I use my kids’ plastic sleds in summer to wash garden greens. A sled is big enough to do a large amount at once. The greens I raise, kale and turnip, are thoroughly washed a couple times in the clean sled with my garden hose and then brought inside the house for a final rinsing and cooking. After they cool, I put them in storage bags and freeze them.
A sled also works well under the rabbit hutch to collect manure. I use one old sled to collect droppings, and then I pull it out from under the hutch when it is full and drag it down the hill to dump out near my garden. I shovel this pile onto my garden after the manure has had a chance to sit awhile.