表示“在农场”，通常用介词on。如：

My brother works on the farm. 我兄弟在农场工作。

We worked on the farm during the autumn. 秋季我们在农场工作。

During the summer vacation they worked on the farm. 暑假期间他们在农场工作。

We’d have come before this, but we’ve been very busy on the farm. 我们本愿意早来，可就是农场非常之忙。

但如果是表示“住在农场”呢？用live on the farm还是live at the farm？