where NLmin is the minimum NL during the growing season (cf. Eq.
(2), gm−2), and the relationship of Eq. (5) is illustrated in Fig. 3b. Of
the two parameters in Eq. (5), Nb is the crop-specific minimum leaf
nitrogen content for photosynthesis (Yin et al., 2003) (gm−2) and
kn is the nitrogen extinction coefficient in the canopy. Nb and kn can