Soybeans at a Crossroads: Addressing Declining Soil Fertility to Secure Future Yields
Soybean production is a cornerstone of the regional agricultural economy, yet notable yield gaps – currently estimated at 30-35% – persist between actual and potential harvests. While genetics, water management, and agronomic practices all play a role, nutrient deficiencies are a critical limiting factor.
Recent analysis reveals a concerning trend: soybean crops are consistently removing more nutrients from the soil then are being replaced. Specifically, phosphorus (P) extraction exceeds fertilization by an average of 11 kg/ha, and sulfur (S) by 7 kg/ha. This sustained negative nutrient balance is depleting soil fertility, threatening long-term productivity and competitiveness.
Current soil surveys paint a stark picture:
* 42% of agricultural land suffers from low phosphorus (P) levels,hindering soybean performance and impacting the efficiency of other nutrient uptake,including nitrogen fixation.
* Micronutrient deficiencies – zinc (Zn) and boron (B) – are prevalent in 56% of fields, impacting reproductive processes, grain growth, and overall quality.
* Average soil organic matter (MO) has declined by 1.2% from its original levels, a key indicator of declining overall soil health – chemical, physical, and biological.
These findings underscore the need to move beyond a fragmented approach to soil nutrition. Strategic fertilization, guided by accurate diagnosis and ongoing monitoring, is essential, but insufficient on its own. A truly sustainable solution requires an integrated management system that prioritizes soil health through practices like:
* Crop rotation with grasses
* Incorporation of cover crops
* Rational fertilizer application
* Continuous monitoring of soil quality indicators
The data is clear: soybean yields are at risk due to declining soil fertility. Addressing negative nutrient balances, widespread deficiencies, and organic matter loss is not just a best practice, but a necessity. A paradigm shift is required – one that embraces a systemic approach to close yield gaps, replenish nutrients, and build long-term soil health. This demands increased investment in soil diagnosis, strategic fertilization, and the integration of innovative technologies and processes to safeguard the future of soybean production.
Authors: Hernán Sainz Rozas, Specialist in Soil Fertility of INTA Balcarce and Nahuel Reussi Calvo, researcher at CONICET and the National University of Mar del Plata.
