Компост і добриво покращують ґрунт.

Because the subject is actually two things: компост і добриво (compost and fertilizer). In Ukrainian, when two singular nouns are joined by і (and), the verb normally goes in the plural.

• компост = singular
• добриво = singular
• together: компост і добриво = plural idea

So:

• покращує = improves (singular)
• покращують = improve (plural)

They are in the nominative case, because they are the subject of the sentence — the things doing the action.

• компост = nominative singular
• добриво = nominative singular

In dictionaries, nouns are usually listed in this form.

ґрунт is in the accusative case, because it is the direct object — the thing being improved.

Here, ґрунт looks the same as the nominative form. That is very common for inanimate masculine nouns in Ukrainian:

• nominative: ґрунт
• accusative: ґрунт

So even though the form does not change, its role in the sentence is different.

Yes, і usually means and.

In this sentence:

• компост і добриво = compost and fertilizer

Ukrainian also has й, which can also mean and. Very often і and й are chosen for sound and flow rather than meaning. The meaning is normally the same.

The noun добриво is a neuter noun, which you can often recognize from the ending -о.

So:

• добриво = neuter singular

This matters for agreement in other contexts, for example with adjectives:

• органічне добриво = organic fertilizer

Yes. Компост is a masculine noun.

A common clue is that many masculine nouns in Ukrainian end in a consonant in the dictionary form:

• компост
• ґрунт

So in this sentence:

• компост = masculine
• добриво = neuter
• together they still take a plural verb

Yes. Ukrainian word order is more flexible than English word order because case endings help show grammatical roles.

The neutral version is:

• Компост і добриво покращують ґрунт.

But other orders are possible for emphasis, for example:

• Ґрунт покращують компост і добриво.
• Покращують ґрунт компост і добриво.

These all express roughly the same basic idea, but the emphasis changes.

Yes. Покращують is present tense, third person plural:

• вони покращують = they improve

Here the subject is not a pronoun like вони (they), but the noun phrase компост і добриво, so the plural verb form is still used.

The infinitive is покращувати or покращити, depending on aspect.

• покращувати = to be improving / to improve (imperfective)
• покращити = to improve / make better (perfective)

In this sentence, покращують is an imperfective present form, which fits a general fact or repeated action:

• Компост і добриво покращують ґрунт.
• Compost and fertilizer improve soil.

The letter ґ represents a hard g sound, like the g in go.

So ґрунт is roughly pronounced like grunt with a Ukrainian vowel quality.
This is different from г, which in Ukrainian is usually pronounced more like a voiced h sound.

So:

• ґ = hard g
• г = softer, breathier sound

This difference is important because Ukrainian uses both letters.

A helpful way to learn the sentence is with stress marked:

• компо́ст
• добри́во
• покра́щують
• ґрунт

So the whole sentence is:

Компо́ст і добри́во покра́щують ґрунт.

Stress is important in Ukrainian because it is not always predictable.

Normally, no — not in standard neutral speech. To say compost and fertilizer, you should use і:

• компост і добриво

Without і, it would sound incomplete or unnatural in this simple sentence.

Its basic meaning is soil or ground, especially in agricultural, gardening, or scientific contexts.

Depending on context, ґрунт can also mean:

• soil
• earth
• ground
• sometimes foundation/basis in more abstract uses

But in this sentence, it clearly means soil.

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

So:

• Компост can mean compost
• добриво can mean fertilizer or the fertilizer
• ґрунт can mean soil or the soil

The exact interpretation depends on context.

Yes. The present tense in Ukrainian, just like in English, can express a general fact.

So this sentence is naturally understood as:

• Compost and fertilizer improve soil
  rather than only
• Compost and fertilizer are improving the soil right now

That makes it sound like a general statement about gardening or agriculture.