India, April 9 -- KANPUR In a stark symbol of agricultural distress, a few farmers across Uttar Pradesh's potato belt are driving tractors over their standing crops and abandoning cold storage stocks. A severe price crash has inverted the economics of farming: it now costs more to dig, bag and transport potatoes to the mandi than the market is willing to pay.

Farmer Amarjeet of Nadsaa village recently made a grim calculation. Realising the math was entirely against him, he destroyed two bighas of his potato crop rather than take it to market. A few kilometers away in Bharatnagar, Shabban Khan walked away from five bighas worth of potatoes sitting in cold storage, opting to plough his field over instead.

Across the belt stretching from K...