Ineffective nodules are pale green or white inside. Generally, nodulation is visible one month after seeding, and the number of nodules increases until flowering. Plants stressed by weather or disease may not nodulate. High levels of soil nitrogen may inhibit nodule formation and activity. Soils should be sampled to zero to six and six-24 inch depths.
Beans are very sensitive to seed-placed fertilizer.
Seed burn will result in reduced stands or uneven emergence. All nitrogen, potassium and sulphur must be placed away from the seed. When applied as a starter, fertilizer should be placed in a band two inches to the side and two inches below the seed. Otherwise, broadcast applications or preplant banding is suggested. Inoculated field beans have responded to fertilizer nitrogen under certain conditions in Manitoba trials.