A cubic yard contains 3x3x3= 27 cubic feet. A 3 gallon pail will hold about 1/3 cubic foot. So, 100 pails X 1/3 cubic feet = about 33 cubic feet, or a bit more than a cubic yard. Most companies will not deliliver that small amount. Probably, you could carry about 1/2 yard in a pickup truck. So, two loads ought to do it. I think I paid around $30 bucks per pickup load some years ago. It's probably changed by now. I would suggest that you try a 1/2 dozen of the small pails first. For a tomato, there might be too little room for the roots in a pail that small. Maybe someone else may have more information for you. I talked to a fellow who said they grew their hydroponic tomatoes in sawdust with real good results. I think they used gunney bags for the containers. chuck

Just don't do like some first-time pickup owners and think that the size of the bed is the only concern with what the truck can haul.

If you're hauling gravel or dirt you can't even fill the bed halfway in most trucks. I've seen a guy going down the highway in a truck that had the bed full to the side rails with dirt and he was practically dragging the rear bumper.

An hour later when I was coming back I saw him again. He'd made it another quarter mile before the rear suspension failed catastrophically and ended the life of the truck.

So keep an eye on the weight you're adding and don't go over what the truck can handle. Rocks are heavy.