The Lions captain's six-and-a-quarter-hour 179 out of 433 for seven is his second-lowest score so far in his prolific start to the summer.
With back-to-back Test matches at Lord's and then his home ground at Headingley to come, it is therefore conceivable that Root could yet become the first Englishman in 75 years - and only the sixth ever - to pass 1,000 runs by the end of May.
The last batsman to achieve the feat in an English season was Zimbabwe-born Graeme Hick, in 1988, and new Test opener Nick Compton had an agonising near miss just last year.
Root moved past 150 in the same over his fifth-wicket partner Jonny Bairstow (68) reached his half-century with an inside-edge past leg-stump for four off Trent Boult.
Bairstow eventually fell lbw when Boult (three for 86) got enough movement back in from over the wicket but joined by Ravi Bopara, Root still looked hungry for more runs until Doug Bracewell got through his forward-defence to hit off-stump and at last end a 276-ball innings which had contained 25 fours and a six.
Root's only significant blemish came two days ago in this rain-wrecked contest when he was put down at second slip by Kiwi captain Brendon McCullum off Bracewell on 23.
Under increasingly cloudy skies and with more forecast rain apparently imminent, there was precious little possibility of anything other than a stalemate here at some point.
By lunch, the Lions were 148 in front and - should the bad weather stay away - had the obvious opportunity to put the tourists under a little pressure in their second innings.
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