Improving soybean yield and oil productivity: an integrated nutrient management approach for sustainable soybean production

Introduction

As global food demand continues to rise, the importance of sustainable agricultural practices becomes increasingly urgent. Among the essential crops contributing to food security, soybean (Glycine max) stands out as a vital source of protein and edible oil for both human and animal consumption. With its multifaceted utility in food products, feed, and industrial applications, soybean plays a critical role in the global agricultural economy.

Yet, despite its importance, soybean productivity in many regions remains suboptimal due to declining soil fertility, imbalanced nutrient use, and the unsustainable over-reliance on chemical fertilizers. These challenges are compounded by the adverse effects of climate change and land degradation. In this context, Integrated Nutrient Management (INM) emerges as a strategic, science-based approach to not only improve soybean yield and oil quality but also to foster long-term agricultural sustainability.

What is Integrated Nutrient Management (INM)?

Integrated Nutrient Management is the practice of optimally combining organic, inorganic, and biological sources of plant nutrients to maintain or improve soil fertility and crop productivity. It emphasizes the balanced and site-specific application of:

• Chemical fertilizers (e.g., nitrogen, phosphorus, potassium),

• Organic manures (e.g., compost, farmyard manure),

• Biofertilizers (e.g., Rhizobium, phosphate-solubilizing bacteria, mycorrhizae),

• And in modern contexts, emerging tools like nanofertilizers and precision nutrient application technologies.

The goal of INM is to ensure that crops receive the right nutrient sources, in the right amounts, at the right time, and in the right manner—often referred to as the 4R Nutrient Stewardship principle (Right Source, Right Rate, Right Time, Right Place).

Why Focus on Soybean?

Soybean has a unique role in agriculture due to its nitrogen-fixing ability, thanks to its symbiotic relationship with Rhizobium bacteria, which reduces the need for nitrogen fertilizers. However, other nutrients like phosphorus, potassium, sulfur, and micronutrients are still crucial for optimal growth, flowering, pod development, and oil synthesis.

Additionally, soybean oil is one of the most consumed vegetable oils worldwide. Improving both yield and oil content is essential to meet increasing demands and ensure that soybean production remains profitable and competitive.

The Benefits of INM in Soybean Cultivation

1. Enhanced Yield and Oil Quality
   Multiple studies have demonstrated that integrated nutrient application results in higher and more consistent soybean yields compared to exclusive reliance on either organic or chemical inputs. Biofertilizers improve root health and nutrient uptake, while compost and manures enhance soil organic matter and microbial activity, both of which contribute to better grain and oil quality.

2. Improved Nutrient Use Efficiency (NUE)
   INM optimizes the timing and form of nutrient delivery, reducing nutrient losses due to leaching, volatilization, or runoff. This leads to improved nutrient use efficiency, meaning more of the applied nutrients are taken up by the plant rather than lost to the environment.

3. Soil Health and Fertility Restoration
   Continuous application of only chemical fertilizers has led to soil acidification, compaction, and biological degradation in many regions. Integrating organic and biological sources replenishes soil carbon, enhances microbial biodiversity, and improves soil structure, aeration, and water retention—key components of long-term soil fertility.

4. Reduced Environmental Impact
   Excessive use of synthetic fertilizers contributes to greenhouse gas emissions, eutrophication of water bodies, and soil toxicity. INM reduces these risks by lowering chemical dependency and promoting eco-friendly alternatives.

5. Cost-Effective and Farmer-Friendly
   Incorporating farm-produced compost or locally available biofertilizers can reduce input costs. Moreover, improving yield stability and soil health translates into better returns over time, especially for smallholder farmers.

Relevance in the Era of Climate Change

Agriculture is both a victim and contributor to climate change. Extreme weather, erratic rainfall, and rising temperatures affect crop productivity and soil quality. On the other hand, unsustainable practices, including over-fertilization, contribute significantly to greenhouse gas emissions (e.g., nitrous oxide from nitrogen fertilizers).

INM offers a climate-smart solution, improving the resilience of soybean cropping systems while minimizing their carbon footprint. For instance, by encouraging biological nitrogen fixation and reducing synthetic nitrogen inputs, INM helps lower nitrous oxide emissions. Moreover, practices that build soil organic carbon through composting and cover cropping also contribute to carbon sequestration.

Challenges and Considerations

While the benefits are well-documented, successful adoption of INM in soybean cultivation faces several challenges:

• Knowledge gaps among farmers regarding balanced nutrient management.

• Limited access to quality biofertilizers and organic inputs.

• Need for localized research to develop crop- and soil-specific INM recommendations.

• Policy and subsidy structures that still heavily favor chemical fertilizer use.

Addressing these requires an integrated effort involving extension services, research institutions, policy reforms, and private sector partnerships to make INM technologies accessible, affordable, and scalable.

Moving Forward: Policy and Practice

To mainstream INM in soybean farming, especially in regions with fragile agro-ecosystems, the following steps are recommended:

• Capacity Building and Farmer Training: Extension programs should focus on training farmers in INM principles and application techniques.

• Incentives for Organic and Bio-based Inputs: Policies that promote composting, vermiculture, and biofertilizer production can support the availability of sustainable inputs.

• Investment in Research and Innovation: Continuous R&D is needed to refine INM packages tailored to different soybean-growing zones.

• Monitoring and Evaluation Tools: Implementing soil health cards and digital advisory platforms can guide farmers on nutrient needs more precisely.

Conclusion

Improving soybean yield and oil productivity through Integrated Nutrient Management is more than an agronomic technique—it is a pillar of sustainable agriculture. By blending tradition with technology, INM empowers farmers to increase productivity while preserving the environment. As the global community pushes toward food security, climate resilience, and ecological balance, INM stands out as a proven and scalable solution—especially in crops as strategically important as soybean.

Adopting and promoting this approach will not only help meet present demands but also secure a healthier planet for future generations.