the National Natural Science Foundation of China (No.40321101);the Ministry of Science and Technology of China (No.2005CB121105) ;the Knowledge Innovation Program of the Chinese Academy of Sciences(Nos.KZCX1-SW-19 and KZCX2-YW-408).
An experiment with seven N, P, K-fertilizer treatments, i.e., control (no fertilizer), NP, NK, PK, NPK, NP2K, and NPK2 where P2 and K2 indicate double amounts of P and K fertilizers respectively, was conducted to exam...