akadamatuti to huyoudo wo mazeru.

Here, と links two nouns and means and.

So:

• 赤玉土 と 腐葉土 = akadama soil and leaf mold / leaf compost

In this sentence, と is making a complete list of the things being mixed.

Because 赤玉土 と 腐葉土 works together as one combined object of the verb 混ぜる.

So the structure is:

• [赤玉土 と 腐葉土] を 混ぜる
• Mix [akadama soil and leaf mold].

Japanese often marks the whole noun phrase once, rather than marking each item separately.

混ぜる is the plain/dictionary form of the verb.

This form can be used in several ways depending on context:

• dictionary form: to mix
• plain non-past: mix / will mix
• instruction style, especially in manuals/recipes/gardening notes: mix

So in a short instruction like this, 混ぜる often feels like a recipe/manual style step.

More polite versions would be:

• 混ぜます
• 混ぜてください = please mix

A stronger command would be something else, such as 混ぜろ, but that is not what we have here.

Yes, but that is completely normal in Japanese.

Japanese often leaves out the subject when it is obvious from context. So this sentence could mean things like:

• Mix akadama soil and leaf mold.
• You mix akadama soil and leaf mold.
• We mix akadama soil and leaf mold.

The exact subject is not stated because the context usually makes it clear.

They are read:

• 赤玉土 = あかだまつち
• 腐葉土 = ふようど

A useful thing to notice is that 土 does not always have the same reading.

For example:

• in 赤玉土, it is つち
• in 腐葉土, it is ど

This is very common in Japanese compounds: kanji can have different readings depending on the word.

Both patterns can exist, but they feel slightly different.

1. 赤玉土 と 腐葉土 を 混ぜる
   This treats akadama soil and leaf mold as one combined set of things to mix.

2. 赤玉土 を 腐葉土 と 混ぜる
   This feels more like mix akadama soil with leaf mold.

So the sentence you have is a straightforward way to say that those two materials are mixed together.

Grammatically, や can also list nouns, but it gives a different nuance.

• と = a complete, specific list
• や = things like A and B; a non-exhaustive list

So:

• 赤玉土 と 腐葉土 = akadama soil and leaf mold specifically
• 赤玉土 や 腐葉土 = things like akadama soil and leaf mold

In an instruction about exactly what to mix, と is the more natural choice.

The spaces are usually added for learners.

Normal Japanese is typically written without spaces:

• 赤玉土と腐葉土を混ぜる。

In beginner materials, spaces are often inserted to make the parts easier to see:

• noun
• particle
• noun
• particle
• verb

So the spaced version is just a learning aid.

Yes. 混ぜる is a transitive verb, so it takes a direct object marked by を.

That is why you get:

• 赤玉土 と 腐葉土 を 混ぜる

The things being mixed are the object.

A related intransitive idea would be something like mix together / become mixed, but that is not the pattern used in this sentence.

It can be a full sentence, but in real life it often sounds like a short instruction, memo, recipe step, or gardening manual note.

That is because:

• the subject is omitted
• the verb is in plain form
• the sentence is short and direct

So it can feel a bit like:

• Mix akadama soil and leaf mold.

This kind of concise style is very common in instructions.