ON TKOF ROLL MOWER DRIVES ONTO RWY. TKOF ABORTED. BACK FOR A SECOND TRY. SAME THING HAPPENS AGAIN.

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A TRACTOR AND MOWER WAS CUTTING GRASS ON THE ARPT NEAR THE RWY AT THE TIME OF MY TKOF. I TAXIED TO RWY 17 AND COMPLETED MY ENG RUNS AND BEFORE TKOF CHKS AT OWI ARPT WHICH HAS A UNICOM 122.8 (CTAF). I HELD FOR A VFR DEP UNTIL AN ACFT IN THE PATTERN HAD COMPLETED A TOUCH AND GO. I LINED UP ON THE RWY AND CLRED THE RWY FOR TKOF. THE TRACTOR WITH MOWER WAS 75 FT TO THE R SIDE OF THE RWY 2000 FT DOWN; AS I RELEASED BRAKES THE MOWER DRIVER DROVE OUT ONTO THE RWY. I REDUCED PWR AND STOPPED AND AGAIN ANNOUNCED ON 122.8 (CTAF) MY INTENTIONS TO DEPART RWY 17. THE MOWER DRIVER CLRED THE RWY. I WAITED TO INSURE A SECOND TKOF ROLL WHEN THE MOWER DRIVER TURNED AND DROVE ONTO THE RWY AGAIN. I ABORTED TKOF AFTER 500 FT OF GND ROLL AND CLRED OFF THE RWY TO TAXI BACK TO THE DEP END. I REQUESTED THE FBO ATTENDANT DRIVE OUT AND STOP THE MOWER DRIVER CLR OF THE RWY AND GET OFF THE TRACTOR UNTIL I HAD DEPARTED. THESE ACTIONS WERE TAKEN AND A NORMAL TKOF AND DEP WERE COMPLETED. THIS WAS THE FIRST TIME THE AIRFIELD WAS BEING MOWED FOR THE YR AND THE MOWER OPERATOR HAD NO RADIO CONTACT WITH ANYONE ON THE FIELD. I FEEL IT SHOULD BE AN ATTN ITEM FOR ALL UNCTLED ARPT MGRS TO FULLY BRIEF ANYONE OPERATING ON THE ARPT WITH REGARD TO RWY AND ARPT MOVEMENTS AND THE HAZARDS THEIR ACTIONS CAN CAUSE.