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Mosa, W., Almutairi, K., Malusà , E., Ayoub, A., Abada, H., and Mohamed , A. H. (2026). "Synergistic effects of magnesium sulfate and compost on improving the productivity of date palm under drought stress," BioResources 21(3), 8275–8302.

Abstract

Drought is one of the most significant environmental stress factors negatively affecting fruit tree cultivation because they are highly water-dependent. Water shortage adversely affects the growth and development of fruit trees, leading to a severe reduction in productivity and fruit quality. In particular, drought harms photosynthesis, which is essential to produce carbohydrates. Therefore, developing mitigation strategies and effective water management is vital for maintaining fruit tree health and sustainability. This study was conducted to investigate the influence of adding soil compost individually and in combination with spraying of magnesium sulphate (MgSO4) on improving the soil fertility, productivity, and fruit quality of date palm cv. Barhi. The date trees were fertilized with 5 and 10 kg of compost, and then they were sprayed with 0.5, 0.75, and 1 % MgSO4 four times: starting from mid-February with one-month intervals between sprays, as compared to untreated trees as a control. The results revealed that combining soil-applied compost with foliar spraying of MgSO4 enhanced the productivity and fruit quality of date palm. The best results were obtained by adding 10 kg compost + 1% MgSO4, followed by 10 kg compost + 0.75% MgSO4 and 5 kg compost + 1%  MgSO4.


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Synergistic Effects of Magnesium Sulfate and Compost on Improving the Productivity of Date Palm Under Drought Stress

Walid F. A. Mosa  ,a,* Khalid F. Almutairi  ,b,* Eligio Malusà  ,c Ahmed Ayoub,d

Hesham S. Abada,e and Azza H. Mohamed f

Drought is one of the most significant environmental stress factors negatively affecting fruit tree cultivation because they are highly water-dependent. Water shortage adversely affects the growth and development of fruit trees, leading to a severe reduction in productivity and fruit quality. In particular, drought harms photosynthesis, which is essential to produce carbohydrates. Therefore, developing mitigation strategies and effective water management is vital for maintaining fruit tree health and sustainability. This study was conducted to investigate the influence of adding soil compost individually and in combination with spraying of magnesium sulphate (MgSO4) on improving the soil fertility, productivity, and fruit quality of date palm cv. Barhi. The date trees were fertilized with 5 and 10 kg of compost, and then they were sprayed with 0.5, 0.75, and 1 % MgSO4 four times: starting from mid-February with one-month intervals between sprays, as compared to untreated trees as a control. The results revealed that combining soil-applied compost with foliar spraying of MgSO4 enhanced the productivity and fruit quality of date palm. The best results were obtained by adding 10 kg compost + 1% MgSO4, followed by 10 kg compost + 0.75% MgSO4 and 5 kg compost + 1% MgSO4.

DOI: 10.15376/biores.21.3.8275-8302

Keywords: Organic fertilization; Productivity; Magnesium sulphate; Date palm

Contact information: a: Plant Production Department (Horticulture-Pomology), Faculty of Agriculture, Saba Basha, Alexandria University, Alexandria 21531, Egypt; b: Department of Plant Production, College of Food Science and Agriculture, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia; c: Council for Agricultural Research and Economics – Center for Viticulture and Enology, via Micca 35, 14100 Asti, Italy; d: Project Management Department, Arid Lands Cultivation Research Institute (ALCRI), City of Scientific Research and Technological Applications (SRTA-City), New Borg Al-Arab City, Egypt; e: Plant Production Department, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab City 21934, Egypt; f: Citrus Research and Education Center, University of Florida (IFAS), Lake Alfred, FL 33850, USA;

* Corresponding authors: [email protected]; [email protected]

INTRODUCTION

Dates are rich in essential components, including sugars, proteins, nutrients, fiber, antioxidants, and vitamins (Kamal-Eldin and Ghnimi 2018). Drought represents a critical abiotic stress that limits agricultural productivity across the world, impairing the growth, vitality, yield, and fruit quality of trees due to their substantial dependence on water availability (Šircelj et al. 2007; Almutairi et al. 2024). Water deficiency leads to a reduction in the photosynthesis process, which is a vital process for producing carbohydrates by converting sunlight into energy, ultimately minimizing the growth and fruit productivity (Wang et al. 2018; Roussos 2020). Various agricultural management practices can be employed to mitigate drought stress, including enhancing soil water retention capacity, increasing organic matter content, and improving soil fertility (Kılıç et al. 2024).

Organic fertilizers, particularly compost, are essential components of sustainable agriculture because they improve soil quality by promoting better soil structure and moisture retention, while increasing cation exchange capacity and the availability of essential nutrients. These effects are especially beneficial in sandy soils characterized by low organic matter content and poor nutrient retention. Moreover, the high organic matter content of compost stimulates microbial activity, increasing nutrient and mineral availability for plants and thereby enhancing crop growth and productivity (Diacono and Montemurro 2010; Wang et al. 2014). Soil organic matter also plays a vital role in soil fertility by improving the soil’s physical, chemical, and biological characteristics, which contribute to higher crop yields and better water infiltration and retention, ultimately increasing plant tolerance to drought conditions (Gokcen and Kuzucu 2023; Kuzucu and Gökçen 2024).

Compost is also effective in optimizing the structural, chemical, and biological traits of soils (Lakhdar et al. 2009), and raising the pH of acidic soils (Ch’Ng et al. 2014). Roghanian et al. (2012) demonstrated that compost amendment stimulates root system development and enhances nutrient acquisition, thereby promoting greater vegetative growth, as reflected in increased stem elongation and plant dry biomass. Furthermore, compost decomposition facilitates nutrient mineralization and improves nutrient solubility, resulting in enhanced soil availability of phosphorus and potassium. Incorporating compost into cultivation soil can enhance crop productivity and increase soil organic matter content (Luo et al. 2017). The application of compost is generally recognized to improve soil water retention and increase moisture availability, although its impact can vary widely depending on factors such as soil texture, compost properties, and environmental conditions (Sax et al. 2017). Compost use can also influence the soil microbiome, promoting greater microbial diversity (Thompson et al. 2019). Compost application contributes to the improvement of soil physicochemical quality by increasing water retention, enhancing cation exchange capacity, improving nutrient bioavailability, and promoting greater soil structural integrity and stability (Hasini et al. 2020; Manirakiza and Şeker, 2020). These improvements promote better nutrient uptake and transport within plants by improving the physical, chemical, and biological characteristics of the soil (Gondek et al. 2020). In saline soils, compost mitigates the adverse effects of salinity through enhanced nutrient availability and water absorption (Castiglione et al. 2021). Consequently, compost application contributes to improved plant nutritional status and overall growth performance (Ud Din et al. 2023). Compost serves as a gradual nutrient supplier, fostering enhanced plant growth and agricultural productivity while limiting nitrate leaching into groundwater systems. Consequently, its use can alleviate one of the major environmental challenges associated with intensive synthetic fertilizer application (Jatav et al. 2025).

Magnesium (Mg) is a vital macronutrient that performs indispensable functions in plant growth and development. As the central atom of the chlorophyll molecule, it is fundamental to photosynthetic activity. Moreover, Mg serves as a cofactor for numerous enzymatic reactions, facilitates carbohydrate metabolism and transport, supports cellular homeostasis, and plays a critical role in protein biosynthesis and cell division (Verbruggen and Hermans 2013). Mg also enhances plant tolerance to biotic and abiotic stresses, particularly drought and salinity, which can explain why it has become increasingly important in modern agricultural production (Boaretto et al. 2020). Furthermore, Mg transporters contribute to proper pollen development, male fertility, and fruit quality (Tian et al. 2021; Xu et al. 2021). Adequate Mg nutrition enhances fruit quality traits, including flavor, soluble solids, sugar content, and vitamin C concentration, as reported in grapefruit and other citrus crops (Papadakis et al. 2023). On the other hand, the deficiency of Mg disrupts nutrient uptake and utilization, reduces photosynthesis, protein synthesis, and carbohydrate transport, and impairs various metabolic processes, leading to reduced plant growth, biomass accumulation, yield, and fruit quality (Ling LiLi et al. 2009). In citrus species, Mg deficiency alters nutrient distribution, decreases CO₂ assimilation, impairs cell metabolism and carbohydrate partitioning, and can reduce iron accumulation in roots, ultimately lowering fruit yield and quality (Huang et al. 2019; Jia et al. 2021). Similar adverse effects have been reported in date palm and grapevine, where Mg deficiency negatively affects plant productivity and fruit quality (Anli et al. 2023; Copp et al. 2025).

Sulfur (S) is a macronutrient required for plant growth and development (Marschner 2012; Kopriva et al. 2019) and is also known to enhance crop quality (Kopriva et al. 2015) as well as improve plant responses to abiotic stresses (Santisree et al. 2019). A sufficient supply of S throughout all stages of plant growth is essential for optimal crop performance (Edis and Norton 2012). The physiological importance of S is attributed to its role as a fundamental constituent of S-containing amino acids, including methionine, cysteine, and cystine, as well as sulpholipids and various coenzymatic compounds that are essential for cellular metabolism and plant development. Through these functions, S contributes to protein biosynthesis, chlorophyll and B-group vitamin formation, carbohydrate metabolism, and the regulation of plant growth and metabolic activities via its interaction with proteolytic enzyme systems (Njira and Nabwami 2015). S deficiency reduces root hydraulic conductivity, a response that may be involved in root-to-shoot signaling of nutrient deprivation (Mitchell 2021).

Therefore, this study was designed to examine the combined effects of soil-applied compost and foliar spraying with magnesium sulfate on the growth and productivity of Barhi date palm, thereby enhancing yield and the fruit’s physical and chemical properties.

EXPERIMENTAL

The study was conducted during the 2024 and 2025 seasons on 12-year-old Barhi date palm trees, which were originally planted in the Wadi El-Natroun region of El-Behera Governorate, Egypt. The trees were cultivated in sandy soil, spaced 7 × 7 m2 apart, and irrigated using a drip irrigation system. Sixty date palm trees, as similar as possible in their vigor, were chosen for this study, where 5 trees (5 replicates) were selected for each treatment. The treatments were organized using a Split Plot Design, with soil compost application serving as the main factor and foliar spraying of MgSO4 as the submain factor, compared to unsprayed trees used as the control. The trees were fertilized with 5 and 10 kg of compost at the start of February 2024. Subsequently, the date palms were sprayed with 0.5, 0.750, and 1 % MgSO4, four times, starting from mid-February with one-month intervals between sprays, compared to untreated trees as a control. The analysis of the experimental soil is shown in Table 1.

Table 1. Physiochemical Soil Characteristics

Physiochemical Soil Characteristics

Table 2. Physiochemical Soil Characteristics After the Addition of Compost

Physiochemical Soil Characteristics After the Addition of Compost

Table 3. Meteorological Data of the Experimental Area During the Two Study Seasons

Meteorological Data of the Experimental Area During the Two Study Seasons

The effect of the treatments mentioned above was examined by studying their effects on the following parameters.

Palm Yield

At harvest, palm yield was measured in kg, and the total yield per hectare was calculated by multiplying the number of palms by their average yield.

Fruit Quality

In September of 2024 and 2025, at the time of fruit ripening, 40 fruits from each tree (replicate) were harvested and immediately transported to the laboratory for analysis of their physical and chemical characteristics.

Fruit Physical Characteristics

The average fruit weight (g) was obtained by calculating the mean weight of 40 individual fruits. Flesh weight (g) and seed weight (g) were measured, and the flesh-to-fruit ratio was determined. Fruit length and width (cm) were measured using a digital vernier caliper, while fruit firmness (lb/in²) was evaluated with a Magness–Taylor pressure tester (model FT 02, range 0 to 2 lb, Alfonsine, Italy).

Fruit Chemical Characteristics

The total soluble solids percentage in fresh fruits was measured using a hand-held refractometer. Fruit acidity, expressed as a percentage of malic acid, was determined by titrating fruit juice with 0.1 N sodium hydroxide, using phenolphthalein as an indicator (AOAC 2005). Total sugar content (%) was quantified using the phenol–sulfuric acid method, while reducing sugars were measured colorimetrically following Nelson’s procedure (Nielsen 2010). Non-reducing sugar content was calculated by subtracting reducing sugars from total sugars. Ascorbic acid (vitamin C) concentration in the juice was determined via titration with 2,6-dichloro phenol-indophenol (Nielsen 2017). Total chlorophyll content was estimated according to Richardson et al. (2002), with absorbance measured at 650 nm using a spectrophotometer (Jiangxi Dongling Technology Company, Qingshanhu District, Nanchang City, Jiangxi Province, China). Similarly, carotene content was determined following the method of Aquino et al. (2018), with absorbance recorded at 440 nm.

Statistical Analysis

The statistical analysis was performed using a split-plot design in CoHort Software version 6.311 (Pacific Grove, CA, USA). Treatment means were compared using the least significant difference (LSD₀.₀₅) test as described by Snedecor and Cochran (1990).

RESULTS

Table 4 shows that adding compost to the soil enhanced bunch weight, palm tree yield, and yield per hectare. The improvement became more pronounced when combined with foliar spraying of MgSO4 compared to the control. The highest performance was achieved with the combined treatment of 10 kg compost and 1% MgSO4, surpassing all other treatments. Furthermore, higher foliar doses of MgSO4 were particularly effective in boosting bunch weight and overall productivity of date palm trees in both seasons.

The data in Table 5 demonstrate that when date palm trees were fertilized with compost combined with the spraying of MgSO4, they significantly improved the fruit weight, flesh weight, and flesh fruit ratio compared to untreated trees. Moreover, the soil addition of 10 kg from compost mixed with the spraying of 1% MgSO4, followed by 0.75% MgSO4, notably improved these physical fruit characteristics over the addition of the compost or spraying MgSO4 individually. Additionally, adding 5 kg of compost to the soil and then spraying the date trees with 1% MgSO4 also improved the fruit and flesh weights and flesh-fruit ratio.

Table 4. Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on Date Palm cv. Barhi During 2024 and 2025 Seasons

Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on Date Palm cv. Barhi During 2024 and 2025 Seasons

Table 5. Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on Date Palm cv. Barhi During 2024 and 2025 Seasons

Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on Date Palm cv. Barhi During 2024 and 2025 Seasons

The addition of 6 or 10 kg from compost, combined with spraying the date trees with MgSO4 improved the fruit length and fruit diameter compared to untreated trees (Table 6). The fruit diameter and fruit firmness significantly improved by the addition of 10 kg compost combined with the spraying of 1% MgSO4 compared to the other applied treatments. The differences between the effects of 10 kg compost combined with the foliar spraying of 1 or 0.75% MgSO4 and 5 kg compost + 1% MgSO4 were insignificant. Moreover, fruit length, diameter, and firmness were improved with the spraying of 1% MgSO4 more than 0.75 or 0.5% MgSO4 in the two seasons.

Table 6. Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on Date Palm cv. Barhi Fruit Quality During 2024 and 2025 Seasons

Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on Date Palm cv. Barhi Fruit Quality During 2024 and 2025 Seasons

Across the two seasons, trees treated with compost in combination with MgSO4 spraying exhibited considerably higher levels of carotene, vitamin C, and chlorophyll in fruits than untreated trees (Table 7). Additionally, the fruit content of carotene and vitamin C was clearly increased by the addition of 10 kg of compost combined with 1% MgSO4 relative to the applied treatments. For chlorophyll content, the highest significant values were obtained by the combined application of 10 kg compost mixed with the spraying of 1% and then with 0.75% MgSO4. The high-sprayed doses from MgSO4 were more efficient in their influence in improving the fruit content from these chemical fruit characteristics rather than the trees that were not sprayed.

Table 7. Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on the Fruit Composition from Carotene, Chlorophyll, and Vitamin C in Date Palm cv. Barhi During 2024 and 2025 Seasons

Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on the Fruit Composition from Carotene, Chlorophyll, and Vitamin C in Date Palm cv. Barhi During 2024 and 2025 Seasons The fruit content from total soluble solids and also TSS/Acidity ratio were significantly increased via the addition of 10 kg compost combined with the spraying of 1% MgSO4. Meanwhile, this treatment markedly reduced the fruit content from acidity percentages compared to the control (Table 8). In both seasons, the application of 10 kg compost with either 0.75% or 0.5% MgSO4 sprays, as well as 5 kg compost + 1% MgSO4, significantly improved fruit TSS% and the TSS/Acidity ratio, while simultaneously lowering fruit acidity compared with other treatments.

Table 8. Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on the Fruit Content from TSS%, Acidity%, and TSS/Acidity in Date Palm cv. Barhi During 2024 and 2025 Seasons

Effect of the Soil Addition of Compost and the Spraying of Magnesium Sulphate on the Fruit Content from TSS%, Acidity%, and TSS/Acidity in Date Palm cv. Barhi During 2024 and 2025 Seasons

Table 9. Effect of the Compost Soil Addition and Magnesium Sulphate Spraying on Fruit Content from Total, Reduced, and Non-reduced Sugars in Date Palm cv. Barhi During 2024 and 2025 Seasons

Effect of the Compost Soil Addition and Magnesium Sulphate Spraying on Fruit Content from Total, Reduced, and Non-reduced Sugars in Date Palm cv. Barhi During 2024 and 2025 Seasons

The results demonstrated that the application of compost and foliar spraying with MgSO₄ significantly increased both total and reducing sugar contents during the 2024 and 2025 seasons (Table 9). A progressive increase in sugar accumulation was observed as compost amounts increased from 0 to 10 kg and MgSO₄ concentrations rose from 0 to 1%. The maximum total sugar contents (32.6 and 33.2%) and reducing sugar contents (26.2 and 26.8%) were achieved with the combined treatment of 10 kg compost and 1% MgSO₄, whereas untreated plants exhibited the lowest values. Conversely, non-reducing sugars were not significantly influenced by the treatments, as no significant differences were detected among the means. The positive effect of compost and MgSO₄ may be associated with enhanced nutrient availability and improved photosynthetic efficiency, which promote carbohydrate biosynthesis and their subsequent accumulation in fruit tree tissues.

DISCUSSION

The results clearly show that adding compost to the soil improved date palm productivity and fruit quality. These results were explained by many authors who reported that the application of compost improves soil physical, chemical, and biological properties by acting as both a nutrient source and a soil conditioner. Besides, compost increases soil organic matter, dissolved organic carbon, humic substances, nutrient retention and availability, cation exchange capacity, and water-holding capacity, thereby enhancing root development and plant productivity (Lehmann et al. 2011; Marschner 2011). By stimulating beneficial microbial and rhizospheric communities, compost improves soil health and functionality. Its incorporation enhances soil structure, increases pore space and water movement, lowers bulk density, and improves hydraulic properties and irrigation efficiency. These effects collectively promote more favorable soil moisture conditions and enhance plant resilience to environmental stresses such as water deficit and salinity (Schulz et al. 2014). Furthermore, compost contributes to soil carbon sequestration and climate change mitigation, while reducing production costs and the environmental impacts of agricultural practices through lower requirements for synthetic fertilizers, pesticides, and fuel inputs (Scotti et al. 2016).

Bernal et al. (2017) and Wang et al. (2022) investigated the effects of compost application on soil fertility, crop performance, and environmental impacts, reporting that compost improves soil physical structure, increases nutrient accessibility, and reduces greenhouse gas emissions relative to conventional fertilization systems. Compost improves efficiency of nutrient use, helps preserve soil organic carbon, and enhances soil carbon sequestration, underscoring the importance of sustainable soil management practices for maintaining resilient agricultural systems (Pergola et al. 2018; Zhao et al. 2020). The application of compost as a soil amendment enhances soil fertility, promotes carbon sequestration, and improves the physical, chemical, and biological characteristics of soil (Sultana et al. 2021). In this context, composting aligns effectively with the circular economy concept by promoting nutrient recycling and reducing dependence on synthetic fertilizers. Moreover, it supports sustainable agricultural systems and plays a vital role in ensuring long-term food security (Ajaweed et al. 2022). Consequently, compost application enhances crop productivity and tolerance to abiotic stresses, reduces soil erosion, nutrient losses, and dependence on synthetic fertilizers and excessive irrigation, while contributing to improved water quality, reduced environmental pollution, and healthier agroecosystems (Ho et al. 2022; Mosa et al. 2024). In addition, compost supplies essential macro- and micronutrients, including nitrogen, phosphorus, potassium, iron, copper, zinc, and boron, enhancing nutrient uptake, photosynthetic activity, plant growth, and productivity (Otaiku 2022). It helps maintain soil pH within a favorable range for crop production, promotes nutrient cycling through increased microbial activity, and serves as a slow-release nutrient source that improves long-term soil fertility and nitrogen use efficiency while reducing nutrient losses (Aouass and Kenny 2023; Bremaghani 2024). The incorporation of compost into mango orchards was found to positively influence tree growth and productivity, resulting in enhanced vegetative development, greater fruit retention, increased yield, improved physical and biochemical fruit characteristics, and a more favorable leaf mineral composition compared with non-amended controls (Mosa et al. 2024).

The beneficial effects of magnesium (Mg) on yield and on the physical and chemical attributes of fruit are largely explained by its fundamental involvement in a wide range of physiological and biochemical processes that underpin plant growth, nutrient efficiency, and tolerance to environmental stresses. Additionally, Mg is an essential macronutrient and a structural component of the chlorophyll molecule, where it contributes to chlorophyll synthesis and stability, enhances photosynthetic efficiency, and promotes the production of assimilates (Cakmak 2013). Mg also regulates potassium transport across cell membranes, stimulates root activity, and improves nutrient absorption, helping to maintain osmotic balance, stomatal conductance, and enzymatic functions (Hermans et al. 2013; Assunção et al. 2022). Additionally, Mg also activates more than 300 enzymes involved in photosynthesis, respiration, nucleic acid and protein synthesis, ATP formation and utilization, and other metabolic pathways essential for plant development (Farhat et al. 2016; Kleczkowski and Igamberdiev 2021). Mg plays a vital role in carbohydrate production, translocation, and fruit quality by enhancing photosynthesis, facilitating assimilation transport from source leaves to sink organs, and promoting sugar accumulation in horticultural crops such as citrus and apple (Li et al. 2017; Liu et al. 2022). Adequate Mg nutrition improves the uptake and balance of essential nutrients, including nitrogen, phosphorus, potassium, and calcium, thereby enhancing plant growth, yield, and fruit quality (Ye et al. 2019). Furthermore, sufficient Mg levels contribute to soil fertility and rhizosphere health by maintaining nutrient equilibrium, improving nutrient availability, supporting optimal rhizosphere pH, and stimulating beneficial microbial populations in the rhizosphere, particularly mycorrhizal fungi and plant growth-promoting rhizobacteria (Wang et al. 2020; Hou et al. 2021). Such interactions enhance nutrient absorption, boost tolerance to abiotic stress, and support increased crop productivity alongside long-term agricultural sustainability (Yang et al. 2021). In apple cv. Red Fuji, Mg application was shown to improve nitrogen utilization, photosynthesis, anthocyanin biosynthesis, fruit size, fruit weight, and overall productivity (Tian et al. 2023). Conversely, Mg deficiency impairs assimilate transport, causes carbohydrate accumulation in leaves, reduces photosynthetic performance, and ultimately decreases crop productivity and fruit quality. Mg is readily mobile in soil and easily lost through leaching, particularly in sandy soils and systems with heavy fertilization; therefore, maintaining adequate Mg levels is vital for maximizing plant development, yield, and fruit quality (Senbayram et al. 2015).

Sulphur (S) is an essential nutrient that supports plant growth and productivity through its role in the synthesis of proteins, enzymes, vitamins, chlorophyll, and photosynthetic membrane sulfolipids, thereby enhancing photosynthesis, carbohydrate production, and overall plant development (Brosnan and Brosnan 2006; Maathuis 2009). S supplementation has been shown to promote cellular division and expansion processes, thereby contributing to the development and enlargement of plant organs and enhancing overall crop growth and productivity (Patel et al. 2019), and improve nutrient acquisition and utilization efficiency (Zenda et al. 2021). Additionally, it also participates in the biosynthesis and signaling of phytohormones, such as ethylene, hydrogen sulfide, and polyamines, which enhance plant defense mechanisms and improve tolerance to biotic and abiotic stresses (Samanta et al. 2020; Jahan et al. 2021). S is a significant growth-limiting nutrient and influences the uptake of other nutrients such as N, P, K, molybdenum, zinc, iron, selenium, and boron (Astolfi et al. 2021). Besides, it is essential for plant growth and productivity due to its critical role in nutrient acquisition and metabolism. It enhances nitrogen uptake and assimilation by facilitating the incorporation of nitrogen into amino acids and proteins, thereby improving nutrient use efficiency and supporting higher crop yields (Dawar et al. 2023). Furthermore, S plays a vital role in chlorophyll biosynthesis, facilitating efficient light energy capture for photosynthesis and supporting plant growth. It is also an essential constituent of numerous enzymes and coenzymes involved in key metabolic processes, particularly nitrogen assimilation, which is fundamental for amino acid and protein synthesis. Consequently, adequate S nutrition enhances growth, development, and productivity, thereby increasing fruit weight and yield, whereas S deficiency impairs chlorophyll formation, reduces photosynthetic efficiency, and ultimately limits crop productivity (Narayan et al. 2023).

CONCLUSIONS

  1. The combined soil application of compost and foliar spraying of MgSO₄, either individually or in combination, significantly improved fruit yield and enhanced physical and chemical fruit quality compared with untreated trees under drought stress conditions.
  2. The most effective treatment was the application of 10 kg compost combined with 1% MgSO₄, followed by 10 kg compost with 0.75% MgSO₄, and then 5 kg compost with 1% MgSO₄, all of which showed superior yield and quality performance.
  3. The observed improvements in yield and fruit quality may be associated with the use of organic amendments and magnesium supplementation, which are commonly reported to support plant productivity under stress conditions.
  4. Overall, compost application in combination with MgSO₄ foliar spraying appears to be a promising agronomic practice for improving date palm productivity and fruit quality under drought stress; however, further studies are needed to confirm the underlying effects on soil physicochemical properties.

Funding

This research was funded by Ongoing Research Funding program, (ORF-2026-561), King Saud University, Riyadh, Saudi Arabia.

ACKNOWLEDGMENTS

The authors extend their appreciation to Ongoing Research Funding program, (ORF-2026-561), King Saud University, Riyadh, Saudi Arabia.

Data Availability Statement

All the required data are included in the manuscript.

Conflicts of Interest

The authors declare no conflicts of interest.

REFERENCES CITED

Ajaweed, A. N., Hassan, F. M., and Hyder, N. H. (2022). “Evaluation of physio-chemical characteristics of bio fertilizer produced from organic solid waste using composting bins,” Sustainability 14(8), article 4738.

Almutairi, K. F., Górnik, K., El Adly, R. M., and Mosa, W. F. (2024). “Pear performance as affected by the application of some nano fertilizers in combination with biochar as a biostimulant under drought conditions,” BioResources 19(4), 9131-9157. https://doi.org/10.15376/biores.19.4.9131-9157

Anli, M., Alahyane, A., Mohamed, A. B., Boutasknit, A., Ben-Laouane, R., Rahou, Y. A., El Modafar, C., and Meddich, A. (2023). “Effectiveness of green compost mixed with phosphate sludge on the defense performance of date palm in soil with Fusarium oxysporum f. sp. albedinis infestation,” Eur. J. Plant Pathol. 165(2), 287-303.

AOAC (2005). Official Methods of Analysis, 18th Ed., W. Hortwitz, and G. W. Latimer (eds.), Association of Official Analytical Chemists-International AOAC, Gaithersburg, MD, USA, pp. 20877-2417.

Aouass, K., and Kenny, L. (2023). “Nitrogen use efficiency and yield of broccoli crop fertilized with compost and synthetic fertilizer in arid region of Morocco,” Bulg. J. Agric. Sci., 29(2), 277–284.

Aquino, C. F., Salomão, L. C. C., Pinheiro-Sant’ana, H. M., Ribeiro, S. M. R., Siqueira, D. L. D., and Cecon, P. R. (2018). “Carotenoids in the pulp and peel of bananas from 15 cultivars in two ripening stages,” Revista Ceres 65(3), 217-226. https://doi.org/10.1590/0034-737X201865030001

Assunção, A. G., Cakmak, I., Clemens, S., González-Guerrero, M., Nawrocki, A., and Thomine, S. (2022). “Micronutrient homeostasis in plants for more sustainable agriculture and healthier human nutrition,” J. Exp. Bot. 73(6), 1789-1799. https://doi.org/10.1093/jxb/erac014

Astolfi, S., Celletti, S., Vigani, G., Mimmo, T., and Cesco, S. (2021). “Interaction between sulfur and iron in plants,” Front. Plant Sci. 12, article 670308. https://doi.org/10.3389/fpls.2021.670308

Bernal, M. P., Sommer, S. G., Chadwick, D., Qing, C., Guoxue, L., and Michel Jr, F. C. (2017). “Current approaches and future trends in compost quality criteria for agronomic, environmental, and human health benefits,” Adv. Agron. 144, 143-233.

Boaretto, R. M., Hippler, F. W., Ferreira, G. A., Azevedo, R. A., Quaggio, J. A., and Mattos, Jr, D. (2020). “The possible role of extra magnesium and nitrogen supply to alleviate stress caused by high irradiation and temperature in lemon trees,” Plant Soil 457(1), 57-70. https://doi.org/10.1007/s11104-020-04597-y

Bremaghani, A. (2024). “Utilization of organic waste in compost fertilizer production: Implications for sustainable agriculture and nutrient management,” Law Econ. 18(2), 86-98. https://journals.ristek.or.id/index.php/LE/article/view/87

Brosnan, J. T., and Brosnan, M. E. (2006). “The sulfur-containing amino acids: An overview,” J. Nutr. 136(6), 1636S-1640S. https://doi.org/10.1093/jn/136.6.1636S

Cakmak, I. (2013). “Magnesium in crop production, food quality and human health,” Plant Soil 368(1), 1-4. https://doi.org/10. 1007/s11104-013-1781-2

Castiglione, S., Oliva, G., Vigliotta, G., Novello, G., Gamalero, E., Lingua, G., Cicatelli, A., and Guarino, F. (2021). “Effects of compost amendment on glycophyte and halophyte crops grown on saline soils: Isolation and characterization of rhizobacteria with plant growth promoting features and high salt resistance,” Appl. Sci. 11(5), article 2125. https://doi.org/10.3390/app11052125

Ch’Ng, H. Y., Ahmed, O. H., and Majid, N. M. A. (2014). “Improving phosphorus availability in an acid soil using organic amendments produced from agroindustrial wastes,” Sci. World J. 2014, article 506356. https://doi.org/10.1155/2014/506356

Copp, K. L., Steffen, L. M., Yi, S.-Y., Lutsey, P. L., Rebholz, C. M., and Rooney, M. R. (2025). “Magnesium-rich diet score is inversely associated with incident cardiovascular disease: The Atherosclerosis Risk in Communities (ARIC) study,” Eur. J. Prev. Cardiol. 32(5), 386-393. https://doi.org/10.1093/eurjpc/zwae251

Dawar, R., Karan, S., Bhardwaj, S., Meena, D. K., Padhan, S. R., Reddy, K. S., and Bana, R. S. (2023). “Role of sulphur fertilization in legume crops: A comprehensive review,” Int. J. Plant Sci. 35, 718-727. https://doi.org/10.9734/IJPSS/2023/v35i214033

Diacono, M., and Montemurro, F. (2010). “Long-term effects of organic amendments on soil fertility,” Agron. Sustain. Dev. 30, 401-422. https://doi.org/10.1007/978-94-007-0394-0_34

Edis, R., and Norton, R. (2012). “Sulphur nutrition and fluid fertilisers,” Victorian Liquid Fertiliser Forum., p. 4. Available online: http://www.ipni.net/ (accessed on 12 February 2020).

Farhat, N., Elkhouni, A., Zorrig, W., Smaoui, A., Abdelly, C., and Rabhi, M. (2016). “Effects of magnesium deficiency on photosynthesis and carbohydrate partitioning,” Acta Physiol. Plant. 38(6), article 145. https://doi.org/10.1007/s11738-016-2165-z

Gokcen, I. S., and Kuzucu, M. (2023). “Soil quality and fertility in vineyards of Kilis province of Turkey, the northwest of “fertile crescent,” Emir. J. Food Agric. 35, 657-665. https://doi.org/10.9755/ejfa.2023.v35.i7.3116

Gondek, M., Weindorf, D. C., Thiel, C., and Kleinheinz, G. (2020). “Soluble salts in compost and their effects on soil and plants: A review,” Compost Sci. Util. 28(2), 59-75. https://doi.org/10.1080/1065657X.2020.1772906

Hasini, S. E., De Nobili, M., El Azzouzi, M., Azim, K., Douaik, A., Laghrour, M., El Idrissi, Y., El Alaoui El Belghiti, M., and Zouahri, A. (2020). “The influence of compost humic acid quality and its ability to alleviate soil salinity stress,” Int. J. Recycl. Org. Waste Agric. 9(1), 21-31. https://doi.org/10.30486/ijrowa.2020.671213

Hermans, C., Conn, S. J., Chen, J., Xiao, Q., and Verbruggen, N. (2013). “An update on magnesium homeostasis mechanisms in plants,” Metallomics 5(9), 1170-1183. https://doi.org/10.1039/c3mt20223b

Ho, T. T. K., Le, T. H., Tran, C.-S., Nguyen, P.-T., Vo, T.-D.-H., Thai, V.-N., and Bui, X.-T. (2022). “Compost to improve sustainable soil cultivation and crop productivity. Case Study,” Chem. Environ. Eng. 6, article 100211. https://doi.org/10.1016/j.cscee.2022.100211

Hou, J., Cheng, X., Li, J., and Dong, Y. (2021). “Magnesium and nitrogen drive soil bacterial community structure under long-term apple orchard cultivation systems,” Appl. Soil Ecol. 167, article 104103. https://doi.org/10.1016/j.apsoil.2021.104103

Huang, J.-H., Xu, J., Ye, X., Luo, T.-Y., Ren, L.-H., Fan, G.-C., Qi, Y.-P., Li, Q., Ferrarezi, R. S., and Chen, L.-S. (2019). “Magnesium deficiency affects secondary lignification of the vascular system in Citrus sinensis seedlings,” Trees 33(1), 171-182. https://doi.org/10.1007/s00468-018-1766-0

Jahan, B., Rasheed, F., Sehar, Z., Fatma, M., Iqbal, N., Masood, A., … and Khan, N. A. (2021). “Coordinated role of nitric oxide, ethylene, nitrogen, and sulfur in plant salt stress tolerance,” Stresses 1(3), 181-199. https://doi.org/10.3390/stresses1030014

Jatav, H. S., Rajput, V. D., Raza, T., and Maurya, P. (2025). “Mitigation strategies to reduce the climate change impact in agriculture,” J. Innov. Solut. Eco-Environ. Sustain. 1(1), 13493-13493. https://doi.org/10.46991/JISEES.2025.01.1.13493

Jia, Y., Xu, H., Wang, Y., Ye, X., Lai, N., Huang, Z., Yang, L., Li, Y., Chen, L.-S., and Guo, J. (2021). “Differences in morphological and physiological features of citrus seedlings are related to Mg transport from the parent to branch organs,” BMC Plant Biol. 21(1), article 239.  https://doi.org/10.1186/s12870-021-03028-z

Kamal-Eldin, A., and Ghnimi, S. (2018). “Classification of date fruit (Phoenix dactylifera, L.) based on chemometric analysis with multivariate approach,” J. Food Meas. Charact. 12(2), 1020-1027. https://doi.org/10.1007/s11694-018-9717-4

Kılıç, M., Gündoğan, R., and Guenal, H. (2024). “An illustration of a sustainable agricultural land suitability assessment system with a land degradation sensitivity,” Environ. Dev. Sustain. 26(3), article p6085.

https://doi.org/10.1007/s10668-023-02951-5

Kleczkowski, L. A., and Igamberdiev, A. U. (2021). “Magnesium signaling in plants,” Int. J. Mol. Sci. 22(3), article 1159. https://doi.org/10.3390/ijms22031159

Kopriva, S., Malagoli, M., and Takahashi, H. (2019). “Sulfur nutrition: Impacts on plant development, metabolism, and stress responses,” J. Exp. Bot. 70(16), 4069-4073. https://doi.org/10.1093/jxb/erz319

Kopriva, S., Calderwood, A., Weckopp, S. C., and Koprivova, A. (2015). “Plant sulphur and big data,” Plant Sci. 241, 1-10. DOI: 10.1016/j.plantsci.2015.09.014

Kuzucu, M., and Gökçen, I. S. (2024). “Micro-catchment rainwater harvesting technology in conservation agriculture and plant production,” Bangladesh J. Bot. 53(1), 9-16. https://doi.org/10.3329/bjb.v53i1.72114

Lakhdar, A., Rabhi, M., Ghnaya, T., Montemurro, F., Jedidi, N., and Abdelly, C. (2009). “Effectiveness of compost use in salt-affected soil,” J. Hazard. Mater. 171(1-3), 29-37. https://doi.org/10.1016/j.jhazmat.2009.05.132

Lehmann, J., Rillig, M. C., Thies, J., Masiello, C. A., Hockaday, W. C., and Crowley, D. (2011). “Biochar effects on soil biota–a review,” Soil Biol. Biochem. 43(9), 1812-1836. https://doi.org/10.1016/j.soilbio.2011.04.02

Li, C.-P., Qi, Y.-P., Zhang, J., Yang, L.-T., Wang, D.-H., Ye, X., Lai, N.-W., Tan, L.-L., Lin, D., and Chen, L.-S. (2017). “Magnesium-deficiency-induced alterations of gas exchange, major metabolites and key enzymes differ among roots, and lower and upper leaves of Citrus sinensis seedlings,” Tree Physiol. 37(11), 1564-1581. https://doi.org/10.1093/treephys/tpx067

Ling, L.-L., Peng, L.-Z., Cao, L., Jiang, C.-L., Chun, C.-P., Zhang, G.-Y., and Wang, Z.-X. (2009). “Effect of magnesium deficiency on photosynthesis characteristic of Beibei 447 Jinchen orange,” J. Fruit Sci. 26, 275-280. DOI: 10.1007/s11738-016-2165-z

Liu, X., Hu, C., Liu, X., Riaz, M., Liu, Y., Dong, Z., Tan, Q., Sun, X., Wu, S., and Tan, Z. (2022). “Effect of magnesium application on the fruit coloration and sugar accumulation of navel orange (Citrus sinensis Osb.),” Sci. Hortic. 304, article 111282. https://doi.org/10.1016/j.scienta.2022.111282

Luo, X., Liu, G., Xia, Y., Chen, L., Jiang, Z., Zheng, H., and Wang, Z. (2017). “Use of biochar-compost to improve properties and productivity of the degraded coastal soil in the Yellow River Delta, China,” J. Soils Sediments 17(3), 780-789. https://doi.org/10.1007/s11368-016-1361-1.

Maathuis, F. J. (2009). “Physiological functions of mineral macronutrients,” Curr. Opin. Plant Biol. 12(3), 250-258. DOI 10.1016/j.pbi.2009.04.003

Manirakiza, N., and Şeker, C. (2020). “Effects of compost and biochar amendments on soil fertility and crop growth in a calcareous soil,” J. Plant Nutr. 43(20), 3002-3019. https://doi.org/10.1080/01904167.2020.1806307

Marschner, H. (Ed.) (2011). “Marschner’s mineral nutrition of higher plants,” Academic press.

Marschner, P. (2012). Mineral Nutrition of Higher Plants, 3rd Ed.. Elsevier, New York, NY, USA.

Mitchell, S. C. (2021). “Nutrition and sulfur,” in: Advances in Food and Nutrition Research, Vol. 96. Academic Press, Jan 1. p. 123–174. https://doi.org/10.1016/bs.afnr.2021.02.014.

Mosa, W. F., Al-Saif, A. M., Sas-Paszt, L., Górnik, K., and Eladly, R. M. (2024). “Effect of the combined application of compost with the spraying of some nano fertilizers on the performance of mango,” Sustainability 16, article 10239. https://doi.org/10.3390/su162310239

Narayan, O. P., Kumar, P., Yadav, B., Dua, M., and Johri, A. K. (2023). “Sulfur nutrition and its role in plant growth and development,” Plant Signal. Behav. 18(1), article 2030082. https://doi.org/10.1080/15592324.2022.2030082

Nielsen, S. S. (2010). “Phenol-sulfuric acid method for total carbohydrates,” in: Food Analysis Laboratory Manual. Food Science Texts Series, S. S. Nielsen (Ed.), Springer, Boston, MA, USA, pp. 47-53. https://doi.org/10.1007/978-1-4419-1463-7_6

Nielsen, S. S. (2017). “Vitamin C determination by indophenol method,” in: I. F. A. L. Manual., Food Science Text Series. Springer, Cham., pp. 143-146. https://doi.org/10.1007/978-3-319-44127-6_15 In.

Njira, K. O., and Nabwami, J. (2015). “A review of effects of nutrient elements on crop quality,” Afr. J. Food Agric. Nutr. Dev. 15(1), article 9777.

Otaiku, A. A. (2022). “Biofertilizer impacts| Cassava (Manihot Esculenta Crantz) cultivation crop yield and regenerative agriculture,” Global J. Agric. Res. 10(1), 1-90. https://doi.org/10.37745/gjar.2013

Papadakis, I. E., Antonopoulou, C., Sotiropoulos, T., Chatzissavvidis, C., and Therios, I. (2023). “Effect of magnesium on mineral nutrition, chlorophyll, proline and carbohydrate concentrations of sweet orange (Citrus sinensis cv. Newhall) plants,” Appl. Sci. 13(14), article 7995. https://doi.org/10.3390/app13147995

Patel, P. K., Kadivala, V. A. H., and Patel, V. N. (2019). “Role of sulphur in oilseed crops: A review,” J. Plant Dev. Sci., 11, 109-114.

Pergola, M., Persiani, A., Palese, A. M., Di Meo, V., Pastore, V., D’Adamo, C., and Celano, G. (2018). “Composting: The way for a sustainable agriculture,” Appl. Soil Ecol. 123, 744-750. https://doi.org/10.1016/j.apsoil.2017.10.016

Richardson, A. D., Duigan, S. P., and Berlyn, G. P. (2002). “An evaluation of noninvasive methods to estimate foliar chlorophyll content,” New Phytol. 153(1), 185-194. https://doi.org/10.1046/j.0028-646X.2001.00289.x

Roghanian, S., Hosseini, H. M., Savaghebi, G., Halajian, L., Jamei, M., and Etesami, H. (2012). “Effects of composted municipal waste and its leachate on some soil chemical properties and corn plant responses,” Int. J. Agric.- Res. Rev. 2(6), 801-814.

Roussos, P. A. (2020). “Climate change impacts on fruit trees and mitigation strategies of adverse effects,” AgroLife Sci. J. 9(2), 269-276.

Samanta, S., Singh, A., and Roychoudhury, A. (2020). “Involvement of sulfur in the regulation of abiotic stress tolerance in plants,” in: Protective Chemical Agents in the Amelioration of Plant Abiotic Stress: Biochemical and Molecular Perspectives, pp. 437-466.

Santisree, P., Adimulam, S.S., Bommineni, P., Bhatnagar-Mathur, P., and Sharma, K.K. (2019). “Hydrogen sulfide in plant abiotic stress tolerance: Progress and perspectives,” in: Reactive Oxygen, Nitrogen and Sulfur Species in Plants: Production, Metabolism, Signaling and Defense Mechanisms, John Wiley & Sons, New York, NY, USA, pp. 743–775.

Sax, M. S., Bassuk, N., Van Es, H., and Rakow, D. (2017). “Long-term remediation of compacted urban soils by physical fracturing and incorporation of compost,” Urban For. Urban Green. 24, 149-156. https://doi.org/10.1016/j.ufug.2017.03.023

Schulz, H., Dunst, G., and Glaser, B. (2014). “No effect level of co-composted biochar on plant growth and soil properties in a greenhouse experiment,” Agronomy 4(1), 34-51. https://doi.org/10.3390/agronomy4010034

Scotti, R., Pane, C., Spaccini, R., Palese, A. M., Piccolo, A., Celano, G., and Zaccardelli, M. (2016). “On-farm compost: A useful tool to improve soil quality under intensive farming systems,” Appl. Soil Ecol. 107, 13-23. https://doi.org/10.1016/j.apsoil.2016.05.004.

Senbayram, M., Gransee, A., Wahle, V., and Thiel, H. (2015). “Role of magnesium fertilisers in agriculture: Plant–soil continuum,” Crop Pasture Sci. 66(12), 1219-1229. https://doi.org/10.1016/j.scienta.2007.04.012

Šircelj, H., Tausz, M., Grill, D., and Batič, F. (2007). “Detecting different levels of drought stress in apple trees (Malus domestica Borkh.) with selected biochemical and physiological parameters,” Sci. Hortic. 113(4), 362-369. https://doi.org/10.1016/j.scienta.2007.04.012

Snedecor, G. W., and Cochran, W. G. (1990). Statistical Methods, 6th Ed., Iowa State University Press: Ames, IA, USA.

Sultana, M., Jahiruddin, M., Islam, M. R., Rahman, M. M., Abedin, M. A., and Al Mahmud, A. (2021). “Nitrogen, phosphorus and sulphur mineralization in soil treated with amended municipal solid waste compost under aerobic and anaerobic conditions,” Int. J. Recycl. Org. Waste Agric. 10(3), article 245. https://doi.org/10.30486/IJROWA.2021.1908103.1124

Thompson, A. A., Williams, M. A., and Peck, G. M. (2019). “Compost and Geneva® series rootstocks increase young ‘Gala’ apple tree growth and change root-zone microbial communities,” Sci. Hortic. 256, article 108573. https://doi.org/10.1016/j.scienta.2019.108573

Tian, G., Qin, H., Liu, C., Xing, Y., Feng, Z., Xu, X., Liu, J., Lyu, M., Jiang, H., and Zhu, Z. (2023). “Magnesium improved fruit quality by regulating photosynthetic nitrogen use efficiency, carbon–nitrogen metabolism, and anthocyanin biosynthesis in ‘Red Fuji’apple,” Front. Plant Sci. 14, article 1136179. https://doi.org/10.3389/fpls.2023.1136179

Tian, X.-Y., He, D.-D., Bai, S., Zeng, W.-Z., Wang, Z., Wang, M., Wu, L.-Q., and Chen, Z.-C. (2021). “Physiological and molecular advances in magnesium nutrition of plants,” Plant Soil 468(1), 1-17. https://doi.org/10.1007/s11104-021-05139-w

Ud Din, M. M., Khan, M. I., Azam, M., Ali, M. H., Qadri, R., Naveed, M., and Nasir, A. (2023). “Effect of biochar and compost addition on mitigating salinity stress and improving fruit quality of tomato,” Agronomy 13(9), article 2197. https://doi.org/10.3390/agronomy13092197

Verbruggen, N., and Hermans, C. (2013). “Physiological and molecular responses to magnesium nutritional imbalance in plants,” Plant Soil, 368(1), 87-99. DOI 10.1007/s11104-013-1589-0

Wang, D., Lin, J. Y., Sayre, J. M., Schmidt, R., Fonte, S. J., Rodrigues, J. L., and Scow, K. M. (2022). “Compost amendment maintains soil structure and carbon storage by increasing available carbon and microbial biomass in agricultural soil–A six-year field study,” Geoderma 427, article 116117. https://doi.org/10.1016/j.geoderma.2022.116117

Wang, L., Sun, X., Li, S., Zhang, T., Zhang, W., and Zhai, P. (2014). “Application of organic amendments to a coastal saline soil in North China: Effects on soil physical and chemical properties and tree growth,” PloS one 9(2), article e89185. https://doi.org/10.1371/journal.pone.0089185

Wang, Z., Hassan, M. U., Nadeem, F., Wu, L., Zhang, F., and Li, X. (2020). “Magnesium fertilization improves crop yield in most production systems: A meta-analysis,” Front. Plant Sci. 10, article 495191. https://doi.org/10.3389/fpls.2019.01727

Wang, Z., Li, G., Sun, H., Ma, L., Guo, Y., Zhao, Z., Gao, H., and Mei, L. (2018). “Effects of drought stress on photosynthesis and photosynthetic electron transport chain in young apple tree leaves,” Biol. Open 7(11), article bio035279. https://doi.org/10.1242/bio.035279

Xu, J., Wu, L., Tong, B., Yin, J., Huang, Z., Li, W., and Li, X. (2021). “Magnesium supplementation alters leaf metabolic pathways for higher flavor quality of oolong tea,” Agriculture 11(2), article 120. https://doi.org/10.3390/agriculture11020120

Yang, W., Zhang, X., Wu, L., Rensing, C., and Xing, S. (2021). “Short-term application of magnesium fertilizer affected soil microbial biomass, activity, and community structure,” J. Soil Sci. Plant Nutr. 21(1), 675-689. https://doi.org/10.1007/s42729-020-00392-x

Ye, X., Chen, X.-F., Deng, C.-L., Yang, L.-T., Lai, N.-W., Guo, J.-X., and Chen, L.-S. (2019). “Magnesium-deficiency effects on pigments, photosynthesis and photosynthetic electron transport of leaves, and nutrients of leaf blades and veins in Citrus sinensis seedlings,” Plants 8(10), article 389. https://doi.org/10.3390/plants8100389

Zenda, T., Liu, S., Dong, A., and Duan, H. (2021). “Revisiting sulphur – The once neglected nutrient: It’s roles in plant growth, metabolism, stress tolerance and crop production,” Agriculture 11(7), article 626. https://doi.org/10.3390/agriculture11070626

Zhao, Z., Zhang, C., Li, F., Gao, S., and Zhang, J. (2020) “Effect of compost and inorganic fertilizer on organic carbon and activities of carbon cycle enzymes in aggregates of an intensively cultivated Vertisol,” PLoSONE 15, article e0229644. https://doi.org/10.1371/journal.pone.0229644

Article submitted: February 12, 2026; Peer review completed: May 9, 2026; Revised version received and accepted: June 17, 2026; Published: July 15, 2026.

DOI: 10.15376/biores.21.3.8275-8302