No Spiritecho, there is not sand that would blow up and conceal a body. Weeds or tall grass, yes. The ground has a tendency to be hard packed unless it is plowed. Even plowed, it would not blow up and conceal anyone. If Brandon was "in a field" as he stated, to me that would indicate a plowed field or a field of permanent grass such as haygrazer or buffalo grass. A field in Texas usually gets plowed and planted, but not always. A field to me as a native Texan of this area indicates a rather flat area with something planted and growing or freshly plowed. I would think if he were in a field, he could be found rather easily because of a lack of trees and also if it were plowed, someone would have come across his body by now.
On the other hand, a pasture would indicate an area of mesquite trees, cedar trees, some native grass and some sort of scrub brush. Pastures are usually not plowed , but cattle or other livestock could roam the area and graze the native grasses. Pasture could be pretty thick with brush and could hide a body well. It might be difficult to find Brandon if he was in a pasture where people and equipment do not go very often. He could be well hidden there.
In Texas, fields are fenced off and have a tendency to be rather small areas. Whereas a pasture is fenced off also, but it can consist of hundreds of acres.
Hope this helps you visualize the land. I have some pictures of the area. I will try to get them uploaded.