I 153

4. New Earth or Soil, a Manure for Potatoes.

We have already obſerved that the greateſt crops of potatoes are raifed upon new ſoils; preſuming from this circumſtance, that the uſe of new eartli laid into the drills, would act as a manure. The author of this paper made a trial of it laſt year upon a crop of potatoes planted about the end of June, on a ſpot of ground from which a crop of the early kind had juſt been ſeparated. One of the drills of this late crop was planted without any of the new earth: the effect was very viſible; that where the earth was applied, yielding a luxuriant good crop, nearly double of what was ob- tained from the drills, where none of it was uſed. The ſoil made uſe of in this experiment, was the ſub-ſoil of a part of the ſame garden; which was taken out in the following manner: A trench was dug of eighteen inches deep, and the ſame width. Into this trench the firſt ipading of the earth was thrown, and'the next ſpade-depth of the ſub-ſoil taken out and carried away. In this way the ſurface remains unaltered, and the ground is equally valuable as it was before the removal of the earth: befides, this earth can be reſtored at a future period from the field to which it has been carried, by taking away a part of the ſub-ſoil from it in the ſame manner.

It is worthy of remark, that the practice of taking out the ſub-ſoil may be followed with the ſame ſucceſs for any other crop, as well as potatoes-.

5. Lime as a Manure for Potatoes.

Lime is frequently employed as a manure for potatoes, and, to appear- ance, with conſiderable fucceſs, eſpecially upon new lands or deep heavy loams that have been long under tillage. From ſome obſervations which we have lately made, we are however diſpoſed to think lime an improper manure. The circumſtances which gave riſe to this opinion are as follow:

A piece of ground(deep loam) was well manured with lime and planted with potatoes: when their plants appeared above ground, near three-fourths- of them were curled, while at the ſame time a few drills immediately ad- joining, which had got no lime upon the ſoil, and planted with the ſame ſeed, were entirely free from the diſtemper. This circumſtance artracted notice; and the ſame experiment was repeated next year, with the ſame reſult. Since that time, the author of the preſent memoir has paid par- ticular attention to thoſe ſituations in which the curl is moſt frequent; and he has uniformly found it to prevail moſt in the diſtricts where much. lime or aſh-dung is uſed. He has alſo obſerved, that in thoſe parts where X