3 ideas
In Book I Columella ties an estate's results closely to the owner's frequent, direct supervision, warning that an absent master invites a careless steward, neglect of the work, and theft by the slaves. For land too distant for the owner to visit often, he advises leasing it to free tenant farmers rather than working it with slaves under a steward.
The vilicus should be chosen for proven practical experience and hardiness, not for charm or skill in the city trades, because a manager who has not done the work cannot judge it. He must be kept from idleness and luxury, must not lend or divine or wander off the estate, and must lead by working alongside the laborers. The owner controls him through fixed routines, regular inspection, and clear duties rather than trust alone.
Columella rejects the common complaint that the earth has grown old and exhausted, like an aging woman past childbearing. He argues that declining yields come from negligent husbandry, and that land kept up with manuring, proper plowing, and crop rotation with legumes keeps its productive capacity. Blaming nature for results that management caused hides the fixable cause.