The master of the LUA has taken up the torch of the ProSeed mod. This very particular script allows the player to stake out and leave the wheel marks when sowing. Once the culture has emerged, the traces will guide you for your spraying. Wopster took this mod from A to Z and made it compatible with his GPS mod (Guidance Steering) for fully automatic use.
But rather than a long and tedious description of this unique mod, I refer you to the video above which, in 10 minutes, explains its use in these 3 modes of operation. Wopster has also posted a mini guide (in English) to this address.