I strongly suggest you stay away from what is referred to as genetically altered or modified seed. There are a lot of unanswered questions as to what these seeds do the the soil in the long term.

If you plat an annual, you should do a crop rotation. Planting the same annual year after year on the same soil invites problems with disease.

As roper asked what are you planning to sow? What you plant determines what you do with the soil.