Bacterial communities as indicators of soil health under a continuous cropping system

Abstract

With growing global interest in the improvement of soil quality and the adoption of sustainable land management systems, there is an urgent need to find early indicators to monitor and manage sustainable soil health. Meta‐analyses provide useful information on microbial communities and community‐level molecular characteristics, which can be exploited as ‘biomarker’ indicators of ecosystem processes for soil health evaluation. Lanzhou lily (Lilium davidii var. unicolor) is the only type of sweet edible lily in China, as well as an endemic species with a narrow distribution. Due to its uses as food and in gardening, this lily has an economic value in the Country, particularly in Gansu Province located in the Loess Plateau. This lily is usually cultivated in long‐term continuous monoculture (replanting), resulting in the so‐called consecutive replanting problem (CRP), which is associated with severe soil degradation and significant yield and quality losses. This study was conducted to investigate the bacterial community structure and specific bacterial members related to the lily's CRPs and soil health degradation indicators via next‐generation sequence (NGS) analysis. The bacterial diversity of rhizosphere soil was analyzed by high‐throughput DNA sequencing (Miseq) of samples collected in fields at 0, 3, 6, and 9 replanting years (L0, L3, L6, and L9, respectively). Results showed that long‐term replanting significantly increased soil bacterial abundance and insignificantly changed soil bacterial diversity. However, replanting altered the soil microbial communities where 3–6 years of replanting was a transmission period for change, resulting in a new community structure after 9 years of replanting. Some specific bacterial members were found to be correlated with lily's plant growth, both positively and negatively. Long‐term replanting accumulation of the harbored highly abundant pathogenic bacterial genus Streptomyces and the species Bacillus simplex and depletion of the plant‐beneficial bacteria genera Sphingomonas and Hyphomicrobium are the causes of the lily's CRP under a 0–9 year replanting system. In addition, changes in the soil physiochemical properties contributed to the new structure of bacterial communities, and the phylum Proteobacteria and the genus Sphingomonas could be regarded as potential indicators of sustainable soil management.

Continuous cropping of cut chrysanthemum reduces rhizospheric soil microbial populations, diversity and network complexity

“…3b). Our nding was similar to the results from the Lanzhou lily continuous cropping system, where the microbial community compositions were distinguished into three groups during 9 years of continuously replanting [44]: one group (0-3 years), second group (3-6 years), and third group (6-9 years). In addition, a similar result was gained in the monoculture system of soybean [3].…”

Silicon Fertilizer and Microbial Agents Changed the Bacterial Community in the Consecutive Replant Soil of Lilies

“…In soil with rice-wheat rotation fertilized with straw, bacterial community diversity was significantly negatively correlated with pH [38]. Our previous study showed that soil pH increased during the 0-9 years of the Lanzhou lily cropping system, and soil salinization occurred [39], while the organic content and bacterial richness increased due to the continuous application of organic fertilizers to the soil, solving the lily CRPs under the traditional soil management in this lily production area [15]. Therefore, we concluded that the bacterial community structure in the soil significantly changed mainly due to silicon fertilizer and microbial agents, which prevented an increase in pH and a decrease in organic content.…”

“…Soil bacteria play an important role in nutrient uptake, resistance to soil-borne diseases, and the activation of the plant defense system against pathogens [12][13][14]. We used NGS technology to analyze the bacterial structures in the rhizosphere of the Lanzhou lily under continuous cropping, and we found that the phylum Proteobacteria and the related genus Sphingomonas can be regarded as biomarkers in the system of lily transplantation [15]. Currently, there are many reports showing the role of microbial agents in regulating soil microbial community, but fewer reports focus on the effects of silicon fertilizer on soil microbial community.…”

An optimized method to obtain high-quality RNA from different tissues in Lilium davidii var. unicolor

“…unicolor ), an important economic crop, is the only edible sweet lily in China. It is an endemic species that is only suitable at the altitude of 2000–2600 m, resulting in a narrow distribution in Gansu Province, western China 1 . Bulbs of the L. davidii var .…”