The centre of the stadium has been cleared of cranes and concrete mixers to make way for grounds contractors from Hewitt Sportsturf, according to the Olympic Delivery Authority (ODA).
"Kit has been cleared so work can begin on creating the ground conditions for the track and the turf for the field events," a spokeswoman confirmed. "Ducts and a drainage system will be installed and base layers laid in preparation for laying the turf and track next year."
Hewitt Sportsturf did not comment, but ODA chair John Armitt said surfaces were crucial because the image of the 16ha stadium would be "beamed to billions".
He added: "Only two years ago the stadium site was a flat piece of ground. The venue is now structurally complete and work is progressing on covering the roof. The continuing progress means the stadium is still on track to be completed a whole year before the games."
Minister for sport and the Olympics Hugh Robertson said: "When people think about the Olympic Park, the first image that comes to mind is the stadium."
London 2012 organising committee chair Lord Coe added: "The Olympic stadium will be the centrepiece and it will leave an inspirational legacy."
BUILDING TO DATE
- Thirty-three buildings demolished and more than 800,000 tonnes of soil taken away.
- Landscaping including trees, a green wall and a trial sowing of meadows.
- A 450-tonne cable and net roof structure hoisted into place.