10 or 12 mitzvos

The Yerushalmi in Meseches Challah (Perek 1 Hl.6) says, a person is Mekayam
10 Mitzvohs before he can eat bread. The Yerushalmi enumerates them as
follows.
לא תחרוש שור וחמור (1

בל תזרע (כלאים) (2

בל תחסום (שור בדישו) (3

לקט (4

שכחה (5

פיאה (6

תרומה (7

מעשר ראשון (8

מעשר שני (9

חלה (10

The Tur (O.Ch. 167) writes, "A person when making Hamotzie

should place his two hands,10 fingers on the bread , for
the 10 Mitzvohs that is done with the bread.

The Tur* enumerates the same 10 Mitzvohs of the Yerushalmi
with one exception. Instead of בל תחסום he replaces
it with   ביכורים
There actually is one** more Mitzvah,  תרומת מעשר.
If we add , תרומת מעשרand    ביכוריםwe end up with
12 Mitzvos.
It is possible, this to be the reason why, the Yerushalmi
and the Tur, both, mention placing the two hands and the ten
fingers. (adds up to 12).

We still need to understand why they only count 10
Mitzvos when there are 12 Mitzvos. (I have no answer)

*The Pirush HaTur Al HaTorah enumerates like the
Yerushalmi (בל תחסום and not ביכורים)
**  we don’t count מעשר עני,  because it is either a year

of  מעשר שני or a year of מעשר עני and not both.