Total income is greater than r (<1) times the current income even if the area allocation is changed. However, it was not possible to attain an ideal outcome in which all the self-sufficiency rates are equal to or exceed 100 per cent (r = 1) at the same time. Under the condition 0 < r < 0.9, the result is shown in Figure 4.2.2. Recently, willow has received a lot of attention as an energy source, and it may be planted in the field as an agricultural crop (Eriksson, 2008; Heller et al., The lower panel shows the optimal allocation areas and the number of cows when r is changed.