Commentary for Bava Batra 55:2
שדה הבעל חזקתה שלש שנים ואינן מיום ליום
FROM DAY TO DAY.<span class="x" onmousemove="('comment',' I.e., from any date in one year to a corresponding date three years later. The reason for this regulation is discussed in the Gemara. ');"><sup>4</sup></span> A PRESUMPTIVE TITLE TO A NON-IRRIGATED FIELD IS CONFERRED BY THREE YEARS' POSSESSION NOT RECKONED FROM DAY TO DAY.<span class="x" onmousemove="('comment',' As explained in what follows. ');"><sup>5</sup></span> R. ISHMAEL SAYS: IT IS SUFFICIENT TO HAVE THREE MONTHS IN THE FIRST YEAR, THREE MONTHS IN THE LAST AND TWELVE IN THE MIDDLE,<span class="x" onmousemove="('comment',' Because some crops are sown in the last three months of the year and some in the first three, and to crop the field at these times is equivalent to possessing it for a year. ');"><sup>6</sup></span>