Learn Turkish: Her fidanın köküne tam birer tohum gömdük. - We buried exactly one seed into the root of each sapling.

The suffix -er in birer makes it a distributive numeral, meaning "one each". If we just said tam bir tohum, it would mean we buried exactly one seed in total across all the saplings. Birer clarifies that exactly one seed went into each sapling's root.

Can you break down the suffixes in fidanın köküne?

This is a genitive-possessive construction meaning "the sapling's root". Fidan gets the genitive suffix -ın (of the sapling), and kök (root) gets the possessive suffix -ü (its root). Finally, the dative case -e is added because the action of burying is directed into the root, with the buffer consonant -n- linking the two vowels (kök-ü-n-e).

Since we are burying seeds in multiple saplings, why is tohum singular here?

In Turkish, nouns must remain in their singular form when they are preceded by numbers or distributive numerals like birer. So, it is always birer tohum (one seed each), never birer tohumlar.

I thought tam meant "full" or "complete". Why is it translated as "exactly" here?