design("Mario's plant pathologist problem") %>%
set_units(rep = 3,
col = 12,
row = 12,
# so 3 x 12 x 12 pots in total?
pot = crossed_by(rep, col, row),
# 4 varieties fit per pot so 4 units per pot?
unit = nested_in(pot, 4)) %>%
set_trts(barley = 576) %>%
allot_table(barley ~ unit)
The design below takes about 13 minutes to run: