Okay, more information helps.
The poster above mentioned planting other things in there, which is a great idea. Comfrey is a useful plant but plant it sparingly as once you put it in a spot you will always have it in the spot. That said, on a place that large and watering as you do, you are never going to be done weeding, especially with bare ground. The joy of having bare ground is you can plant good stuff in there, put in some cover crops, tall ones in your case to shade out the weeds, mulch in late winter to cover last years seed deliveries and after anytime you flood. Another method would be to set up some zones or paddocks and run chickens through, they will eat everything green.
Also, hoeing a large area with young sprouts is fast, hoeing gets progressively slower the bigger things get. Buy a Hula Hoe like this one
$20 Hula Hoe and hoe stuff when it is small, these are very easy to use and fast.
Also, no matter which hoe you use, keep them sharpened. Doesn't need to be razor sharp but more like a dull knife blade, they come from the factory almost round and the ease of using one rapidly increases the sharper you get it.