The procurement is being undertaken on behalf of the government to serve the dual purpose of ensuring better price to farmers during peak arrival and storing the commodity for later disposal in the market when retail prices spike.
"The arrival of rabi crop is picking up and even the moisture content is good. So, we will begin the procurement next week," Chadha said.
About 25,000 tonne will be purchased mainly from Lasalgaon, Asia's biggest onion market, as well as Pimpalgaon mandi in Nashik district.
Nafed (National Agricultural Cooperative Federation of India) will store 5,000 tonne in its unit, while the rest will be kept in hired storage godowns in and around these two mandis, he added.
Chadha said the stored onions will be disposed of after 2-3 months as per the government's directions.
At present, onion is sold at Rs 7-8 per kg at Lasalgaon mandi and the prices are expected to show a downtrend once the arrival peaks in the coming weeks.
Rabi onion contributes 65 per cent of the country's total output, which is estimated to be 4.5 per cent lower at 21.4 million tonne in the 2017-18 crop year (July-June) when compared with last year, as per official data.