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Nitrogen Fixation in Your Pulse Crop JUN 19 2013 | Producers | Blog Post

One of the main benefits of including pulses in a crop rotation is their nitrogen fixation ability. But even if your pulse plants look healthy in the field, they may not be actively fixing nitrogen. Many factors can affect nodule formation and nitrogen fixation:

  • cool, dry weather
  • low pH soils
  • high nitrogen levels in the soil
  • low phosphorus levels in the soil
  • incompatibility with the inoculant and seed treatment
  • herbicide application

To find out if your pulses are fixing nitrogen, you’ll need to dig for the answer. Literally.

How to Assess Pulse Crop Nodulation

  • Conduct nodulation assessments during early flowering, as nitrogen fixation rates are generally highest at this point.
  • Dig – rather than pull – the plants from the ground to avoid losing root matter and nodules.
  • Gently but thoroughly wash the root system.
  • Randomly sample each plot, avoiding edges, and assess between two to 10 plants per plot depending on plot size and plant density.
  • Evaluate plant growth and vigour, nodule colour and number, and nodule position using this guide from 20/20 Seed Labs.

For more information, check out these “How To” videos by Kevin Zaychuk of 20/20 Seed Labs: