Brent Kerby (personal communication, 31 August 2008) notes that there is an Isaiah passage where the expression “digged it” occurs without the preposition about. In fact, this passage starts out with virtually the same language as here in Jacob 5:47 (asking what the Lord could have done more to his vineyard), although it refers negatively rather than positively to what the Lord ends up doing to his vineyard:
I will tell you what I will do to my vineyard I will take away the hedge thereof and it shall be eaten up and break down the wall thereof and it shall be trodden down and I will lay it waste it shall not be pruned nor digged but there shall come up briars and thorns
Thus the use of digged without about in Jacob 5:47 is probably intended. In addition, under the verb dig, the Oxford English Dictionary lists examples of this usage without about (meaning ‘to till with a spade’), with citations from 1526 through 1626 under definition 4b, including one that refers to digging and dunging of young plants of a year old (here the accidentals are regularized):
Thus the original decision (in part 2) to accept Joseph Smith’s emendation in Jacob 5:47 will be reversed.
As explained in the following addendum, the verb form become in the subordinate clause “that the trees had become again the natural fruit” should be replaced by brought.
Summary: Restore in Jacob 5:47 the earliest reading without about for the verb dig: “and I have digged it”.