He also needed to
Control the production. Since the NEP ,the Kulaks (wealthier peasants) had controlled prices of grain, and had hoarded their surplus to ensure that prices stayed high (because high demand and low supply = high prices!).
Stalin needed to ensure that the price of grain was cheap, so workers in the town could afford to buy grain without Stalin having to increase wages. So he needed to destroy the power of the Kulaks to control grain prices. Stalin may also have wanted to destroy the Kulaks for ideological reasons – having a class of ‘agricultural capitalists’ didn’t really fit with Communist ideas!