The demonstrators say they have not only been left behind by India's recent economic boom, but have also suffered directly with many forced from their land to make way for government-backed economic projects.
"Forty percent of Indians are now landless and 23 per cent of them are in abject poverty," march organiser Puthan Vithal Rajgopal told AFP.
"Such conditions have bred Maoist insurgency in 172 of India's 600 districts and farmers are killing themselves in 100 other districts. So we want to ask the government, 'Where are the fruits of the reforms in these districts?'"
In an effort to attract foreign investment India has set up a series of Special Economic Zones offering companies tax breaks to set up business and factories.
But critics say farmers often fall victim when they are forced from their land or cheated on its value when land is acquired for government projects.
|More than 25,000 protesters joined the |
month-long march to Delhi [EPA]
India's vague property laws and endemic corruption are also blamed for the plight of Indian farmers where they are strong-armed off their land by powerful local landowners.
A protester, Vishwas Prasad, told the NDTV news channel: "When these landowners see that someone strong is coming up to fight for his land rights they get them murdered."
On Sunday police in Nandigram in the state of West Bengal said four people had been killed in a clash between farmers and government supporters over land seizures.
Farmers in the area have fiercely resisted efforts by authorities to force land sales at cheap rates so that an industrial zone can be set up.
The latest deaths bring to at least 29 the number of people killed in Nandigram since a wave of clashes broke out in January over the proposed development.