Alfalfa: A Perennial Nitrogen-Fixing Forage Legume

Alfalfa is a perennial nitrogen-fixing forage legume capable of producing over 4,000 kg/ha of crude protein within three years and supplying approximately 300 kg/ha of nitrogen to subsequent crops (30-40% in the first year, 20-25% in the second, and 10-15% in the third).

Alfalfa has great synergy with maize cultivation, both from an agronomic standpoint (enhancing soil chemical and physical fertility) and in terms of nutrition for dairy cattle. It produces highly nutritious forage. Increasing farm self-sufficiency for protein feed reduces ration costs and increases farm independence from market fluctuations.

Symbiotic Nitrogen Fixation

Alfalfa’s root system naturally establishes a symbiotic relationship with rhizobia present in the soil. The specific rhizobium (Sinorhizobium meliloti) penetrates the roots, using the energy provided by the plant to fix atmospheric nitrogen and supply it in more than adequate amounts to sustain the plant's growth cycle.

A Deep Root System

By the end of the first year, alfalfa’s root system, comprising a taproot and a network of fine roots, allows the plant to reach soil depths of over 1.5 meters, providing significant drought resistance.

The development of a robust root system, continuous vegetative growth (about 240 days a year), soil coverage, and reduced need for soil tillage contribute to alfalfa’s role in environmental protection by mitigating soil erosion and nutrient runoff.

Improved Crop Yields

Crop rotation with alfalfa improves maize yields in successive plantings. Fields where maize followed alfalfa showed yields 10-14% higher than those in continuous maize monoculture, with a 35% lower direct and indirect consumption of non-renewable energy.

Rotation also helps reduce the pressure of harmful insects.

Increased Carbon Sequestration

Studies in various geographic areas have shown that crop systems including alfalfa rotations maintain a more stable stock of organic carbon in the soil compared to maize monoculture. Sequestering carbon in the soil through the accumulation of organic matter contributes significantly to mitigating climate change by reducing atmospheric CO2 levels.

Biodiversity and Landscape Conservation

The long lifespan of alfalfa’s growth cycle, along with the limited use of pesticides and fertilizers, makes it an excellent environment for preserving biodiversity.

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References

Tabacco E., Borreani G., 2014. "More Efficient Forage Systems with Alfalfa Cultivation." *L’Informatore Agrario*, 70. (1), 36-39.

Tabacco E., Giaccone D., Revello Chion A., Comino L., Borreani G., 2015. "Alfalfa: The Ideal Choice for Greening." *L’Informatore Agrario*, 71 (1), 2-5.