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To select an eco-friendly nitrogen (N) application level for sugarcane production, soil fertility and soil bacterial diversity under different nitrogen application levels were analyzed. Four levels of urea applications were high Nitrogen (H, 964 kg ha−1), medium Nitrogen (M, 482 kg ha−1), low Nitrogen (L, 96 kg ha−1) and no Nitrogen (CK, 0 kg ha−1) treatments, respectively. The results showed that the soil microbial biomass carbon and phosphorus were altered significantly by CK and L treatments. Moreover, the indexes of soil bacterial richness and diversity in the sugarcane field could be significantly improved by L. At the genus level, SC-I-84, Mycobacterium, Micropepsaceae, Saccharimonadales, Subgroup_2 and Acetobacteraceae were the unique dominant bacteria in the soil with the H treatment. JG30-KF-CM45 and Jatrophihabitans were the unique dominant genera in the M treatment. Subgroup_6, HSB_OF53-F07, Streptomyces, 67–14, SBR1031 and KD4-96 were the unique dominant genera in the L treatment. In contrast, FCPS473, Actinospica, 1921–2, Sinomonas, and Ktedonobacteraceae were the unique dominant genera in the CK treatment. The findings suggest that soil fertility all could be changed by different N application levels, but the most increasing integral effect only could be found in L. Moreover, even though soil bacterial richness could be significantly promoted by the M and H treatments, but soil bacterial diversity could not be significantly improved. On the contrary, soil bacterial diversity and richness all could be improved by L treatment. In addition, higher abundance of unique soil dominant bacteria could be only found in L treatment which compared to the CK, M and H treatments. These findings suggest that the rate of 96 kg ha−1 N application is ecofriendly for sugarcane production in Guangxi.

To elucidate the biological mechanism of yellow rind formation on watermelon, the characteristics of soil bacterial community structure in rhizosphere and endophytic bacteria in stem of yellow rind watermelon were analyzed. Based on high-throughput sequencing technology, plant stem and rhizosphere soil samples, which collected from yellow and green rind watermelons were used in this paper, respectively. The structural characteristics of the endophytic bacteria in stems and soil bacterial communities in rhizospheres of yellow and green rind watermelons were comparative studied. Firstly, significant different proportions of some dominant bacteria and abundances could be detected between yellow and rind watermelons. Meanwhile, although different abundances of endophytic bacteria could be found, but no significant differences were observed between yellow and green rind watermelons. Moreover, Gemmatimonadota, Myxococcota, WPS-2, norank_f_Gemmatimonadaceae and Bradyrhizobium were the soil dominant bacterial genera in rhizosphere of green rind watermelon. All above results suggest that differences of rhizospheric and endophytic bacteria are exactly recruited as “workers” by different watermelon phenotypes relating to rind color formations.