Exercise 1 solution

Example answer (yours will differ):
Last year's layout matches year 1 of the table: legumes in A, brassicas in B, roots in C, others in D. Moving each group one bed along gives year 2:
Bed A: courgettes (others)
Bed B: beans (legumes)
Bed C: cabbages (brassicas)
Bed D: potatoes (roots)

The cabbages move from B to C. One reason: pests and diseases that favour brassicas, such as clubroot, build up in soil where they have grown, so a break lowers the risk. A second: the brassicas are hungry for nitrogen, and bed C held potatoes, while the beans (which add nitrogen) now sit in B for the next brassicas to follow the year after.