NATALYA: What are you talking about? Oxen Meadows are ours, not yours!
LOMOV: No, mine, honoured Natalya Stepanovna.
NATALYA: Well, I never knew that before. How do you make that out?
LOMOV: How? I’m speaking of those Oxen Meadows which are wedged in between your birchwoods and the Burnt Marsh.
NATALYA: Yes, yes... they’re ours.
LOMOV: No, you’re mistaken, honoured Natalya Stepanovna, they’re mine.
NATALYA: Just think, Ivan Vassilevitch! How long have they been yours?
LOMOV: How long? As long as I can remember.
NATALYA: Really, you won’t get me to believe that!
Natalya was shocked to hear what Lomov had told her. She claimed Oxen Meadows to be her family property and not Lomov's. Lomov, on the other hand, asserted ownership of Oxen Meadows, and this property dispute was the first cause of their argument.
Natalya says to Lomov that she wasn't aware of it and asked him to explain how he claims it belonged to him. So, to be clear, Lomov specifies the particular Oxen Meadows he is referring to as being those tucked in between birchwoods and the Burnt Marsh, to which Natalya confirmed that she was also talking about the same Oxen meadows. However, Lomov asserted his ownership of the land once more and informed Natalya that she had been incorrect in believing it to be her property.
Natalya couldn't accept Lomov's claim and asked him how long Oxen Meadows had been his, to which Lomov replied that Oxen Meadows had been his for a long time as he remembered. But Natalya remarked that she couldn't believe it as all these days she believed that Oxen Meadows was her family property.
National Council of Educational Research and Training (2007). The Proposal - Anton Chekov (pp. 142-161). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.