The farmers had suspended their strike at the end of February after a young farmer died during the protest.
To prevent the march, Delhi's borders are heavily barricaded and police have been deployed.
The farmers' protests have restarted even as India is just months away from holding general elections.
Farmers are an important voting bloc in the country and analysts say the federal government of Prime Minister Narendra Modi would not want to antagonise them so close to the polls.
When the farmers' protests first resumed in the beginning of February, the government had held talks with unions to stop them from marching to Delhi from the neighbouring states of Punjab, Haryana and Uttar Pradesh.
Talks with the government broke down at least three times after the authorities could not meet all of their demands.
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