Fig. 2.
Annual grain energy output versus fossil-fuel energy input for middle-season rice (MR), double-season rice (DR), and ratoon rice (RR) farmer fields. Separate linear regressions were fitted for each cropping system; parameters and coefficients of determination (r2) are shown. Asterisks indicate that the slope of the fitted linear regression was statistically different from zero (P < 0.01). Insets show boxplots for net energy yield (NEY) and net energy ratio (NER), with solid and dotted lines inside the box indicating median and mean values, respectively, box boundaries denoting the upper and lower quartiles, whiskers representing the 10th and 90th percentiles, and the circles representing the 95th and 5th percentiles. Letters indicate statistically significant differences (LSD test, P < 0.01). Overall regression for the pooled data including the three cropping systems: y = 3.9 x + 28 (r2= 0.70; P<0.01)