All legume plants can fix nitrogen in the right conditions. Nodules are the swollen, rounded lumps that are formed on the roots of legumes. However unless they are forming nodules they are unlikely to be fixing much nitrogen.
What to record
Score of 1-3 for amount of nodules observed where:
1. None – little or no nodules, or small numbers of nodules that are small
2. Some – moderate number of nodules found, of varying size
3. Many – nodules are present throughout the roots, some are pink in appearance
Bucket & water (for washing the soil from roots)
How to do the test
1. Locate your chosen sample site – you can use the GPS mapping feature on the app to do this if you’ve recorded the sample locations previously.
2. Dig out a small section of soil, no wider than your spade or do with other spade test/VESS test.
3. Gently break (or wash) away soil from roots of legumes