Khanna on the Grand Trunk Road claims the largest grain market in Asia by arrivals. In a good season several lakh tonnes of wheat and paddy pass through it in a few weeks.
The mandi is a physical demonstration of how Punjab's procurement system works: heaps of grain in the open on concrete, arhtiyas' sheds around the edge, government purchase staff, weighmen, labourers, and a queue of trolleys down the highway for kilometres.
It is also a demonstration of the system's weaknesses. Grain sits uncovered, unseasonal rain destroys it, and storage in Punjab has been inadequate for decades. Food Corporation of India stocks stored in the open under tarpaulin have rotted in quantities that have been the subject of Supreme Court comment.
Khanna also holds one of the state's larger steel rolling and bicycle parts industries.
A visitor who wants to understand Punjab's agriculture in one afternoon should stand in the Khanna mandi in late April.
The claim about size is about arrivals in a season rather than turnover, and it is repeated in official material without a source attached. What is not in doubt is that in April and in October the yard cannot hold what comes into it and the overflow stands on the highway.
The labour is on piece rates and is largely migrant, from Bihar and eastern Uttar Pradesh, and the same men come back to the same arhtiya every season. Loading, unloading, cleaning, stitching and stacking are separate rates paid to separate gangs, and none of it appears on any register anywhere.
A market of this size is an institution with its own labour force, its own credit system and its own politics, and none of it has been described in print.