen, soil organic carbon (SOC), available potassium, and the soil nutrient ratio increased. Land-use conversion promoted soil β-1,4-glucosidase, N-acetyl-β-glucosaminidase, and alkaline phosphatase activities, mostly in forest soil. The eco-enzymatic C:N ratio was higher in farmland soils but grassland soils had a higher enzymatic C:P and N:P. Soil microorganisms were limited by P nutrients in all land-use patterns. C limitation was the highest in farmland soil. The redundancy analysis indicated that the ecological stoichiometry in farmland was influenced by TN, whereas grass and forest soils were influenced by SOC. Overall, the conversion of cropland or grassland to complex land-use types can effectively enhance soil nutrients, enzyme activities, and ecosystem functions, providing valuable insights for ecological restoration and sustainable land management in alpine regions. Full article
(This article belongs to the Section Land Use, Impact Assessment and Sustainability)
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15 pages, 1843 KiB  
Article
Multidimensional Evaluation of Local Rye Bread Fortified with Whey as a Model for Food Waste Valorization: From Recipe Development to Consumer Acceptance
by Márcio Moura-Alves, João Mota, Diogo Lameirão, Ana Francisca Teixeira, Cristina Saraiva, María Ángeles Romero-Rodríguez, Alice Vilela and Carla Gonçalves
Sustainability 2025, 17(15), 6710; https://doi.org/10.3390/su17156710 - 23 Jul 2025
Viewed by 311
Abstract
The growing demand for functional and sustainable foods has driven food innovation, enhancing its nutritional value. This study aimed to develop a nutritious bread using local rye from the Trás-os-Montes region of Portugal and incorporating whey, a by-product of the dairy industry, as [...] Read more.
The growing demand for functional and sustainable foods has driven food innovation, enhancing its nutritional value. This study aimed to develop a nutritious bread using local rye from the Trás-os-Montes region of Portugal and incorporating whey, a by-product of the dairy industry, as a replacement for water. Three bread formulations were tested: a traditional recipe with 37.5% rye flour and water (Control—CTR); the same recipe using whey instead of water (Rye Whey—RW); and a formulation with 100% local rye and whey replacing water (Full Rye Whey—FRW). Nutritional composition was assessed, including moisture, ash, protein, dietary fiber, sodium, potassium, lipids, and carbohydrates. Sensory analysis included both quantitative descriptive analysis and consumer acceptance testing. Microbiological quality was also evaluated. Whey-containing samples showed lower moisture and increased levels of ash, lipids, carbohydrates, and potassium. RW had the highest protein content (6.54 ± 0.28 g/100 g, p < 0.05), while FRW exhibited the highest dietary fiber (6.96 ± 0.15 g/100 g, p < 0.05). RW demonstrated a balanced nutritional and sensory profile, with high consumer acceptance. Overall, the combination of local rye and whey presents a promising strategy for producing nutritious bread while valorizing local agricultural resources and dairy by-products. These findings support sustainable food production practices and contribute to circular economy approaches. Full article
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35 pages, 1745 KiB  
Article
Balanced Fertilization of Winter Wheat with Potassium and Magnesium—An Effective Way to Manage Fertilizer Nitrogen Sustainably
by Agnieszka Andrzejewska, Katarzyna Przygocka-Cyna and Witold Grzebisz
Sustainability 2025, 17(15), 6705; https://doi.org/10.3390/su17156705 - 23 Jul 2025
Viewed by 419
Abstract
In agricultural practice, in addition to determining the nitrogen (Nf) dose, it is necessary to effectively control its effect on currently grown crops. Meeting these conditions requires not only the use of phosphorus (P) and potassium (K), but also nutrients such [...] Read more.
In agricultural practice, in addition to determining the nitrogen (Nf) dose, it is necessary to effectively control its effect on currently grown crops. Meeting these conditions requires not only the use of phosphorus (P) and potassium (K), but also nutrients such as magnesium (Mg) and sulfur (S). This hypothesis was verified in a single-factor field experiment with winter wheat (WW) carried out in the 2015/2016, 2016/2017, and 2017/2018 growing seasons. The experiment consisted of seven variants: absolute control (AC), NP, NPK-MOP (K as Muriate of Potash), NPK-MOP+Ki (Kieserite), NPK-KK (K as Korn–Kali), NPK-KK+Ki, and NPK-KK+Ki+ES (Epsom Salt). The use of K as MOP increased grain yield (GY) by 6.3% compared to NP. In the NPK-KK variant, GY was 13% (+0.84 t ha−1) higher compared to NP. Moreover, GYs in this fertilization variant (FV) were stable over the years (coefficient of variation, CV = 9.4%). In NPK-KK+Ki+ES, the yield increase was the highest and mounted to 17.2% compared to NP, but the variability over the years was also the highest (CV ≈ 20%). The amount of N in grain N (GN) increased progressively from 4% for NPK-MOP to 15% for NPK-KK and 25% for NPK-KK+Ki+ES in comparison to NP. The nitrogen harvest index was highly stable, achieving 72.6 ± 3.1%. All analyzed NUE indices showed a significant response to FVs. The PFP-Nf (partial factor productivity of Nf) indices increased on NPK-MOP by 5.8%, NPK-KK by 12.9%, and NPK-KK+Ki+ES by 17.9% compared to NP. The corresponding Nf recovery of Nf in wheat grain was 47.2%, 55.9%, and 64.4%, but its total recovery by wheat (grain + straw) was 67%, 74.5%, and 87.2%, respectively. In terms of the theoretical and practical value of the tested indexes, two indices, namely, NUP (nitrogen unit productivity) and NUA (nitrogen unit accumulation), proved to be the most useful. From the farmer’s production strategy, FV with K applied in the form of Korn–Kali proved to be the most stable option due to high and stable yield, regardless of weather conditions. The increase in the number of nutritional factors optimizing the action of nitrogen in winter wheat caused the phenomenon known as the “scissors effect”. This phenomenon manifested itself in a progressive increase in nitrogen unit productivity (NUP) combined with a regressive trend in unit nitrogen accumulation (NUA) in the grain versus the balance of soil available Mg (Mgb). The studies clearly showed that obtaining grain that met the milling requirements was recorded only for NUA above 22 kg N t−1 grain. This was possible only with the most intensive Mg treatment (NPK-KK+Ki and NPK-KK+Ki+ES). The study clearly showed that three of the six FVs fully met the three basic conditions for sustainable crop production: (i) stabilization and even an increase in grain yield; (ii) a decrease in the mass of inorganic N in the soil at harvest, potentially susceptible to leaching; and (iii) stabilization of the soil fertility of P, K, and Mg. Full article
(This article belongs to the Special Issue Soil Fertility and Plant Nutrition for Sustainable Cropping Systems)
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26 pages, 3919 KiB  
Article
Impacts of Various Straw Mulching Strategies on Soil Water, Nutrients, Thermal Regimes, and Yield in Wheat–Soybean Rotation Systems
by Chaoyu Liao, Min Tang, Chao Zhang, Meihua Deng, Yan Li and Shaoyuan Feng
Plants 2025, 14(14), 2233; https://doi.org/10.3390/plants14142233 - 19 Jul 2025
Viewed by 336
Abstract
Straw mulching is an important strategy for regulating soil moisture, nutrient availability, and thermal conditions in agricultural systems. However, the mechanisms by which the mulching period, thickness, and planting density interact to influence yield formation in wheat–soybean rotation systems remain insufficiently understood. In [...] Read more.
Straw mulching is an important strategy for regulating soil moisture, nutrient availability, and thermal conditions in agricultural systems. However, the mechanisms by which the mulching period, thickness, and planting density interact to influence yield formation in wheat–soybean rotation systems remain insufficiently understood. In this study, we systematically examined the combined effects of straw mulching at the seedling and jointing stages of winter wheat, as well as varying mulching thicknesses and soybean planting densities, on soil properties and crop yields through field experiments. The experimental design included straw mulching treatments during the seedling stage (T1) and the jointing stage (T2) of winter wheat, with soybean planting densities classified as low (D1, 1.8 × 105 plants·ha−1) and high (D2, 3.6 × 105 plants·ha−1). Mulching thicknesses were set at low (S1, 2830.19 kg·ha−1), medium (S2, 8490.57 kg·ha−1), and high (S3, 14,150.95 kg·ha−1), in addition to a no-mulch control (CK) for each treatment. The results demonstrated that (1) straw mulching significantly increased soil water content in the order S3 > S2 > S1 > CK and exerted a temperature-buffering effect. This resulted in increases in soil organic carbon, available phosphorus, and available potassium by 1.88−71.95%, 1.36−165.8%, and 1.92−36.34%, respectively, while decreasing available nitrogen content by 1.42−17.98%. (2) The T1 treatments increased wheat yields by 1.22% compared to the control, while the T2 treatments resulted in a 23.83% yield increase. Soybean yields increased by 23.99% under D1 and by 36.22% under D2 treatments. (3) Structural equation modeling indicated that straw mulching influenced yields by modifying interactions among soil organic carbon, available nitrogen, available phosphorus, available potassium, bulk density, soil temperature, and soil water content. Wheat yields were primarily regulated by the synergistic effects of soil temperature, water content, and available potassium, whereas soybean yields were determined by the dynamic balance between organic carbon and available potassium. This study provides empirical evidence to inform the optimization of straw return practices in wheat–soybean rotation systems. Full article
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20 pages, 2217 KiB  
Article
Organic Nitrogen Substitution Enhances Carbon Sequestration but Increases Greenhouse Gas Emissions in Maize Cropping Systems
by Yanan Liu, Xiaoqing Zhao, Yuchen Cheng, Rui Xie, Tiantian Meng, Liyu Chen, Yongfeng Ren, Chunlei Xue, Kun Zhao, Shuli Wei, Jing Fang, Xiangqian Zhang, Fengcheng Sun and Zhanyuan Lu
Agronomy 2025, 15(7), 1703; https://doi.org/10.3390/agronomy15071703 - 15 Jul 2025
Viewed by 348
Abstract
Excessive chemical fertilizers degrade soil and increase greenhouse gas (GHG) emissions. Organic substitution of nitrogen fertilizers is recognized as a sustainable agricultural-management practice, yet its dual role in carbon sequestration and emissions renders the net GHG balance (NGHGB) uncertain. To assess the GHG [...] Read more.
Excessive chemical fertilizers degrade soil and increase greenhouse gas (GHG) emissions. Organic substitution of nitrogen fertilizers is recognized as a sustainable agricultural-management practice, yet its dual role in carbon sequestration and emissions renders the net GHG balance (NGHGB) uncertain. To assess the GHG mitigation potential of organic substitution strategies, this study analyzed GHG fluxes, soil organic carbon (SOC) dynamics, indirect GHG emissions, and Net Primary Productivity (NPP) based on a long-term field positioning experiment initiated in 2016. Six fertilizer regimes were systematically compared: no fertilizer control (CK); only phosphorus and potassium fertilizer (PK); total chemical fertilizer (NPK); 1/3 chemical N substituted with sheep manure (OF1); dual substitution protocol with 1/6 chemical N substituted by sheep manure and 1/6 substituted by straw-derived N (OF2); complete chemical N substitution with sheep manure (OF3). The results showed that OF1 and OF2 maintained crop yields similar to those under NPK, whereas OF3 reduced yield by over 10%; relative to NPK, OF1, OF2, and OF3 significantly increased SOC sequestration rates by 50.70–149.20%, reduced CH4 uptake by 7.9–70.63%, increased CO2 emissions by 1.4–23.9%, decreased N2O fluxes by 3.6–56.2%, and mitigated indirect GHG emissions from farm inputs by 24.02–63.95%. The NGHGB was highest under OF1, 9.44–23.99% greater than under NPK. These findings demonstrate that partial organic substitution increased carbon sequestration, maintained crop yields, whereas high substitution rates increase the risk of carbon emissions. The study results indicate that substituting 1/3 of chemical nitrogen with sheep manure in maize cropping systems represents an effective fertilizer management approach to simultaneously balance productivity and ecological sustainability. Full article
(This article belongs to the Section Agroecology Innovation: Achieving System Resilience)
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18 pages, 3234 KiB  
Article
Optimization of Hydroponic Wheat Sprouts as an Alternative Livestock Feed: Yield and Biochemical Composition Under Different Fertilization Regimes
by Andrius Grigas, Dainius Steponavičius, Indrė Bručienė, Ričardas Krikštolaitis, Tomas Krilavičius, Aušra Steponavičienė and Dainius Savickas
Plants 2025, 14(14), 2166; https://doi.org/10.3390/plants14142166 - 14 Jul 2025
Viewed by 347
Abstract
This study investigated the effects of macronutrient type and concentration on the biomass yield and biochemical composition of hydroponically grown wheat sprouts (HWS), with the aim of identifying fertilization strategies that optimize both productivity and feed quality. HWS were cultivated using a nutrient [...] Read more.
This study investigated the effects of macronutrient type and concentration on the biomass yield and biochemical composition of hydroponically grown wheat sprouts (HWS), with the aim of identifying fertilization strategies that optimize both productivity and feed quality. HWS were cultivated using a nutrient film technique over a 7-day period under controlled environmental conditions, with treatments including calcium nitrate (CN1–CN3), potassium phosphate (CP1–CP3), potassium sulfate (CK1–CK2), and a balanced NPK 20–20–20 fertilizer (NPK1–NPK3), each applied at three increasing concentrations. The quantitative parameters assessed included biomass yield per unit of dry seed (DP, kg kg−1) and dry matter content (DM, %), while qualitative traits included crude protein (CP), ether extract (EE), crude fiber (CF), and ash content. Results indicated that balanced NPK fertilization significantly enhanced performance, with NPK3 achieving the highest biomass yield (6.39 kg kg−1), CP (24.26%), CF (5.63%), and ash (16.0%) content. In contrast, CN3 treatments reduced yield (4.84 kg kg−1) despite increasing CP (19.65%), indicating trade-offs between nitrogen enrichment and vegetative expansion. Phosphorus-based treatments (CP2–CP3) improved nutrient density without suppressing yield. Regression analyses revealed strong correlations between DM and both CF (R2 = 0.81) and ash (R2 = 0.71), supporting their utility as indirect indicators of feed quality. EE content remained stable (2.07–2.67%) across all treatments, suggesting its limited responsiveness to macronutrient manipulation. These findings highlight the importance of nutrient synergy in hydroponic systems and provide a practical framework for tailoring fertilization regimes to meet specific agronomic and nutritional objectives in precision livestock feeding and provide practical guidance for optimizing hydroponic livestock feed production. Full article
(This article belongs to the Special Issue Strategies for Nutrient Use Efficiency Improvement in Plants)
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20 pages, 5984 KiB  
Article
Potassium Fulvate Alleviates Salinity and Boosts Oat Productivity by Modifying Soil Properties and Rhizosphere Microbial Communities in the Saline–Alkali Soils of the Qaidam Basin
by Jie Wang, Xin Jin, Xinyue Liu, Yunjie Fu, Kui Bao, Zhixiu Quan, Chengti Xu, Wei Wang, Guangxin Lu and Haijuan Zhang
Agronomy 2025, 15(7), 1673; https://doi.org/10.3390/agronomy15071673 - 10 Jul 2025
Viewed by 403
Abstract
Soil salinization severely limits global agricultural sustainability, particularly across the saline–alkaline landscapes of the Qinghai–Tibet Plateau. We examined how potassium fulvate (PF) modulates oat (Avena sativa L.) performance, soil chemistry, and rhizospheric microbiota in the saline–alkaline soils of the Qaidam Basin. PF [...] Read more.
Soil salinization severely limits global agricultural sustainability, particularly across the saline–alkaline landscapes of the Qinghai–Tibet Plateau. We examined how potassium fulvate (PF) modulates oat (Avena sativa L.) performance, soil chemistry, and rhizospheric microbiota in the saline–alkaline soils of the Qaidam Basin. PF markedly boosted shoot and root biomass, with the greatest response observed at 150 kg hm−2. At the same time, it enhanced soil fertility by increasing organic matter, nitrate-N, ammonium-N, and available potassium, and improved ionic balance by lowering Na+ concentrations and the sodium adsorption ratio (SAR), while increasing Ca2+ levels and soil moisture content. Under the high-dose treatment (F2), endogenous fungal contributions declined sharply, exogenous replacements increased, and fungal α-diversity fell; multivariate ordinations confirmed that PF reshaped both bacterial and fungal communities, with fungi exhibiting the stronger response. We integrated three machine learning algorithms—least absolute shrinkage and selection operator (LASSO), Random Forest (RF), and eXtreme Gradient Boosting (XGBoost)—to minimize the bias inherent in any single method. We identified microbial β-diversity, organic matter, and Na+ and Ca2+ concentrations as the most robust predictors of the Soil Salinization and Alkalization Index (SSAI). Structural equation modeling further showed that PF mitigates salinity chiefly by improving soil physicochemical properties (path coefficient = −0.77; p < 0.001), with microbial assemblages acting as key intermediaries. These findings provide compelling theoretical and empirical support for deploying PF to rehabilitate saline–alkaline soils in alpine environments and offer practical guidance for sustainable land management in the Qaidam Basin. Full article
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29 pages, 7438 KiB  
Article
Comparison of High-Efficiency MgO/Na2CO3 and MgO/K2CO3 as Heterogeneous Solid Base Catalysts for Biodiesel Production from Soybean Oil
by Xiangyang Li, Xunxiang Jia, Weiji Li, Shufan Jia, Siwei Zhang, Jiliang Song and Jiao Wang
Molecules 2025, 30(13), 2876; https://doi.org/10.3390/molecules30132876 - 7 Jul 2025
Viewed by 386
Abstract
As a renewable alternative to fossil fuels, the industrial production of biodiesel urgently requires the development of efficient and recyclable solid base catalysts. In this study, the physicochemical properties and catalytic performance differences between MgO/Na2CO3 and MgO/K2CO3 [...] Read more.
As a renewable alternative to fossil fuels, the industrial production of biodiesel urgently requires the development of efficient and recyclable solid base catalysts. In this study, the physicochemical properties and catalytic performance differences between MgO/Na2CO3 and MgO/K2CO3 catalysts were systematically compared using soybean oil as the raw material. By regulating the calcination temperature (500–700 °C), alcohol-to-oil ratio (3:1–24:1), and metal carbonate loading (10–50%), combined with N2 adsorption–desorption, CO2-TPD, XRD, SEM-EDS, and cycling experiments, the regulatory mechanisms of the ionic radius differences between sodium and potassium on the catalyst structure and performance were revealed. The results showed that MgO/Na2CO3-600 °C achieved a FAME yield of 97.5% under optimal conditions, which was 1.7% higher than MgO/K2CO3-600 °C (95.8%); this was attributed to its higher specific surface area (148.6 m2/g vs. 126.3 m2/g), homogeneous mesoporous structure, and strong basic site density. In addition, the cycle stability of MgO/K2CO3 was significantly lower, retaining only 65.2% of the yield after five cycles, while that of MgO/Na2CO3 was 88.2%. This stability difference stems from the disparity in their solubility in the reaction system. K2CO3 has a higher solubility in methanol (3.25 g/100 g at 60 °C compared to 1.15 g/100 g for Na2CO3), which is also reflected in the ion leaching rate (27.7% for K+ versus 18.9% for Na+). This study confirms that Na+ incorporation into the MgO lattice can optimize the distribution of active sites. Although K+ surface enrichment can enhance structural stability, the higher leaching rate leads to a rapid decline in catalyst activity, providing a theoretical basis for balancing catalyst activity and durability in sustainable biodiesel production. Full article
(This article belongs to the Special Issue Catalytic Green Reductions and Oxidations, 2nd Edition)
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