scholarly journals Cover Crop Species Composition Alters the Soil Bacterial Community in a Continuous Pepper Cropping System

2022 ◽  
Vol 12 ◽  
Author(s):  
Huan Gao ◽  
Gangming Tian ◽  
Muhammad Khashi u Rahman ◽  
Fengzhi Wu

Cover crops can improve soil biological health and alter the composition of soil microbial communities in agricultural systems. However, the effects of diversified cover crops on soil microbial communities in continuous cropping systems are unclear. Here, using different soil biochemical analysis, quantitative PCR and 16S rRNA amplicon sequencing, we investigated the effects of cover crops, alone or in mixture, on soil physicochemical properties in 2019 and 2020, and soil bacterial communities in 2020 in a continuous pepper cropping system. A field trial was established before pepper planting and eight treatments were included: fallow (no cover crop; CK); three sole cover crop treatments: wheat (Triticum aestivum L.; W), faba bean (Vicia faba L.; B), and wild rocket (Diplotaxis tenuifolia; R); and four mixed treatments: wheat + wild rocket (WR), wheat + faba bean (WB), wild rocket + faba bean (RB), and wheat + wild rocket + faba bean (WRB). The pepper yield was increased in the WR and WB in 2019 and 2020, and in the WRB in 2020. Cover crops increased the soil pH, but decreased the concentrations of NH4+ and available phosphorus. Bacterial abundance was increased by cover crop treatments, and community structure was altered in the W, WB, and WRB treatments. Moreover, we found that pH was the key factor associated with the changes in the abundance and structure of the bacterial community. Cover crop treatments altered the bacterial community structure with shifts in the dominant genera, which have plant-growth-promoting and/or pathogen-antagonistic potentials, e.g., increased the abundances of Streptomyces, Arthrobacter, and Bacillus spp. in the W and WRB, and Gaiella spp. in the WB. Overall, we found that cover crops altered the soil physicochemical properties and bacterial community, and these changes varied with species composition of the cover crops, with wheat and its combination with legumes as most effective treatments. These results suggest that the diversification within cover crops could provide better crop yield stimulatory affects by altering soil biochemical environment.

2020 ◽  
Vol 8 (6) ◽  
pp. 834
Author(s):  
Naihui Li ◽  
Danmei Gao ◽  
Xingang Zhou ◽  
Shaocan Chen ◽  
Chunxia Li ◽  
...  

Intercropping can achieve sustainable agricultural development by increasing plant diversity. In this study, we investigated the effects of tomato monoculture and tomato/potato-onion intercropping systems on tomato seedling growth and changes of soil microbial communities in greenhouse conditions. Results showed that the intercropping with potato-onion increased tomato seedling biomass. Compared with monoculture system, the alpha diversity of soil bacterial and fungal communities, beta diversity and abundance of bacterial community were increased in the intercropping system. Nevertheless, the beta-diversity and abundance of fungal community had no difference between the intercropping and monoculture systems. The relative abundances of some taxa (i.e., Acidobacteria-Subgroup-6, Arthrobacter, Bacillus, Pseudomonas) and several OTUs with the potential to promote plant growth were increased, while the relative abundances of some potential plant pathogens (i.e., Cladosporium) were decreased in the intercropping system. Redundancy analysis indicated that bacterial community structure was significantly influenced by soil organic carbon and pH, the fungal community structure was related to changes in soil organic carbon and available phosphorus. Overall, our results suggested that the tomato/potato-onion intercropping system altered soil microbial communities and improved the soil environment, which may be the main factor in promoting tomato growth.


Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 190
Author(s):  
Sangsub Cha ◽  
Yong Suk Kim ◽  
Ah Lim Lee ◽  
Dong-Hyeon Lee ◽  
Namin Koo

Soil acidification caused by anthropogenic activities adversely affects forest ecosystems by altering soil pH, which is an important factor in soil quality and function. Liming is one suggested way to solve this problem. This study was performed to evaluate the effects of liming in acidic forest soils by determining soil microbial biomass, microbial community structure, and extracellular enzyme activities associated with carbon, nitrogen, and phosphorus cycling. Lime treatment increased soil pH by up to 40%, significantly increased organic matter (OM) content at some sites, and altered the enzyme activity of the soil. With liming, the microbial biomass appeared to be affected by the chemical properties of the soil, such as pH, Ca2+, Mg2+, K+, and exchangeable aluminum (Ale) levels, although there were no significant differences at the site level. Enzymatic activity was found to be affected by pH, Ca2+, Mg2+, electrical conductivity (EC), and Ale; and acid phosphatase (AP) and phenol oxidase (POX) activity were significantly affected by lime treatment. AP activity decreased from 0.62 to 0.66, and POX activity increased from 1.75 to 3.00 in part of the sites. The bacterial community richness was influenced by pH as a direct effect of lime treatment. The fungal community richness was associated with changes in K+ that were not due to lime treatment. The bacterial community structure was affected by soil OM, total nitrogen (TN), pH, and Ca2+; and the fungal community structure was affected by pH, Mg2+, and K+. In conclusion, changes in soil environmental conditions by liming can affect soil microbial communities and functions through direct or indirect processes, further changing ecosystem processes.


2021 ◽  
Author(s):  
Micaela Tosi ◽  
John Drummelsmith ◽  
Dasiel Obregón ◽  
Inderjot Chahal ◽  
Laura L. Van Eerd ◽  
...  

Abstract Sustainable agricultural practices such as crop diversification, cover crops and residue retention are increasingly applied to counteract detrimental effects of agriculture on natural resources. Since part of their effects occur via changes soil microbial communities, it is critical to understand how these respond to different practices. Our study analyzed five cover crop (cc) treatments (oat, rye, radish, rye-radish mixture and no-cc control) and two crop residue management strategies (retention/R+ or removal/R-) in an 8-year diverse horticultural crop rotation trial from ON, Canada. Cc effects were small but stronger than those of residue management. Radish-based cover crops tended to be the most beneficial for both microbial abundance and richness, yet detrimental for fungal evenness. Cc species, in particular radish, also shaped fungal and, to a lesser extent, prokaryotic community composition. Crop residues modulated cc effects on bacterial abundance and fungal evenness (i.e., more sensitive in R- than R+), as well as microbial taxa. Several microbial structure features, some affected by cc, were correlated with early tomato growth in the following spring (e.g., composition, taxa within Actinobacteria, Firmicutes and Ascomycota). Our study suggests that, whereas mid-term cc effects were small, they need to be better understood as they could be influencing crop productivity via plant-soil feedbacks.


2006 ◽  
Vol 72 (12) ◽  
pp. 7804-7812 ◽  
Author(s):  
Martin Hartmann ◽  
Franco Widmer

ABSTRACT Changes in the diversity and structure of soil microbial communities may offer a key to understanding the impact of environmental factors on soil quality in agriculturally managed systems. Twenty-five years of biodynamic, bio-organic, or conventional management in the DOK long-term experiment in Switzerland significantly altered soil bacterial community structures, as assessed by terminal restriction fragment length polymorphism (T-RFLP) analysis. To evaluate these results, the relation between bacterial diversity and bacterial community structures and their discrimination potential were investigated by sequence and T-RFLP analyses of 1,904 bacterial 16S rRNA gene clones derived from the DOK soils. Standard anonymous diversity indices such as Shannon, Chao1, and ACE or rarefaction analysis did not allow detection of management-dependent influences on the soil bacterial community. Bacterial community structures determined by sequence and T-RFLP analyses of the three gene libraries substantiated changes previously observed by soil bacterial community level T-RFLP profiling. This supported the value of high-throughput monitoring tools such as T-RFLP analysis for assessment of differences in soil microbial communities. The gene library approach also allowed identification of potential management-specific indicator taxa, which were derived from nine different bacterial phyla. These results clearly demonstrate the advantages of community structure analyses over those based on anonymous diversity indices when analyzing complex soil microbial communities.


2020 ◽  
Author(s):  
Jingjie Hao ◽  
Yen Ning Chai ◽  
Raziel A. Ordóñez ◽  
Emily E. Wright ◽  
Sotirios Archontoulis ◽  
...  

AbstractThe determination of how microbial community structure changes within the soil profile, will be beneficial to understanding the long-term health of agricultural soil ecosystems and will provide a first step towards elucidating how deep soil microbial communities contribute to carbon sequestration. This study aimed to investigate the differences in the microbial community abundance, composition and diversity throughout from the surface layers down to deep soils in corn and soybean fields in Iowa, USA. We used 16S rRNA amplicon sequencing of soil samples to characterize the change in microbial community structure. Our results revealed decreased richness and diversity in bacterial community structure with increasing soil depth. We also observed distinct distribution patterns of bacterial community composition along soil profiles. Soil and root data at different depths enabled us to demonstrate that the soil organic matter, soil bulk density and plant water availability were all significant factors in explaining the variation in soil microbial community composition. Our findings provide valuable insights in the changes in microbial community structure to depths of 180 cm in one of the most productive agricultural regions in the world. This knowledge will be important for future management and productivity of agroecosystems in the face of increasing demand for food and climate change.


2019 ◽  
Author(s):  
Sreejata Bandopadhyay ◽  
Henry Y. Sintim ◽  
Jennifer M. DeBruyn

AbstractPolyethylene (PE) plastic mulch films are used globally in crop production but incur considerable disposal and environmental pollution issues. Biodegradable plastic mulch films (BDMs), an alternative to PE-based films, are designed to be tilled into the soil where they are expected to be mineralized to carbon dioxide, water and microbial biomass. However inadequate research regarding the impacts of repeated incorporation of BDMs on soil microbial communities has partly contributed to limited adoption of BDMs. In this study, we evaluated the effects of BDM incorporation on soil microbial community structure and function over two years in two geographical locations: Knoxville, TN, and in Mount Vernon, WA. Treatments included four plastic BDMs, a completely biodegradable cellulose mulch, a non-biodegradable PE mulch and a no mulch plot. Bacterial community structure determined using 16S rRNA amplicon sequencing revealed significant differences by location and season. Differences in bacterial communities by mulch treatment were not significant for any season in either location, except for Fall 2015 in WA where differences were observed between BDMs and no-mulch plots. Extracellular enzyme rate assays were used to characterize communities functionally, revealing significant differences by location and sampling season in both TN and WA but minimal differences between BDMs and PE treatments. Limited effects of BDM incorporation on soil bacterial community structure and soil enzyme activities when compared to PE suggest that BDMs have comparable influences on soil microbial communities, and therefore could be considered an alternative to PE.ImportancePlastic film mulches increase crop yields and improve fruit quality. Most plastic mulches are made of polyethylene (PE), which is poorly degradable, resulting in undesirable end-of-life outcomes. Biodegradable mulches (BDMs) may be a sustainable alternative to PE. BDMs are made of polymers which can be degraded by soil microbial enzymes, and are meant to be tilled into soil after use. However, uncertainty about impacts of tilled-in BDMs on soil health has restricted adoption of BDMs. Our previous research showed BDMs did not have a major effect on a wide range of soil quality indicators (Sintim et al. 2019); here we focus on soil microbial communities, showing that BDMs do not have detectable effects on soil microbial communities and their functions, at least over the short term. This informs growers and regulators about use of BDMs in crop production, paving a way for an agricultural practice that reduces environmental plastic pollution.


Agriculture ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Babacar Thioye ◽  
Marc Legras ◽  
Lisa Castel ◽  
François Hirissou ◽  
Naouel Chaftar ◽  
...  

Soil microorganisms play a central role in biological soil functioning. One of the beneficial microbiota that has a symbiotic association with most of the plants is arbuscular mycorrhizal fungi (AMF). Nevertheless, little is known about the impact of cover crops—widely used in conservation agriculture or organic farming—on native mycorrhizal fungi. This study was conducted in Southern France, in 20-year-old walnut orchards, where faba bean (Vicia faba Roth) was intercropped. To find whether the native AM fungal community associated with walnut trees was influenced by cover crops and soil microbial communities, analyses of soil physicochemical and microbiological indicators were carried out with roots and soil samples collected from four modalities (walnut in conventional farming with and without cover crops, and walnut in organic farming with and without cover crops). Our results showed that the presence of cover crops mainly influenced the soil microbial abundance and activities in conventional plots. In contrast, cover crops stimulated AM fungal colonization of walnut roots in organic plots, reaching 35% and 54% for arbuscule abundance and mycorrhizal intensity, respectively. In conventional plots, ergosterol and mineral nitrogen contents were mainly correlated with mycorrhizal colonization, while only acid phosphatase activity in soil was positively correlated with mycorrhizal colonization in organic plots. The use of the faba bean showed the great role played by cover crops in the enhancement of walnut trees’ mycorrhizal colonization. Identification of the functional traits of AM fungi sensitive to walnut trees is required to inform decisions in specific agricultural practices.


2022 ◽  
Author(s):  
Yiyun Liu ◽  
Yingming Xu ◽  
Qingqing Huang ◽  
Xu Qin ◽  
Lijie Zhao ◽  
...  

Abstract The objective of this study was to expound possible effect of fertilization and water management in the remediation process of hazardous substance using sepiolite(SP). Meanwhile, Illumina high-throughput sequencing was performed to investigate how the composition of the rhizosphere bacterial community responded to a series of soil remediation process. The results showed that application of SP increased pH, decreased DOM under different water condition, but goat manure (GM) increased pH and DOM at the same time. Under water-saturated condition (FWHC), the application of GM increased the content of available Cd (DTPA-Cd) by 42.0-68.9%, 13.1%-30.3% of unamended and SP-amended soil, respectively. Under normal water condition (NWHC), the application of GM increased DTPA-Cd by 0.7%-5.8%, 73.7%-115.5% of unamended and SP-amended soil, respectively. Consequently, coupling effect of FWHC and GM decreased Cd content in shoots of pak choi. We also found that the application of GM increased the abundance of soil microbial communities. Abundance of proteobacteria reached a peak when applied GM in SP-amended soil under FWHC. RDA analysis showed that soil microbes such as bacteroidetes, patescibacteria, and proteobacteria were correlated positively with pH, DOM, and DTPA-Cd. Acidobacteria was correlated positively with DTPA-Cd, and negatively with pH and DOM. The relationship of soil physicochemical properties and the bacterial community variation indicated that GM and SP mixed additives may indirectly affect the soil microbial community by changing soil physicochemical properties and available Cd content.


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