Responsa for Shabbat 146:3
תנא הזורע והזומר והנוטע והמבריך והמרכיב כולן מלאכה אחת הן מאי קמ"ל הא קמ"ל] העושה מלאכות הרבה מעין מלאכה אחת אינו חייב אלא אחת א"ר אחא א"ר חייא בר אשי א"ר אמי זומר חייב משום נוטע והנוטע והמבריך והמרכיב חייב משום זורע משום זורע אין משום נוטע לא אימא אף משום זורע
and grafting are all one labour. What does this inform us? — This: that if one performs many labours of the same nature, he is liable only to one [sacrifice]. R. Abba<span class="x" onmousemove="('comment',' So text as amended. ');"><sup>4</sup></span> said in the name of R. Hiyya b. Ashi in R. Ammi's name: He who prunes is culpable on account of planting, while he who plants, bends [the vine], or grafts is culpable on account of sowing. On account of sowing only but not on account of planting?<span class="x" onmousemove="('comment',' Surely bending and grafting are forms of planting? — Planting and sowing are identical, the former applying to trees and the latter to cereals. ');"><sup>5</sup></span>
Teshuvot Maharam
A. In city property digging is not considered a valid act of possession. Likewise A did not acquire any rights to window lights since a Gentile does not renounce his rights to his property before he receives the money, and the Gentile's property was, therefore, not (res nullis) ownerless. However, before paying money to the Gentile, let B perform a valid act of possession (such as locking a door, fixing or breaking part of the fence, etc.); otherwise A will acquire rights to window lights during the interval between the paying of the money and B's taking formal possession, since during such interval the Gentile's property will be res nullis.
SOURCES: Cr. 63–64; Pr. 28–29; L. 338; Mord. ibid.
Teshuvot Maharam
A. In city property digging is not considered a valid act of possession. Likewise A did not acquire any rights to window lights since a Gentile does not renounce his rights to his property before he receives the money, and the Gentile's property was, therefore, not (res nullis) ownerless. However, before paying money to the Gentile, let B perform a valid act of possession (such as locking a door, fixing or breaking part of the fence, etc.); otherwise A will acquire rights to window lights during the interval between the paying of the money and B's taking formal possession, since during such interval the Gentile's property will be res nullis.
SOURCES: Cr. 63–64; Pr. 28–29; L. 338; Mord. ibid.