Figure 3. Expected effect of the stage of ¹⁵N distribution on the ¹⁵N uptake and residual ¹⁵N uptake after silking. With an early stage of ¹⁵N labeling (e.g., at two adult leaf stage) the residual ¹⁵N uptake after silking could be about only 5%, whereas with a later ¹⁵N labeling (e.g., at the six-leaf stage), it could be higher than 15%.