- Author: Rachael Freeman Long
- Author: Daniel H Putnam
- Author: Rollie Meyer
Published on: May 28, 2013
When is nitrogen fertilization of alfalfa beneficial? Almost never!
Nitrogen (N) fertilizer is generally not required for alfalfa production since alfalfa can obtain its own N from N-fixing nodules (Figure 1). Alfalfa fixes most (70-90%) of its N needs from the air through Rhizobium bacteria residing in alfalfa root nodules (Figure 1). Since 78% of our air consists of nitrogen gas, this supply of ‘free fertilizer' is inexhaustible. A recent unpublished UC Davis-CSU Fresno study showed 90% of N in alfalfa originated from the atmosphere -- but less when soil N levels were high, for example, in manured fields.
Although there have been some reports of yield and forage quality...
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