Fig. 8
There was a significant quadratic relationship between MAT and maize
yield under NT (R2 = 0.408, P < 0.001, Fig.
8a) and RT (R2 = 0.576, P < 0.001, Fig. 8a),
with yield peaking at ~6.5 °C in both treatments before
declining. In contrast, a negative linear relationship was observed for
ST treatments (R2 = 0.335, P = 0.001, Fig. 8a). There
was also a significant positive linear relationship between maize yield
and MAP under NT (R2 = 0.089, P=0.035), and a
quadratic relationship under ST (R2=0.51,
P<0.001), although no significant relationship between maize
yield and MAP was observed for RT (Fig. 8b). However, under high MAP
condition (~700 mm) little difference was observed among
the three conservation tillage measures (Fig. 8b).
No significant relationships were observed between soybean yield and MAT
or MAP. However, there was a trend for a negative linear relationship
between yield and MAT under NT and RT, and a positive linear
relationship under ST (Fig. 8c). There was also a trend towards a
positive linear relationship were between soybean yield and MAP for all
tillage treatments (Fig. 8d).
The SOC concentration at 0-20 cm under NT (R2 = 0.758,
P < 0.001), RT (R2 = 0.932, P <
0.001) and ST (R2 = 0.655, P = 0.027) decreased with
increasing MAT (Fig. 9a). But the change in SOC as MAT increased above
7°C was minimal. A quadratic relationship was observed between SOC and
MAP for NT (R2 = 0.293, P = 0.003) and ST
(R2 = 0.886, P = 0.013) treatments, with SOC peaking
at ~ 600 and 500 mm in NT and ST treatments,
respectively, before declining (Fig. 9b). A significant positive linear
relationship was observed between SOC and MAP for RT treatments
(R2 = 0.762, P < 0.001), although only
limited datapoints (MAP range from ~500 to
~550 mm) were available, and further data is needed to
confirm this relationship.