Sentence below is missing at least one‘ add the cost to be where they are needed using this proofreading mark house me and year is used as fertilizer on farms all across America

This question is incomplete, here´s the complete question.  

The sentence below is missing at least one apostrophe. Add the apostrophe where needed.

Cows manure is used as fertilizer on farms all across America.

Cow´s manure is used as fertilizer on farms all across America.

Explanation:

The apostrophe is used for two very different purposes: contractions and possession.

Contractions are the most frequent use of apostrophes. We know there´s a contraction when a noun or pronoun is merged with a verb, and the apostrophe often substitutes a dropped letter. For example: "She's shy."

In this case (cow´s) the apostrophe is a possessive one. Another example would be: "The doctor's patient"

the words “strangest” and “unusual” suggest that the narrator is about to tell the story of an odd or puzzling group of people.