This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This operation is done with the spade or the fork. It is a much better way of turning up the soil than with the plough. Not only does the spade or fork go deeper, but the soil is turned over more completely, and the clods are broken down into much finer particles. An expert workman will dig from 8 to 15 rods (about 240 to 450 sq. yd.) in a day, according to the nature of the soil. The cost of digging 1 ac. of ground 1 ft. deep will vary from 40s. to 55s., more or less according to the state of the soil and the rate of wages in different parts of the Kingdom; and it will take one man from eleven to twenty days to perform the work properly, and turning over from 70 to 120 tons of soil each day.
Digging consists in opening a trench one spit deep, the full depth of the spade or the fork, and filling it with soil adjacent after lifting and turning completely upside down.