Question:
We noticed yellowing of peanuts when oats were incorporated in conventionally tilled research plots. The yellowing looks typical of nitrogen or sulfur deficiency. I checked and the yellow peanuts have adequate nodulation and the nodules are active. Is there a relationship between nutrients and the decomposition of the oat biomass or could be related to allelopathy? The response is visible to the row compared to the strip tillage fallow treatment. The standing oat treatment shows a little chlorosis, but nothing in comparison to the conventionally tilled treatment.
Jordan:
I suspect the oat residue is tying up N available in soil. It takes a while for nodulation to be established and early in the season N available in soil contributes to peanut growth. If no N is available because of decaying cover crop biomass, the peanuts would be N deficient.