Shekalim1: 2
אָמַר רַבִּי יְהוּדָה: בָּרִאשׁוֹנָה הָיוּ עוֹקְרִין וּמַשְׁלִיכִין לִפְנֵיהֶם. מִשֶּׁרַבּוּ עוֹבְרֵי עֲבֵרָה, הָיוּ עוֹקְרִין וּמַשְׁלִיכִין עַל הַדְּרָכִים. הִתְקִינוּ שֶׁיְּהוּ מַפְקִירִין כָּל הַשָּׂדֶה כֻלָּהּ.
Said R’ Yehudah: At first they would uproot and throw [the kilayim] before them. When the number of transgressors in-creased, they would uproot and throw [the kilayim] upon the roads. [Finally,] they instituted that they declare the entire field ownerless.