Fertilising soybeans has proven to be a beneficial practice for many soybean growers seeking to improve yield and plant health. This guide explains the importance of foliar fertilisation, the primary nutrients required, and best practices for fertilising soybeans under various conditions. Proper nutrient management can greatly enhance the resilience, yield, and profitability of soybeans.

Why Foliar Fertilisation Matters for Soybeans

Foliar fertilisation is the practice of applying nutrients directly onto the plant leaves. This method allows plants to absorb essential nutrients right where they are applied, particularly beneficial during growth phases that require high nutrient availability. Foliar fertilisation is often used alongside soil fertilisation to enhance nutrient uptake, especially in adverse conditions such as drought or nutrient-poor soils.

Foliar applications of potassium nitrate, for example, support vital plant functions, especially during the pod formation stage. Potassium helps prevent nutrient losses, improves photosynthesis, and bolsters root health, enabling plants to better withstand environmental stressors. Studies have demonstrated that well-nourished soybean plants yield more and resist diseases more effectively than nutrient-deficient plants.

Essential Nutrients for Optimal Soybean Growth

  1. Nitrogen (N): Although soybeans can fix nitrogen from the atmosphere, they require substantial amounts of nitrogen, especially during seed formation. Nitrogen deficiency often presents as yellowing leaves and can reduce overall plant health.
  2. Phosphorus (P): Phosphorus is essential for root development and energy transfer. It supports seed production and overall plant vigour, with deficiencies often presenting as stunted growth and dark-green leaves with purple undertones.
  3. Potassium (K): Potassium aids in water regulation, photosynthesis, and disease resistance. It is particularly critical during flowering and seed development. Potassium deficiency can lead to leaf chlorosis (yellowing) and, in severe cases, can impact the entire plant.
  4. Other Micronutrients: Elements like iron, calcium, and sulphur play supportive roles in soybean growth. Iron, for instance, is necessary for nodule formation and nitrogen fixation, while calcium aids in new leaf development.

Soybean Nutrient Needs Throughout Growth Stages

Soybeans demand higher nutrient levels during seed filling, the critical period when nitrogen, phosphorus, and potassium levels should peak. Late-season nutrient mobilisation from older leaves to developing seeds helps ensure a high-protein yield. However, soil and foliar nutrient application may be needed to meet the plant’s demands, especially if previous crops depleted soil nutrients.

Field Practices for Improved Yield

  • Soil Sampling: Regular soil sampling every two years helps monitor nutrient levels, allowing for adjustments based on actual field needs. For high-yield crops, sampling annually is beneficial, especially for no-till systems, which can lead to nutrient stratification.
  • Foliar Fertilisation in Nutrient-Limited Conditions: For sandy soils or high-yield fields, foliar fertilisation can offer a supplemental nutrient boost. However, studies suggest that foliar application is most beneficial in approximately 15–20% of cases where nutrient limitations exist.
  • Proper Potash Management: While potash application doesn’t always show immediate results, it can improve potassium availability over time. In fields with high-yielding corn preceding soybeans, additional potassium may be required to counteract soil depletion from previous crops.

Conclusion

For Australian farmers aiming for high yields, fertilisation based on soil tests is critical. Regular soil testing, combined with foliar fertilisation during peak growth stages, helps ensure that soybean plants receive the nutrients they need. Nutrient deficiencies can hinder growth, limit yield potential, and increase susceptibility to diseases. With soybeans being a high-value crop, ensuring they receive adequate nutrition through strategic fertilisation and soil management can lead to healthier plants and increased profits.

Maximise Soybean Yields with Nano Urea

Boost your soybean growth and yields with Nano Urea liquid urea fertiliser, specially designed for precise nutrient delivery. For optimal results, apply Nano Urea at 1.5 L/Ha 30–35 days after sowing or 20–25 days after transplanting. For multi-harvest crops, continue with a foliar spray after each harvest to maintain nutrient availability and support plant health. Nano Urea ensures your soybeans receive the nutrition they need during critical growth stages, leading to healthier plants and higher profitability.