Molecular Soil Biology 2024, Vol.15, No.5, 216-226 http://bioscipublisher.com/index.php/msb 217 negatively impact early plant establishment and overall plant density, highlighting the need for appropriate soil management strategies (Adamič and Leskovšek, 2021). This study explores the combined effects of irrigation and fertilization on soybean growth and yield across different soil types, aiming to provide insights on how to optimize these practices to enhance soybean productivity while minimizing environmental impacts. By examining the interactions between soil types, irrigation, and fertilization, this study seeks to contribute to the development of sustainable soybean cultivation practices that can adapt to diverse agricultural ecological conditions. 2 Irrigation and Soybean Growth 2.1 Types of irrigation methods in soybean cultivation Soybean cultivation employs various irrigation methods to optimize water use and enhance crop yield. Common methods include sprinkler irrigation, drip irrigation, and surface irrigation. Sprinkler irrigation is widely used due to its ability to uniformly distribute water across the field, which is particularly beneficial in temperate climates with variable precipitation (Gajić et al., 2018). Drip irrigation, on the other hand, is highly efficient in water-scarce regions as it delivers water directly to the root zone, minimizing evaporation losses and improving water use efficiency (Chomsang et al., 2021). Surface irrigation, though less efficient, is still practiced in some areas due to its simplicity and lower initial costs. 2.2 Water requirements for soybean growth Soybean plants have specific water requirements that vary across different growth stages. Adequate water supply is crucial during the reproductive stages (R1-R8) to ensure optimal growth and yield. Studies have shown that supplemental irrigation during these stages can significantly enhance total dry matter and leaf area index, leading to higher grain yields (Montoya et al., 2017). The crop coefficients (Kc) used to estimate actual evapotranspiration (ETa) can be generalized for different regions, aiding in the efficient planning of irrigation schedules. 2.3 Impact of water stress and over-irrigation on soybean yield Water stress at critical growth stages can severely impact soybean yield. For instance, drought stress during the early flowering to pod development stages (R1-R4) can reduce seed yields by up to 46% (Eck et al., 1987). Similarly, over-irrigation can lead to reduced water use efficiency and increased susceptibility to diseases. A study found that maintaining soil moisture at 75% of the maximum soil water holding capacity resulted in better yield outcomes compared to both higher and lower moisture levels (Gebre and Earl, 2021). Over-irrigation not only wastes water but also negatively affects the harvest index and overall productivity (Gajić et al., 2018). 2.4 Adaptation strategies for optimizing irrigation To optimize irrigation in soybean cultivation, several adaptation strategies can be employed. One effective approach is the use of deficit irrigation, where water is applied at critical growth stages to avoid stress during the most sensitive periods (Sweeney et al., 2003). Additionally, integrating potassium fertilization with irrigation can improve plant water status and physiological responses, thereby enhancing yield under water-deficit conditions (El-Mageed et al., 2017). The use of plant growth-promoting microbes (PGPMs) and nanoparticles (Si-ZnNPs) has also shown promise in mitigating the adverse effects of water stress and salinity, leading to improved growth and productivity (Osman et al., 2021) (Figure 1). These strategies collectively help in achieving sustainable water management and maximizing soybean yield. 3 Fertilization and Soybean Growth 3.1 Nutrient requirements for soybean growth Soybean growth and development require a balanced supply of both macronutrients and micronutrients. Key macronutrients include nitrogen (N), phosphorus (P), and potassium (K), which are essential for various physiological processes. Nitrogen is crucial for protein synthesis and overall plant growth, phosphorus is vital for energy transfer and root development, and potassium plays a significant role in water regulation and enzyme activation (Basal and Szabó, 2020; Li et al., 2022). Micronutrients such as zinc (Zn), boron (B), manganese (Mn),
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