Effect of different organic–inorganic mixed fertilizer application on pepper yield and soil microbial properties

A field experiment was carried out to study the effect of organic-inorganic mixed fertilizer application on pepper yield, soil mineral nitrogen, soil microbial biomass carbon and nitrogen and microbial diversity. Rapeseed cake compost (RCC), pig manure compost (PMC) and Chinese medicine residue compost (CMC) were mixed with chemical fertilizers (nitrogen, phosphorus and potassium). All the treatments except the CK received the same rate of nitrogen application. The following results were obtained: 1) All fertilization treatments had higher yields than CK(1700.8 kg/ha). Compared with CF (2451.1 kg/ ha), the pepper yield at the three organic-inorganic mixed fertilizer application treatments ranged from 2851.3–3301.5 kg/ha and the increased percentage was 16.3%–34.7%.2) All organic-inorganic mixed fertilizer treatments could improve the capability of soil nitrogen supply, and increase soil microbial biomass carbon and nitrogen content relative to CF and CK. 3) Eighbor Joining analysis indicated that bacteria in the five treatment soils could be classified into three clusters. Soil bacterial communities of CF and CK belonged to the same cluster, while RCC was the second cluster. The soil bacterial communities of PMC and CMC were in the third cluster. Application of organic fertilizers could alter soil bacterial communities, while the application of CF had little effects on soil bacterial communities.