Ask Mr. Smarty Plants

Sclerocarpus uniserialis (Mexican bonebract) would not ordinarily be considered a candidate for transplanting, because it is an annual and you would expect to propagate it by the natural dropping of seeds. However, in your situation, where you have only the one, and the cattle are after it, you will be better off moving it. It blooms from August to January, so you would consider it a winter annual. The best plan would be to transplant it now, giving it time to recover, re-bloom, and seed in its new location. 

First, prepare a hole, estimating how big a soil ball you can take out of the ground with your plant in it. If the plant is presently growing in full sun, transplant it to a similar light exposure area, and so forth. Since this plant is growing voluntarily in your natural soil, you probably shouldn't worry too much about soil amendment, but it never hurts to work some compost into a hole for a new plant.  Not only does this improve drainage, always important, but will add some nutrients for the newly arrived plant. The roots of an annual are not going to be as deep and as wide as those of a perennial, so just stick a sharp shovel into the dirt, perhaps around the outer edge (or "dripline") of the plant, get a shovel sized distance down, and go all the way around. Then, lift and loosen the plant, keeping as much of the soil on the roots as you can manage and move into its new hole. Place it so that the soil at the base of the plant is on the same level as the soil at the new location. Put the extra dirt back in around the roots. Stick a hose into the hole, and let it dribble gently until water comes to the surface. Do this about every other day, unless you are getting pretty regular rain. Don't fertilize, other than whatever nutrients are in the compost. A transplanted plant is a plant in shock, and you should never fertilize a stressed plant. Hopefully, it will not even wilt, or drop blooms, but if it does, just nip off the affected areas and keep treating it with water dribbles. You should be able to either let it normally reseed or wait until the seeds are dry on the plant and harvest them yourself. And keep an eye out on the area in your pasture where you found it. Next Spring, when new plants are sprouting, you may find some children of your "one" plant popping up, from seeds it dropped there this Fall. 

Sclerocarpus uniserialis

Sclerocarpus uniserialis

Sclerocarpus uniserialis

Sclerocarpus uniserialis