Enhancing Biological Nitrogen Fixation Through Diverse Pasture Swards

Area of Science:

• Agricultural Science
• Agronomy
• Soil Science

Background:

• Regenerative agriculture utilizes diverse pasture species for sustainable production.
• Incorporating legumes into pastures can increase biological N fixation (BNF), reducing synthetic N fertilizer reliance.

Purpose of the Study:

• Quantify BNF in diverse vs. standard pastures.
• Assess legume performance for improved N supply and pasture quality.
• Evaluate year-round seasonal BNF through various indicators.

Main Methods:

• Field study comparing diverse (9 species) and standard (ryegrass/clover) pastures.
• Assessed soil N status, nodulation, plant composition, and 15N natural abundance.
• Evaluated dry matter production and nitrogen yield.

Main Results:

• Diverse pastures yielded 5.4% more dry matter and 9.3% higher N yield than standard pastures.
• Soil mineral N levels were similar between pasture types.
• BNF increased 3-fold in diverse pastures from winter to summer, compared to 1.5-fold in standard pastures.
• Optimal BNF occurred at moderate clover proportions (up to 30%) in both systems.

Conclusions:

• Diverse pastures can enhance seasonal BNF and overall productivity.
• Strategic management is key to maximizing BNF benefits in diverse swards.
• These findings support the use of diverse pastures for sustainable N management in agriculture.