Abstract: A field experiment was carried to study the effects of organic-inorganic mixed fertilizers on rice yield, nitrogen (N) use efficiency, soil N supply, and soil microbial diversity. Rapeseed cake compost (RCC), pig manure compost (PMC), and Chinese medicine residue compost (MRC) were mixed with chemical N, P and K fertilizers. All the treatments except CK received the same rate of N. The results showed that all N fertilizer application treatments had higher rice yield (79188〖KG-*2〗-〖KG-*7〗94492 kg·hm-2) than the control (69479 kg·hm-2). Compared with that of chemical fertilizers (CF) treatment (79188 kg·hm-2), the yield of the three organic-inorganic mixed fertilizers treatments ranged in 85320〖KG-*2〗-〖KG-*7〗94492 kg·hm-2, and the increment was 77%〖KG-*2〗-〖KG-*7〗193%. Compared with treatment CF, the treatments of organic-inorganic mixed fertilizers were significantly higher in N accumulation, N transportation efficiency, N recovery rate, agronomic N use efficiency, and physiological N use efficiency. These mixed fertilizers treatments promoted rice N uptake and improved soil N supply, and thus, increased N use efficiency, compared with treatments CF and CK. Neighbor joining analysis indicated that soil bacterial communities in the five treatments could be classified into three categories, i.e., CF and CK, PMC and MRC, and RCC, implying that the application of exogenous organic materials could affect soil bacterial communities, while applying chemical fertilizers had little effect on them.

Key words: photosynthate, lag time, pulse labeling, soil respiration.