- Author: Rachael Freeman Long
- Author: Daniel H Putnam
Published on: February 10, 2017
Yellow plants equals nitrogen deficits—right? Maybe not!
When we have a very wet winter or spring, alfalfa fields may look yellow with diseased-looking leaves and delayed growth.
As farmers know, yellowing of leaves is a strong indication that nitrogen (N) may be limiting in the crop. Certainly that's true with corn, tomato, or wheat. It may also be the case in alfalfa too – but since alfalfa is a legume, it gets most of its N from biological nitrogen fixation (N2 fixation from bacteria which colonizes the roots, forming nodules), not from the soil. This ability enables alfalfa to grow well even on sandy N-depleted soils. N fertilizers are generally not recommended...
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