Molecular Soil Biology 2025, Vol.16, No.4, 175-187 http://bioscipublisher.com/index.php/msb 1 82 8 Nutrient Management and Fertilization 8.1 Essential nutrients for optimal sweet potato yield Sweet potato (Ipomoea batatas L.) requires a balanced supply of essential nutrients to achieve optimal yield. Key macronutrients include nitrogen (N), phosphorus (P), and potassium (K), which play critical roles in plant growth and development. Nitrogen is vital for vegetative growth, phosphorus is essential for energy transfer and root development, and potassium is crucial for water regulation and enzyme activation (Koch et al., 2019; Fernandes and Ribeiro, 2020). Additionally, secondary nutrients such as calcium (Ca), magnesium (Mg), and sulfur (S) are important for various physiological functions and overall plant health (Koch et al., 2019). Micronutrients, though required in smaller quantities, are also essential for maximizing yield and quality (Fernandes and Ribeiro, 2020). 8.2 Organic vs. synthetic fertilizers The choice between organic and synthetic fertilizers can significantly impact sweet potato yield and soil health. Organic fertilizers, such as poultry and bovine manure, improve soil chemical attributes and enhance the production and quality of sweet potatoes (Nunes et al., 2020). They also contribute to long-term soil fertility by increasing organic matter content (Karkee and Bishwokarma, 2023). On the other hand, synthetic fertilizers provide a more immediate nutrient supply, which can lead to higher yields in the short term (Yadav et al., 2017). However, the integration of both organic and synthetic fertilizers has been shown to be more effective. For instance, combining 75% of the recommended dose of synthetic fertilizers with 25% of nitrogen from farmyard manure (FYM) resulted in higher productivity and better soil health (Yadav et al., 2017; Shabitha and Rajeswari, 2021). This integrated approach leverages the benefits of both fertilizer types, ensuring sustainable production. 8.3 Timing and application techniques for fertilizers The timing and method of fertilizer application are crucial for maximizing sweet potato yields. Split application techniques, where fertilizers are applied at different growth stages, have been shown to significantly increase yields. For example, applying a base fertilizer before planting and supplementing with additional liquid fertilization during the growing season resulted in up to a 36% increase in yields for certain sweet potato varieties (Balázs et al., 2023). Similarly, the use of biofertilizers in combination with NPK fertilizers during specific growth stages can enhance nutrient uptake and boost yield (Mukhongo et al., 2017). The Nutrient Expert (NE) system, which optimizes fertilizer input and implements split fertilization, has also been effective in improving potato productivity and tuber quality (Sha et al., 2021). This system increased total and marketable tuber yields by 12%~15% and 16%~26%, respectively, compared to traditional farmer practices (Sha et al., 2021). 9 Harvesting Handling 9.1 Indicators of maturity and optimal harvest time Identifying the optimal harvest time for sweet potatoes is crucial for maximizing both yield and quality. Sweet potatoes are typically harvested around 120 days after planting, but this can vary depending on the variety and growing conditions. Delaying the harvest to 150 or 180 days can enhance the content of bioactive compound and post-harvest quality, especially in varieties with orange pulp, which exhibit increased levels of β-carotene and antioxidant activity (Simões et al., 2020). It's also important to harvest in a timely manner to prevent decay losses, such as tip rot, which is exacerbated by late harvesting (Sugri et al., 2020). 9.2 Techniques for reducing harvest losses To minimize harvest losses, several techniques can be employed. Careful handling during harvest is essential to avoid physical damage to the tubers, which can lead to microbial decay. Techniques such as root tip coppicing, hot water treatment, and honey waxing have been shown to significantly reduce post-harvest losses by preventing sprouting and microbial infection (Sugri et al., 2020). Moreover, harvesting intervals can impact yield; for example, a 20-day interval between harvests can result in higher leaf and stem dry matter yields, which is beneficial for overall plant health and productivity (An et al., 2003). 10 Conclusion Remarks The review of high-yielding sweet potato cultivation techniques reveals several critical strategies that significantly
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