Does this imply that plant nitrogen levels are highest as they reach the end of their life cycle?
A. We are looking for a 90-100% bloom. This is important for hairy vetch because we want to maximize our nitrogen percentage. If we’re talking about hay, farmers time their cuttings of alfalfa or clover to maximize protein, which is referring to nitrogen. In the case of green manures, we are talking about the same thing, but we refer to this as nitrogen tissue level. At this level of bloom, the amount of biomass, as well as the percentage of nitrogen in the tissue, is greatest. Q. How does the nitrogen from the biomass become available to the plants? A. Nitrogen from the mat gets into the soil through weathering and leaching. That is why we measure the above-ground biomass, which can be anywhere from 4,000 to 9,000 pounds per acre of dry matter. We multiply that by the tissue analysis which, if it’s earlier in the season, can give us anywhere from 100 to over 200 pounds of nitrogen per acre. This is available slowly as it decomposes and is leached down, but not all of it is available.
