From the NYT:

ON a sunny Sunday just before the vernal equinox, Rich Ciotola set out to clear a pasture strewn with fallen wood. The just-thawed field was spongy, with grass sprouting under tangled branches. Late March and early April are farm-prep time here in the Berkshires, time to gear up for the growing season. But while many farms were oiling and gassing up tractors, Mr. Ciotola was setting out to prepare a pasture using a tool so old it seems almost revolutionary: a team of oxen.

Mr. Ciotola, 32, is one of a number of small farmers who are turning — or rather returning — to animal labor to help with farming. Before the humble ox was relegated to the role of historical re-enactor, driven by men in period garb for child-friendly festivals like pioneer days, it was a central beast of burden. After the Civil War, many farms switched from oxen to horses. Although Amish and Mennonite communities continue to use horses, by World War II most draft animals had been supplanted by machines that allowed for ever-faster production on bigger fields.

For more, see: On Small Farms, Hoof Power Returns