Kompost je v kompostéru.

Because v here expresses location, and after v Czech normally uses the locative case.

So:

• base form: kompostér
• after v: v kompostéru

This is a normal pattern for many masculine nouns. The noun kompostér is masculine inanimate, and its singular locative form is kompostéru.

So the sentence structure is:

• Kompost = subject, in the nominative
• je = is
• v kompostéru = in the compost bin, with kompostéru in the locative

• Kompost is in the nominative because it is the subject of the sentence.
• kompostéru is in the locative because it follows v and describes where something is.

So:

• Kompost → nominative singular
• v kompostéru → prepositional phrase with locative singular

Not always, but very often.

With v, there are two main possibilities:

• location → usually locative
• movement into something → usually accusative

In this sentence, the compost is already located inside the bin, so Czech uses the locative:

• v kompostéru = inside the compost bin

Compare:

• Kompost je v kompostéru. = location
• Dám to do kompostéru. = movement into the compost bin

So here, v is part of a location phrase, which is why kompostéru is in the locative.

Czech often omits to be in some informal contexts, especially in the present tense, but in a normal full sentence like this, je is standard and natural.

• Kompost je v kompostéru. = normal complete sentence

If you removed je, the sentence would sound incomplete in standard Czech.

So although Czech can sometimes drop forms of to be in colloquial speech or headlines, here je is the expected form.

Yes. Czech word order is quite flexible because the case endings show the grammatical roles.

This sentence could also be:

• V kompostéru je kompost.

Both versions are grammatical, but the emphasis changes a little:

• Kompost je v kompostéru. → focuses first on kompost
• V kompostéru je kompost. → focuses first on the location

English usually relies much more on fixed word order than Czech does.

They are related but not the same word:

• kompost = compost
• kompostér = compost bin / composter

In the sentence:

• Kompost is the material
• kompostéru comes from kompostér, the container

This kind of related pair is common in Czech, where one noun names the thing and another names the device or container associated with it.

Because Czech does not have articles like English a/an and the.

So Kompost je v kompostéru can correspond to English with or without an article depending on context.

Czech usually expresses definiteness through context rather than with a special word.

That means learners often need to get used to sentences that feel “article-less” compared with English.

A rough pronunciation guide is:

• kom-posté-ru

A few useful points:

• é is a long e sound
• the stress in Czech is usually on the first syllable: KOMpostéru
• the final u is pronounced clearly, not reduced like English unstressed vowels often are

Also, in normal speech, v before a voiceless consonant like k is often pronounced more like f, so v kompostéru may sound roughly like f kompostéru.

Yes, it is a fairly common pattern for masculine inanimate nouns, especially many nouns ending in a consonant.

For this noun:

• nominative singular: kompostér
• locative singular: kompostéru

You will often see masculine nouns in the locative singular ending in -u or -ě/-e, depending on the noun.

So this sentence is a useful example of an important general rule: after a preposition of location, a noun often changes form.

No, not with the intended meaning here.

• kompost means the compost itself
• kompostér means the compost bin

So v kompostě would mean in the compost, not in the compost bin.

That is a different noun and a different idea.

The sentence needs v kompostéru because it refers to the container, not the compost material itself.