I find that hard to believe. A team of ox simply can’t do the same amount of work per time unit, that a tractor can. Plus, oxen down time (sleep, eat, rest, sick) is, of necessity, considerably longer than a tractor downtime (refuel).
Oxen-farming, while nostalgically attractive, will raise costs and create shortages.
The cost per acre is less, no fuel or chemicals. The down side is animal care and time.