Abstract: This experiment was conducted to investigate the effects of different fertilization regimes on soil microbial biomass carbon (SMBC), nitrogen (SMBN) and enzyme activities in a maize-soybean rotation system. There were seven treatments: (1) no fertilizer input (CK); (2) manure alone 7.5 t·hm^-2 (M1); (3) manure alone 15 t·hm^-2 (M2); (4) manure alone 22.5t·hm^-2 (M3); (5) chemical fertilizer (N 160 kg·hm^-2+P₂O₅ 75 kg·hm^-2+K₂O 75 kg·hm^-2) (T1); (6) manure 7.5 t·hm^-2 plus chemical fertilizer (N 81 kg·hm^-2+P₂O₅ 0kg·hm^-2+K₂O 67 kg·hm^-2) (T2); (7) manure 15 t·hm^-2 plus chemical fertilizer (N 120 kg·hm^-2+P₂O₅ 7 kg·hm^-2+K₂O 71 kg·hm^-2) (T3). Soil samples in 0-20 cm depth were collected in different growth stages and SMBC, SMBN, activities of soil invertase, catalase and urease were measured. There were significant differences in SMBC and SMBN among different treatments. Compared with M1 and M2 (on average), SMBC in T2 and T3 treatments increased by 32% and 21%, and SMBN increased by 38% and 28% at mature stage, respectively. Compared with that at maize mature stage, SMBC at soybean mature stage increased by 13%-51%, and SMBN increased by 85%-174%. T3 treatment had most significant effects on soil invertase activity in the different growth stages. The combined applications of organic and inorganic fertilizers- had greater effects on the activities of soil catalase and urease. Relative to the corn field, SMBC, SMBN and enzyme activities were increased with different degrees in the soybean field. SMBC, SMBN and enzyme activities were closely related to soil organic matter, nitrate, ammonium, available P and K contents in different treatments. Organic fertilizer application or combined application with chemical fertilizer could improve soil nutrients, urease activity, SMBC and SMBN, but no significant correlation was observed between catalase activity and fertilization level.

Key words: temperature sensitivity, sand dune., soil temperature, soil moisture, source sink relationship