Soil.
Soil. The loose surface material of the earth in which plants grow, in most cases consisting of disintegrated rock with an admixture of organic material and soluble salts.
Source
7 CFR § 330.100
Scoping language
Words used in the singular form in the regulations in this part shall be deemed to impart the plural and vice versa, as the case may demand. For the purposes of this part, unless the context otherwise requires, the following words shall be construed, respectively, to mean: