Agronomy

The aim of the study was to determine the effect of cultivar and nitrogen fertilization on the morphological and physiological traits and yield of soybean (Glycine max (L.) Merrill) grown in central-eastern Poland. In a strict, two-factor field experiment, four soybean cultivars were used: ‘Abelina’, ‘Malaga’, ‘Coraline’, and ‘Petrina’, and three nitrogen rates: 0, 30, and 60 kg N ha⁻¹. The moderate rate (N30) was applied before sowing, while the higher rate (N60) was divided into two parts, with 50% applied before sowing and 50% top-dressed at BBCH 61. The studies were conducted during two growing seasons. It was shown that both the cultivar and nitrogen fertilization significantly affected plant height, leaf area index (LAI), leaf greenness index (SPAD), and chlorophyll fluorescence indices (Fv/Fm, PI). The interaction among cultivar, fertilization, and years was significant for SPAD and Fv/Fm index, indicating a strong influence of environmental factors on plant response. Nitrogen fertilization increased plant height and chlorophyll content but reduced fluorescence indices. Among the cultivars studied, the late-season cultivar ‘Malaga’ was characterized by the highest SPAD index (502), Fv/Fm (0.800), and PI values (4.3), and achieved the highest seed yield (5.06 t ha⁻¹) and thousand-seed weight (230 g). In contrast, the medium-season cultivar ‘Abelina’ showed the lowest SPAD (454), and significantly lower Fv/Fm and PI values (0.790 and 3.51, respectively), resulting in the lowest yield (4.25 t ha⁻¹) and TSW (169.7 g). The application of a moderate rate of nitrogen (N30) improved the physiological indicators of plants and elements of yield structure without reducing the potential photochemical efficiency of PSII, while a higher rate (N60) did not result in a significant increase in yield, despite a greater number of pods and seeds per plant, which may have been due to a reduction in thousand-seed weight. The results highlight the importance of cultivar selection and moderate N fertilization of soybean grown in temperate climates and indicate the need for further research on the physiological mechanisms that determine cultivar-specific nitrogen use efficiency and yield stability under environmental stress.

This study explored the potential application of Lycium barbarum residue (LBR) in alfalfa silage, particularly focusing on its synergistic effects when combined with silage additives. Two controlled experiments were conducted. In Experiment 1, four treatment groups were established with different LBR addition levels (0, 70, 140, 210 g/kg fresh weight, FW). Experiment 2 used the optimal LBR level identified (210 g/kg FW), and further investigated the effects of additive combinations. The treatments in this experiment included: (1) 210 g/kg FW LBR (CK), (2) a combination of 210 g/kg FW LBR with lactic acid bacteria (ALL), (3) a combination of 210 g/kg FW LBR with molasses (ALM), and (4) a combination of 210 g/kg FW LBR with both lactic acid bacteria and molasses (ALLM). The silage was ensiled for 7, 15, 30, and 90 days. The results demonstrated that the incorporation of LBR significantly enhanced silage fermentation quality. The 210 g/kg treatment exhibited the most favorable outcomes, characterized by the lowest pH, reduced ammonia nitrogen content, and the highest concentration of lactic acid. Additionally, 210 g/kg treatment showed increased levels of total phenolics and flavonoids, as well as enhanced antioxidant activities as measured by DPPH (2,2-diphenyl-1-picrylhydrazyl radical scavenging activity), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity), and FRAP (ferric-reducing antioxidant power) assays. These improvements in bioactive compounds were positively correlated with lactic acid content and negatively associated with pH. Furthermore, in Experiment 2, the combined application of LAB and molasses along with LBR further optimized the silage quality, resulting in the lowest pH and ammonia nitrogen content, alongside a marked improvement in antioxidant capacity during the later ensiling stages. Overall, the study concludes that the inclusion of 210 g/kg LBR in combination with lactic acid bacteria and molasses effectively enhances both the fermentation process and the functional value of alfalfa silage, providing a scientific foundation for the utilization of agricultural byproducts.

Sugar beet (Beta vulgaris L.) is an important economic crop and a primary source of sugar in northern China, characterized by strong stress tolerance and high nutritional value. Microbial inoculants can promote crop growth by regulating soil enzyme activities, enriching dominant beneficial bacterial genera in rhizosphere soil, and improving the availability of soil nutrients. This study aimed to investigate the role of microbial inoculants in sugar beet production and their potential to replace chemical fertilizers and put forward the scientific hypothesis that microbial inoculants can increase soil nutrients and improve the soil microenvironment. A two-year field experiment was conducted: in 2022, treatments with different application rates of Bacillus subtilis and Trichoderma spp. inoculants were set up to screen the optimal inoculant and its dosage (M1); in 2023, based on this optimal inoculant (M1), treatments with reduced chemical fertilizer input were established to explore the mechanisms underlying the maintenance of sugar beet yield and quality. The results showed that the M1N2 (75 kg/ha fertilizer and 20% less nitrogen fertilizer) treatment significantly increased nitrogen, phosphorus, and potassium agronomic use efficiencies by 91.48%, 51.94%, and 53.50%, respectively, compared with the control (CK). Soil urease, catalase, and sucrase activities were significantly enhanced by 14.57%, 66.84%, and 222.46%, respectively. The treatment also significantly increased the relative abundance of beneficial bacterial genera such as JG30-KF-CM45 and KD4-96, while sugar beet yield was significantly increased by 5.53% relative to the CK. This study provides a theoretical basis for the application of microbial inoculants and the reduction in chemical fertilizers in sugar beet production.

Soil salinization poses significant threats to food security and ecosystem functions, while acid-modified biochar functions as an effective carbon-based material for the reclamation of saline–alkali soils. In this study, acid-modified biochars prepared using boric (BC), sulfuric (SC), hydrochloric (HC), acetic (AC), phosphoric (PC), and oxalic (OC) acids were analyzed. The ameliorative effects of acid-modified biochar on soda–saline–alkaline soils were evaluated through adsorption and pot experiments, with preliminary insights into its mechanism of action. The results indicated that the specific surface area and maximum adsorption capacities (Q_m) of conventional biochar and OC were 5.91, 35.39 m² g⁻¹ and 21.62, 41.00 mg g⁻¹, respectively. After the addition of conventional biochar, OC and SC in pot experiments, soil pH, (CO₃²⁻ + HCO₃⁻) content, and exchangeable sodium percentage (ESP) were significantly reduced. Compared to conventional biochar, SC increased the relative abundance of Bacillus, Adhaeribacter, and Preussia, while OC increased the relative abundance of Antarcticbacterium, Diezia, and Peziza. OC and SC maximally increased both the aboveground and belowground biomass of Medicago falcata L., while simultaneously reducing sodium content. This study demonstrated that biochar modified with SC and OC significantly reduced soda–saline–alkali stress. SC and OC exhibited greater potential in remediating soda–saline–alkali soils.