.. .. as opposed to what, an unarmoured Chinese tank?
And what particular model of Chinese armoured tank cos you know the new type 99 weighs 51 tonnes which is a lot more than 37 tonnes.
Maybe they mean the old type 59 which weighed 36 tonnes, possibly 37 with crew and ammunition, but they stopped making those in 1980.
If you are going to use the Chinese armoured tank to illustrate the weight of a lot of potatoes you better make damn sure you know what you're talking about and keep up to date. Don't mess with the Chinese army. One needs to employ constant vigilance to keep up with the fast moving world of Chinese armoured tank technology and whenever they bring a new one out you must go and weigh it and then revise all of your publications in which you have used the Chinese armoured tank as a non-SI unit. These things go out of date so quickly.
This whole idea of expressing the mass of a bunch of spuds in tems of Chinese armoured tanks is fraught with danger. Couldn't they just use tonnes or something?
How big is a hectare anyway, compared to, say, the wingspan of a Russian Ilyushin-76 bomber?