Water scarcity and rising fertilizer costs challenge the sustainable cultivation of medicinal and aromatic plants in arid regions. This study evaluated the interactive effects of irrigation intervals (21, 28, and 35 days) and potassium sources (potassium sulfate and feldspar) and rates on growth, yield, essential oil productivity, and nutrient status of fennel (Foeniculum vulgare Mill.) over two consecutive seasons in Middle Egypt. Extending irrigation intervals significantly increased soil electrical conductivity while reducing soil-available potassium, whereas soil pH, organic matter, and bulk density remained unaffected. Frequent irrigation (21 days) markedly enhanced vegetative growth, yield components, seed yield, and essential oil yield, producing up to 69.7 L ha⁻¹ oil compared with 50.5–52.0 L ha⁻¹ under 35-day intervals. Potassium fertilization significantly improved plant performance across all irrigation regimes, with potassium sulfate at 120 kg K2O ha⁻¹ consistently producing the highest plant height (≈173 cm), number of umbels (≈45 plant⁻¹), 1000-seed weight (≈13 g), seed yield, and oil yield. Potassium sulfate at 120 kg K2O ha⁻¹ consistently outperformed feldspar, though high-rate feldspar (572 kg K2O ha⁻¹) significantly improved performance over the control, indicating potential as a supplementary source. Extending irrigation to 28 days reduced water application by approximately 23% compared to 21-day intervals, with acceptable yield levels when combined with adequate potassium supply. Potassium application enhanced seed and herb N, P, and K concentrations and mitigated the adverse effects of prolonged irrigation intervals, particularly under moderate water stress (28 days). Significant irrigation × potassium interactions confirm that optimal potassium nutrition improved water-use efficiency and reproductive performance. Overall, integrating frequent or moderately extended irrigation with an adequate potassium supply—especially soluble potassium sulfate—offers an effective strategy to sustain fennel productivity and essential oil yield under water-limited conditions.

Aims: Saline sandy soils severely constrain sugar beet (Beta vulgaris L.) productivity due to low nutrient retention, high salinity, and micronutrient imbalances, particularly boron deficiency. Although humic substances, glauconite, and boron fertilization have individually or pairwise improved crop performance, no previous field study has evaluated their ternary, dose-optimized integration as a multifunctional soil–plant management strategy under saline sandy conditions. Methods: This study investigated, for the first time, the combined application of soil-applied humic acid (600 kg/ha), glauconite (1100 kg/ha), and graded foliar boric acid (0, 1900, and 3800 g/ha) to test the hypothesis that their complementary physicochemical and physiological mechanisms would generate synergistic improvements in soil quality, crop performance, and sugar productivity beyond additive effects. Field experiments were conducted over two consecutive growing seasons (2021–2022) in West Minya, Egypt, using a split-plot design. Results: The integrated high-dose treatment (HG3800) significantly enhanced leaf area index (by 75%), chlorophyll content (46–71%), and net photosynthetic rate (40–128%) relative to the control. Root yield increased by 27% (reaching 56.7 ton/ha), while sugar yield rose by up to 79% (11.5 ton/ha). Sucrose concentration reached 20.4%, with reduced impurity indices and improved extractable sugar percentage (up to 90%). Based on fermentable sugar yield, the HG3800 treatment corresponded to a substantial increase in theoretical bioethanol output potential per hectare. Concurrently, soil electrical conductivity declined by 24%, soil organic matter increased, and bulk density decreased, reflecting improved soil structure and salinity mitigation. Conclusions: The ternary, dose-optimized integration of humic acid, glauconite, and foliar boron represents a novel agronomic strategy that simultaneously enhances soil physicochemical properties, physiological efficiency, and fermentable sugar production. By directly linking yield gains to increased bioethanol feedstock potential, this approach offers a scalable and multifunctional pathway for sustainable bioenergy-oriented sugar beet production in salt-affected sandy soils.

Water scarcity is a critical constraint to sustainable agricultural production in arid and semi-arid regions. This study evaluated the effectiveness of subirrigation controlled drainage (SCD) systems in improving water use efficiency, soil conditions, and productivity of Egyptian clover (Trifolium alexandrinum L.) over two consecutive growing seasons (2022–2024). Three drainage treatments were investigated: subirrigation controlled drainage with water table depths of 0.4 m (SCD-0.4) and 0.8 m (SCD-0.8), and conventional free drainage at 1.2 m (SFD-1.2). The results demonstrated that SCD significantly reduced irrigation water requirements, achieving water savings of up to 27% under SCD-0.4 compared with conventional drainage. The shallow water table enhanced groundwater contribution to crop evapotranspiration, reaching over 40%, which improved soil moisture availability and reduced soil water depletion. Consequently, SCD-0.4 increased fresh and dry biomass yields by approximately 18% and significantly improved water productivity and irrigation water productivity. However, controlled drainage led to increased soil salinity due to reduced leaching, particularly in upper soil layers. Economic analysis revealed that SCD-0.4 achieved the highest net returns and water use profitability. Overall, controlled drainage at shallow depths represents an effective strategy to enhance water productivity, crop yield, and economic efficiency, although long-term salinity management must be considered for sustainable implementation.