Nikolai deals with the money situation and not only pays off all his debts, but starts buying back all the Rostov estates.
He also gets into farming. What does that mean in Tolstoy-world? It has nothing to do with learning about the soil or the produce, but rather learning about the lives of the serfs and getting to understand things from their point of view.
He’s so into farming that Marya gets a little jealous.
Nikolai goes out and works in the fields every day. And he’s pretty nice to his serfs – their land gets the same resources as his land, they get enough livestock to live well, and so on. It gets to the point where nearby serfs ask him to buy them from their masters.