71,000 bushels is about 0.0000000006 times as big as Halley's Comet.
In other words, it's 0.000000000620 times the size of Halley's Comet, and the size of Halley's Comet is 1,600,000,000 times that amount.
(Comet Halley, officially "1P/Halley") (volume calculated based on 2005 dimensions)
Halley's Comet, the famous comet visible to observers on Earth approximately every 76 years, has a peanut- or potato-shaped nucleus made of rock, dust, ice, and various frozen gasses. The nucleus measures approximately 15 km by 8 km by 8 km, which yields a calculated volume of 110,000,000,000,000.00000000000000000 bushels. The coma of the Comet — the trail of sublimated gasses that give the Comet its visibility — may be up to 100,000 km in length.