Learn Turkish: İyi tarlanın verimi düşmez. - A good field's yield does not drop.

düşmez is the negative form of the aorist (simple present) tense for the 3rd person singular. We use the aorist here instead of the present continuous (düşmüyor) because this sentence states a general, timeless fact about good fields, rather than describing something happening right now. The suffix -mez attaches directly to the verb root düş-.

What is the grammatical connection between tarlanın and verimi?

This is a genitive-possessive noun phrase, meaning "the field's yield". The word tarla (field) gets the genitive suffix -nın (the field's), and verim (yield) gets the 3rd person possessive suffix -i to show that it belongs to the field.

Does iyi (good) describe the field or the yield?

It describes the field. Because iyi comes directly before tarlanın, it modifies the field. If we wanted to say "The field's good yield", we would place the adjective right before the second word: Tarlanın iyi verimi.

Wait, doesn't the verb düşmek usually mean "to fall"?

Yes, its literal meaning is "to fall" (like falling to the ground). However, just like in English, it is frequently used to talk about amounts, numbers, or quality "dropping" or decreasing, which is why it pairs perfectly with verim (yield) in this sentence.