First off, it is not Nathan Radley who leaves things in the tree, it is actually Boo, or Arthur Radley who leaves presents in the tree for Scout and Jem. Second, the book is called TO Kill a MockingBird, not How To Kill a Mockingbird. But getting to the point, Nathan Radley wants to keep Boo's interactions with the kids to a minimum, so he fills the hole in the tree so Boo cannot leave anymore presents for the children. They catch him doing it, and he claims the tree is sick, and that you should fill them with cement when they are sick. Boo leaves the presents for the children because he doesn't want to leave his house because he wants to be left alone, so at night he puts the presents he has made or gathered, and puts them in the tree for the children to enjoy.
Mr. Nathan Radley fills the knothole with cement in order to prevent the children from receiving any more gifts from Boo Radley. This action is seen as a way to cut off the relationship between Boo and the Finch children.
To keep Boo from leaving things in the tree for Scout and Jem
this happens in chapter 7 and is discussed on page 62 (depending on your version)
You can look at this in many different ways but I think it is because he does not what Boo to contact the children.
He fills it with cement and jem is upset because this was his only connection to Nathan Radleys brother Arthur Radley otherwise known as Boo Radley.
Nathan Radley
he fills it with cement
Mr. Nathan Radley filled the knothole in the tree with cement.
Nathan Radley, Boo's older brother
Scout finds the gifts in the knothole in Chapter 7 of "To Kill a Mockingbird."
In "To Kill a Mockingbird," the knothole in the tree is cemented up by Nathan Radley, Boo Radley's brother, as a way to prevent Boo from communicating with the children. This action symbolizes the Radley family's attempt to isolate Boo from the outside world and maintain their reclusive lifestyle.
The person who closes up the knothole in "To Kill a Mockingbird" is Nathan Radley, Boo Radley's older brother. He fills it with cement to prevent communication between the kids and Boo, as he believes it is leading to trouble.
The knothole incident in "To Kill a Mockingbird" occurs in Chapter 7 when Scout and Jem find gifts left in a knothole of a tree near the Radley house. This marks the beginning of their mysterious exchanges with Boo Radley.
Boo Radley
Arthur's brother in 'To Kill a Mockingbird' is Nathan Radley.
In "To Kill a Mockingbird," the brother of Boo (Arthur) Radley is Nathan Radley. Nathan is portrayed as a stern and reclusive character who is protective of Boo.
Nathan Radley, Boo Radley's brother filled the knothole with cement. When Jem and Scout asked him why he was doing this he told them that his tree was dying and filling the knothole with cement would keep it from dying. Scout and Jem went and asked Atticus if he thought the tree looked like it was dying and he said it looked perfectly healthy.
No one special.
Mr. Nathan Radley is a character in "To Kill a Mockingbird" who is the reclusive and strict older brother of Boo Radley. He is known for sealing up the knothole in the tree, where Boo leaves gifts for Scout and Jem. Nathan also plays a role in the climax of the novel when he shoots at what he believes is an intruder in his yard, but ends up hitting Mr. Ewell instead.
The tree with a knothole in "To Kill a Mockingbird" symbolizes hidden treasures and acts as a place where Boo Radley can subtly communicate with Scout and Jem. It also represents empathy, understanding, and the innocence of childhood.