O adubo é capaz de melhorar a colheita.

Portuguese often uses the definite article more than English does.

So o adubo can mean:

• the fertilizer in a specific context, or
• fertilizer in a general sense

In English, we often drop the article in general statements, but in Portuguese it is very common to keep it.

So O adubo é capaz de melhorar a colheita sounds natural, even if the idea is general.

Because the nouns have different grammatical genders:

• adubo is masculine → o adubo
• colheita is feminine → a colheita

This is grammatical gender, not biological sex. It affects the article and sometimes other words connected to the noun.

Adubo means fertilizer, manure, or more generally a substance used to enrich the soil and help plants grow better.

In European Portuguese, adubo is a very normal everyday word. You may also see fertilizante, which is a bit more technical or formal.

In this sentence, colheita usually means the harvest or the crop yield.

So the sentence is talking about improving the result of agriculture, not the physical action of harvesting.

Depending on context, colheita can refer to:

• the harvest itself
• the amount produced
• the agricultural outcome

Here, improve the harvest / increase yield is the most natural idea.

Yes. Ser capaz de + infinitive is a very common structure in Portuguese.

It means:

• to be capable of
• to be able to
• sometimes to have the potential to

So:

• é capaz de melhorar = is capable of improving

This is a standard pattern:

• sou capaz de
• és capaz de
• é capaz de
• somos capazes de
• são capazes de

Because capaz normally takes de before another verb.

The pattern is:

ser capaz de + infinitive

Examples:

• Ela é capaz de ajudar. = She is capable of helping.
• Somos capazes de resolver isso. = We are capable of solving that.
• O adubo é capaz de melhorar a colheita.

So the de is required by the expression.

Because after é capaz de, the next verb stays in the infinitive.

So:

• é capaz de melhorar
• é capaz de aumentar
• é capaz de reduzir

This works much like English capable of improving, except Portuguese uses de + infinitive instead of of + -ing.

Yes, absolutely.

O adubo pode melhorar a colheita is a natural alternative and means The fertilizer can improve the harvest.

The difference is mainly nuance:

• pode melhorar = can improve
• é capaz de melhorar = is capable of improving / has the capacity to improve

É capaz de can sound slightly more formal, descriptive, or emphatic about ability/potential.

Yes.

É is the 3rd person singular present of ser:

• eu sou
• tu és
• ele/ela/você é

Here it matches o adubo, which is singular:

• O adubo é...

The sentence is in the present tense because it expresses a general fact or general possibility.

It can do either, depending on context.

Without extra context, it can be understood as a general statement:

• Fertilizer is capable of improving the harvest

But if people are already talking about a particular fertilizer, it can also mean:

• That/The fertilizer is capable of improving the harvest

Portuguese often allows this kind of flexibility.

Yes. Capaz agrees in number, but not usually in gender in this use.

Examples:

• O adubo é capaz de ajudar.
• Os adubos são capazes de ajudar.

So:

• singular → capaz
• plural → capazes

With adubo in the singular, capaz stays singular.

The tricky part is lh.

In European Portuguese, lh represents a sound similar to the lli in some pronunciations of million, but it is not exactly the same as any standard English sound.

So colheita sounds approximately like:

co-lyei-ta
or more closely in European Portuguese: ku-LHAY-ta

A few pronunciation points:

• lh is one single consonant sound
• ei here sounds like a diphthong, roughly like ay
• the stress is on hei: colHEIta

Yes. This is the standard, neutral word order:

O adubo + é capaz de melhorar + a colheita

That is:

• subject: O adubo
• verb phrase: é capaz de melhorar
• object: a colheita

It is the most natural order for a straightforward statement.

Yes, you could.

• O adubo é capaz de melhorar a colheita.
• O fertilizante é capaz de melhorar a colheita.

Both are correct.

The difference is mostly register and nuance:

• adubo = more common everyday word
• fertilizante = more technical/scientific sounding

In many practical contexts, adubo is the more natural choice.

It can mean either, depending on context.

Melhorar a colheita may suggest:

• producing more
• producing better-quality crops
• improving the overall agricultural result

So the phrase is broad. If you want to be more specific, Portuguese can say things like:

• aumentar a produção = increase production
• melhorar a qualidade da colheita = improve the quality of the harvest
• aumentar o rendimento = increase yield