The seven fertilizer treatments were (1–3) balanced fertilization
with application of nitrogen (N), phosphorus (P) and potassium (K) including organic compost
(OM), half organic compost plus half chemical fertilizer (1/2OM), and pure chemical
NPK fertilizer (NPK); (4–6) unbalanced chemical fertilization without application of one of
the major elements including NP fertilizer (NP), PK fertilizer (PK), and NK fertilizer (NK); and
(7) an unamended control (CK).