Saman ıslanınca çuvala koymak zor oluyor.

-ınca / -ince / -unca / -ünce is a common Turkish ending that means when, once, or sometimes after.

So:

• ıslanmak = to get wet
• ıslan-ınca = when it gets wet / once it gets wet

In this sentence, Saman ıslanınca... means When the hay gets wet...

This form is often called a converb: it links one action or situation to another without making a full separate clause with a word like when.

Because ıslanmak means to get wet / become wet, while ıslatmak means to wet something.

So:

• saman ıslanıyor = the hay is getting wet
• biri samanı ıslatıyor = someone is wetting the hay

In your sentence, the hay is simply undergoing a change of state, so ıslanmak is the natural choice.

Because saman is the subject of ıslanınca, not a definite direct object.

• saman = hay
• samanı = the hay, as a definite direct object

In Saman ıslanınca, the meaning is when hay gets wet or when the hay gets wet, so the plain form saman is correct.

If you used samanı here, it would sound like the hay is the object of another verb, which is not what is happening in this part of the sentence.

The object is understood from context: it is the hay.

Turkish often leaves out objects if they are already clear. So the sentence does not need to repeat samanı.

An expanded version would be:

• Saman ıslanınca, samanı çuvala koymak zor oluyor.

That is grammatical, but repeating saman is less natural here because the listener already knows what is being put into the sack.

So Turkish simply says:

• ... çuvala koymak ...

and the listener understands putting the hay into the sack.

Because koymak usually takes the dative case for the destination.

• çuval = sack / bag
• çuvala = into the sack / to the sack
• çuvalda = in the sack
• çuvalı = the sack, as a direct object

So:

• çuvala koymak = to put into the sack
• çuvalda would describe location, not movement
• çuvalı koymak would mean to put the sack somewhere

This is the same pattern you see in many Turkish verbs of movement toward a place.

Because the whole phrase çuvala koymak is functioning like putting it into the sack in English.

Turkish often uses the infinitive -mak / -mek to talk about an action as an idea or activity:

• yüzmek = swimming / to swim
• okumak = reading / to read
• çuvala koymak = putting into the sack / to put into the sack

Here, the subject of zor oluyor is not a person but the action itself:

• çuvala koymak zor oluyor = putting it into the sack becomes hard / is hard

Oluyor adds the idea of becoming or turning out to be difficult.

So:

• zor = hard / difficult
• zor oluyor = becomes hard / is difficult in practice

In this sentence, the meaning is that once the hay gets wet, the task of putting it into the sack is no longer easy; it ends up being difficult.

You may also hear:

• Saman ıslanınca çuvala koymak zor.
• Saman ıslanınca çuvala koymak zor olur.

All are possible, but they differ slightly:

• zor = more blunt, condensed
• zor olur = more general, like a rule
• zor oluyor = very natural for describing what happens in such a situation

In Turkish, the present continuous -yor is often used more broadly than English learners first expect.

It can describe:

• something happening now
• a habitual situation
• a generally true practical observation
• what tends to happen under certain conditions

So zor oluyor here does not necessarily mean right now at this moment. It can also mean it tends to be difficult / it becomes difficult in that situation.

This is very natural Turkish.

Yes, Turkish word order is flexible, but the given order is the most natural.

The sentence begins with the condition/time part:

• Saman ıslanınca = when the hay gets wet

Then comes the main statement:

• çuvala koymak zor oluyor = putting it into the sack becomes difficult

This order is very common: condition first, result second.

You could rearrange it for emphasis, for example:

• Çuvala koymak, saman ıslanınca zor oluyor.

But the original version sounds smoother and more neutral.

Because Turkish often omits pronouns and objects when they are obvious from context.

English usually needs it:

• When the hay gets wet, putting it into the sack is hard.

But Turkish can simply say:

• Saman ıslanınca çuvala koymak zor oluyor.

The listener automatically understands that the thing being put into the sack is the hay.

This kind of omission is very common and very natural in Turkish.

Not always. It often means when, but depending on context it can also feel like:

• once
• after
• whenever

For example, in this sentence, when is the best English choice. But in other sentences, once or after may sound better.

So it is best to think of -ınca as expressing a time relationship, and then choose the most natural English wording from context.