This was a major undertaking. Due to so many years with so many horses compacting the ground, the earth was extremely dense and solid. 
Digging out existing ditches and adding many more was our first task. The ground literally laughed at picks and shovels. Next it howled at using a small tractor. So, it was time for the big guns!
The horse ranch originally used flood irrigation from the ditches and natural runoff from neighbor's fields. This left a mucky mess of standing water, in the manure. The neighbors said the mosquitos were horrendous, and loved our efforts to turn the situation around.
Hemp plants due best in raised beds, with controlled drip irrigation lines. They won't tolerate their roots in standing water, which blocks oxygen and nutrients from being absorbed. This made ditches to control the water essential. We added about a quarter mile of new ditches, as well as cleaning out and widening all the old. Each year the cattails think we are doing all this for them. After this, the remaining weeds are burned. You have to notify the county on the day you plan on burning, so strong winds don't run away with the fire. They will tell you if you can burn or not.
Next, was prepping the fields so we could create raised beds. This required even larger, heavier equipment.
Here is photo of the tractor required to start plowing.
This tractor is pulling a six bottom plow. Anything less would take days to complete turning up 6 acres of packed clay soil. Even with the weight and power involved, it could only dig 8" deep. 
Here is the tractor methodically working through the middle field. 
This is the size of the clods that were dug up. You couldn't even hardly turn one over, let alone pick one up.
Here is what the fields looked like after plowing. 
Next, a disc implement was used to start breaking up the giant clods. 
It took many repetitive passes to break up the clods. The disc has two huge sets of opposing wheels, that reduce the clods into manageable clumps, at last giving us some hope. Unfortunately, these clumps were still too big to create raised beds.
The next step was tilling. This is an implement which grounds up the clumps to a size that allows raised beds to be formed. Luckily, this could be accomplished by our smaller tractor. 
We ran the tractor over the fields for several days. We had to run water over any area we were working on, to break up the dirt, and keep precious topsoil from blowing away. 
Eventually, the fields looked like this, and we would be able to create raised beds.
Finally, here I am surveying the hard work, feeling a sense of accomplishment.
Next post will be creating the raised beds, in preparation for setting up irrigation.