Fig. 1. Concentrations of aqua regia extractable Cd in 0–20 cm topsoil from BSES (I) and
RSES (II) experimental stations. I: five treatments: CK (unamended control); NPK (fertilizer supplying N, P and K); SNPK (straw and NPK fertilizer); M1NPK (pig manure and
lower rate of NPK fertilizer); and M2NPK (pig manure and higher rate of NPK fertilizer).
II: seven treatments: CK (unamended control); NP (NP fertilizer), NK (NK fertilizer), PK
(PK fertilizer), NPK (NPK fertilizer), OM (pig manure), and ONPK (pig manure and NPK
fertilizer).