and it’s essential to keep the two layers of soil (subsoil and topsoil) separate. In order to do this, the lower half of the trench can be dug over in situ. Remove the soil from the upper and ...
The Journal of Education, Vol. 69, No. 24 (1734) (JUNE 17, 1909), p. 663, 667 (2 pages) This item is openly available as part of an Open JSTOR Collection. For terms ...
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