How for where economic problems responsible for Stalin’s decision to replace the NEP in 1928 with the Five-Year Plan?
I believe that to great extent that their was alot of changes
In 1928 the New Economic Policy was replaced with a Five Year Plan. As Soviet industry lagged well behind the Western European states in terms of productivity and quality. The Five Year Plans created targets for all sectors of Industry. These were set and monitored by central government with a view to improving the industrial capacity of the Soviet Union. The Industrial targets involved heavy investment in mining and the extraction of raw materials from Russia's vast interior. This lead to new towns such as Magnitogorsk grew up and large projects such as the Dnieper hydroelectric dam were developed. It required massive movement of workers to sites designated as being primae areas for production of specific items and it meant an end to profit based prodction in factories and on farms. Farming also changed as part of this policy. From 1928 onwards farming was collectivised. This involved closing small holdings and combining them into massive, mechanised farms that were state controled. These should be more efficient, would lead to better education, training and use of technology and were intended to increase productivity and efficiency. Ideologicaly they were also more in line with socialism as the benefits of the new system would be felt by all.

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• Stalin