Food-chain crops
(4) Food-chain crops means tobacco, crops grown for human consumption, and animal feed for animals whose products are consumed by humans. (5) Incorporated into the soil means the injection of solid waste beneath the surface of the soil or the mixing of solid waste with the surface soil. (6) Pasture crops means crops such as legumes, grasses, grain stubble and stover which are consumed by animals while grazing. (7) pH means the logarithm of the reciprocal of hydrogen ion concentration. (8) Root crops means plants whose edible parts are grown below the surface of the soil. (9) Soil pH is the value obtained by sampling the soil to the depth of cultivation or solid waste placement, whichever is greater, and analyzing by the electrometric method. (Methods of Soil Analysis, Agronomy Monograph No. 9, C.A. Black, ed., American Society of Agronomy, Madison, Wisconsin, pp. 914-926, 1965.)