RESUMO
Sustainable management of the Amazon rainforest is fundamental for supporting life on earth because of its crucial role in sequestering carbon. One of the species grown in the forest is açaí (Euterpe oleracea), which is an important food and income source for its inhabitant. The acai seed, resulting from the processing of the fruit, is a solid organic residue, which has been an agent of undesirable environmental impacts such as natural landscape modifications, clogging sewers and water courses, eutrophication of surface waters. In this research, we evaluated the use of wood chips as a source of energy in a rustic oven to produce acai biochar so that family farmers carry out sustainable management of the residue and use biochar to improve soil quality and produce seedlings of native plants to regenerate degraded forests. The experiment was conducted in Pará, Brazil, Amazon region, using a randomized complete block design. A factorial treatment structure was implemented consisting of four biochar particle sizes (3, 5, 7, and 12 mm), 4 application rates (4, 8, 16, and 32 t ha-1), and a biochar-free control, with 5 replications. The results showed that the methodology for biochar production was easy to apply and low cost, allowing its use by family farmers. The combination of biochar rate and particle size affected soil properties and the development of black pepper seedlings in different ways. The soil properties affected were water retention capacity, moisture, fluorescein diacetate hydrolysis and arylsulphatase activity. The growth parameters of the affected black pepper seedlings were height and root system development.
Assuntos
Carvão Vegetal , Plântula , Sementes , Solo , Solo/química , Plântula/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Brasil , Piper nigrumRESUMO
Land degradation by deforestation adversely impacts soil properties, and long-term restoration practices have been reported to potentially reverse these effects, particularly on soil microorganisms. However, there is limited knowledge regarding the short-term effects of restoration on the soil bacterial community in semiarid areas. This study evaluates the bacterial community in soils experiencing degradation (due to slash-and-burn deforestation) and restoration (utilizing stone cordons and revegetation), in comparison to a native soil in the Brazilian semiarid region. Three areas were selected: (a) under degradation; (b) undergoing short-term restoration; and (c) a native area, and the bacterial community was assessed using 16S rRNA sequencing on soil samples collected during both dry and rainy seasons. The dry and rainy seasons exhibited distinct bacterial patterns, and native sites differed from degraded and restoration sites. Chloroflexi and Proteobacteria phyla exhibited higher prevalence in degraded and restoration sites, respectively, while Acidobacteria and Actinobacteria were more abundant in sites undergoing restoration compared to degraded sites. Microbial connections varied across sites and seasons, with an increase in nodes observed in the native site during the dry season, more edges and positive connections in the restoration site, and a higher occurrence of negative connections in the degradation site during the rainy season. Niche occupancy analysis revealed that degradation favored specialists over generalists, whereas restoration exhibited a higher prevalence of generalists compared to native sites. Specifically, degraded sites showed a higher abundance of specialists in contrast to restoration sites. This study reveals that land degradation impacts the soil bacterial community, leading to differences between native and degraded sites. Restoring the soil over a short period alters the status of the bacterial community in degraded soil, fostering an increase in generalist microbes that contribute to enhanced soil stability.
Assuntos
Bactérias , Solo , RNA Ribossômico 16S/genética , Brasil , Bactérias/genética , Acidobacteria/genética , Microbiologia do SoloRESUMO
Land desertification poses a significant challenge in the Brazilian semiarid region, encompassing a substantial portion of the country. Within this region, the detrimental effects of human activities, particularly unsuitable anthropic actions, have resulted in diminished vegetation cover and an accelerated rate of soil erosion. Notably, practices such as overgrazing and the conversion of native forests into pasturelands have played a pivotal role in exacerbating the process of land desertification. Ultimately, land desertification results in significant losses of soil organic matter and microbial diversity. To address this pressing issue and contribute to the existing literature, various land restoration practices, such as grazing exclusion, cover crops, and terracing, have been implemented in the Brazilian semiarid. These practices have shown promising results in terms of enhancing soil fertility and restoring microbial properties. Nonetheless, their effectiveness in improving soil microbial properties in the Brazilian semiarid region remains a subject of ongoing study. Recent advances in molecular techniques have improved our understanding of microbial communities in lands undergoing desertification and restoration. In this review, we focus on assessing the effectiveness of these restoration practices in revitalizing soil microbial properties, with a particular emphasis on the soil microbiome and its functions. Through a critical assessment of the impact of these practices on soil microbial properties, our research aims to provide valuable insights that can help mitigate the adverse effects of desertification and promote sustainable development in this ecologically sensitive region.
Assuntos
Conservação dos Recursos Naturais , Solo , Humanos , Microbiologia do Solo , Brasil , Florestas , ChinaRESUMO
Silicon (Si) fertilization is widely recognized to improve the development of crops, especially in tropical soils and cultivation under dryland management. Herein, our working hypothesis was that Si stoichiometry favors the efficient use of carbon (C), nitrogen (N), and phosphorus (P) in sugarcane plants. Therefore, a field experiment was carried out using a 3 × 3 factorial scheme consisting of three cultivars (RB92579, RB021754 and RB036066) and three forms of Si application (control without Si; sodium silicate spray at 40 mmol L-1 in soil during planting; sodium silicate spray at 40 mmol L-1 on leaves at 75 days after emergence). All Si fertilizations altered the elemental C and P stoichiometry and sugarcane yield, but silicon-induced responses varied depending on sugarcane cultivar and application method. The most prominent impacts were found in the leaf Si-sprayed RB92579 cultivar, with a significant increase of 7.0% (11 Mg ha-1) in stalk yield, 9.0% (12 Mg ha-1) in total recoverable sugar, and 20% (4 Mg ha-1) in sugar yield compared to the Si-without control. In conclusion, our findings clearly show that silicon soil and foliar fertilization alter C:N:P stoichiometry by enhancing the efficiency of carbon and phosphorus utilization, leading to improved sugarcane production and industrial quality.
Assuntos
Saccharum , Silício , Grão Comestível , Carbono , Carboidratos da Dieta , Fósforo , Solo , FertilizaçãoRESUMO
Soybean-maize are cultivated in different management systems, such as no-tillage and pastures, which presents potential to add organic residues, and it can potentially impacts the soil microbial community present in these systems. Thus, this study aimed to examine the effects of different soybean-maize management practices on the diversity and composition of soil microbial communities. Specifically, 16 S rRNA amplicon sequencing was used to investigate whether the use of pasture species in a fallowing system influences microbial communities in a soybean-maize rotation system, as compared to conventional tillage and no-tillage systems. The results indicate that the inclusion of the pasture species Urochloa brizantha in soybean-maize management systems leads to distinct responses within the soil microbial community. It was found that different soybean-maize management systems, particularly those with U. brizantha, affected the microbial community, likely due to the management applied to this pasture species. The system with 3 years of fallowing before soybean-maize showed the lowest microbial richness (â¼2000 operational taxonomic units) and diversity index (â¼6.0). Proteobacteria (â¼30%), Acidobacteria (â¼15%), and Verrucomicrobia (â¼10%) were found to be the most abundant phyla in the soil under tropical native vegetation, while soils under cropland had an increased abundance of Firmicutes (â¼30% to â¼50%) and Actinobacteria (â¼30% to â¼35%). To summarize, this study identified the impacts of various soybean-maize management practices on the soil microbial community and emphasized the advantages of adding U. brizantha as a fallow species.
Assuntos
Microbiota , Solo , Solo/química , Zea mays/microbiologia , Glycine max , Microbiologia do SoloRESUMO
Soils from Brazilian semiarid regions are highly vulnerable to desertification due to their geology, climate, human actions, and intensive land use that contribute to desertification. Therefore, areas under desertification have increased in the Brazilian semiarid region and it has negatively changed the soil bacterial and archaeal communities and their functionality. On the other hand, although restoration strategies are expensive and there are few soils restoration programs, some practices have been applied to restore these soils under desertification. For instance, conservationist practices and grazing exclusion have been strategically implemented, and they created a new altered soil condition for soil microbial communities, boosting soil microbial diversity. Here, we discuss the potential of these restoration strategies to recover the richness and diversity of soil bacterial and archaeal communities that were described through environmental DNA (eDNA) sequencing of soil samples. eDNA sequencing results show that areas where restoration strategies have been applied in regions under desertification in the Brazilian semiarid have increased species richness, diversity, and structure of the bacterial and archaeal community. In addition, network connectivity and functionality of the soil microorganisms have been improved over time. Altogether, we show that management strategies for soil restoration have positive effects on soil microbial communities and these effects can be monitored using the eDNA sequencing approach.
Assuntos
Archaea , DNA Ambiental , Humanos , Archaea/genética , Solo/química , Conservação dos Recursos Naturais , Brasil , Microbiologia do Solo , Bactérias/genética , RNA Ribossômico 16S/genéticaRESUMO
Plants modulate the soil microbiota and select a specific microbial community in the rhizosphere. However, plant domestication reduces genetic diversity, changes plant physiology, and could have an impact on the associated microbiome assembly. Here, we used 16S rRNA gene sequencing to assess the microbial community in the bulk soil and rhizosphere of wild, semi-domesticated, and domesticated genotypes of lima bean (Phaseolus lunatus), to investigate the effect of plant domestication on microbial community assembly. In general, rhizosphere communities were more diverse than bulk soil, but no differences were found among genotypes. Our results showed that the microbial community's structure was different from wild and semi-domesticated as compared to domesticated genotypes. The community similarity decreased 57.67% from wild to domesticated genotypes. In general, the most abundant phyla were Actinobacteria (21.9%), Proteobacteria (20.7%), Acidobacteria (14%), and Firmicutes (9.7%). Comparing the different genotypes, the analysis showed that Firmicutes (Bacillus) was abundant in the rhizosphere of the wild genotypes, while Acidobacteria dominated semi-domesticated plants, and Proteobacteria (including rhizobia) was enriched in domesticated P. lunatus rhizosphere. The domestication process also affected the microbial community network, in which the complexity of connections decreased from wild to domesticated genotypes in the rhizosphere. Together, our work showed that the domestication of P. lunatus shaped rhizosphere microbial communities from taxonomic to a functional level, changing the abundance of specific microbial groups and decreasing the complexity of interactions among them.
Assuntos
Microbiota , Phaseolus , Phaseolus/genética , Phaseolus/microbiologia , Raízes de Plantas/microbiologia , Rizosfera , Domesticação , RNA Ribossômico 16S/genética , Microbiota/genética , Proteobactérias/genética , Plantas , Acidobacteria/genética , Solo/química , Microbiologia do SoloRESUMO
Soil enzymes play a fundamental role in nutrient cycling in forest systems. The stoichiometry of C, N, and Pacquiring enzymes has been used to indicate nutrient limitation in the soil. However, the enzymatic stoichiometry remains poorly understood in pure and mixed eucalypt plantations. Thus, this study aims to assess the activity of enzymes in the soil to address the hypothesis that the introduction of N2-fixing trees could influence the enzymatic stoichiometry on C, N, and P cycling. The activity of ß-glucosidase (BG), urease (U), and acid phosphatase (AP) was assessed in soil (0-20 cm depth) of pure Eucalyptus grandis without (E) and with N fertilization (E+N), and a mixed system with E. grandis and Acacia mangium (E+A), and a pure A. mangium (A) plantation at 27 and 39 months after planting. The activities of BG/U, BG/AP, and U/AP were used to calculate the enzyme C/N, C/P, and N/P ratios, respectively. Rates of Nacquiring enzymes were higher in E and E+N, while soil microorganisms invested in Pacquiring enzymes in A and E+A. The vector length and angle demonstrated that C demand by microorganisms does not change in relation to N and P, regardless of the treatment. However, N demand decreased in relation to P in A and E+A (mainly at 27 months). Our results suggest that enzymes activity in pure eucalypt systems is limited for their soil-litter nutrient contents. At the same time while acacia and mixed plantation seem to invest in Pacquiring enzymes to improve biological N2 fixation promoted by diazotrophic bacteria associated to acacia.
Assuntos
Microbiologia do Solo , Ativadores de Enzimas/análise , Eucalyptus , Fixação de NitrogênioRESUMO
Bacteria have potential to tolerate and reduce metals. This study evaluated the potential of selected bacterial strains in tolerating and reducing chromium (Cr). Six bacterial strains (Rhizobium miluonense LCC01, LCC04, LCC05, and LCC69; Rhizobium pusense LCC43; and Agrobacterium deltaense LCC50) showed tolerance to Cr(VI) (16 and 32 µg mL-1), reduction potential of Cr(VI) (from 50 to 80%), and efficiency in producing exopolysaccharides. Rhizobium pusense LCC43 exhibited the highest tolerance (128 µg mL-1), reduction potential of Cr(VI) (from 80 to 100%), and efficiency in producing exopolysaccharides. These results suggested that this strain may have the potential to be used in the bioremediation of soils contaminated with Cr(VI).
Assuntos
Bactérias , Cromo , Oxirredução , Bactérias/genéticaRESUMO
The tannery industries generate a solid waste known as tannery sludge, which is composed of organic and inorganic compounds, mainly chromium (Cr). When Cr is not removed from the tannery sludge, this solid waste is metal-rich and its application could affect the soil microorganisms. Alternatively, the composting of the tannery sludge can contribute to decreasing the concentration of Cr in the composted tannery sludge (CTS). However, in some cases, the concentration of Cr remains high in the CTS. During the last 10 years, the Cr-rich CTS has been successively applied in the soil, and its effect on soil microbial properties was verified. Here, we discuss the effect of successive applications of Cr-rich CTS on soil microbes. Interestingly, the findings have shown that successive applications of Cr-rich CTS selected specific soil microbial groups with potential functions. In addition, the studies added a new focus to further research evaluating the potential effect of successive applications of Cr-rich CTS on the rare microbial community.