Pub Date : 2022-08-29DOI: 10.3389/fsoil.2022.927452
M. Graham, K. Butterbach‐Bahl, C. J. L. du Doit, D. Korir, S. Leitner, L. Merbold, A. Mwape, P. Ndung'u, D. Pelster, M. Rufino, T. J. van der Weerden, A. Wilkes, C. Arndt
Livestock are an important source of livelihoods in agricultural systems in sub-Saharan Africa (SSA), while also being the largest source of national greenhouse gas (GHG) emissions in most African countries. As a consequence, there is a critical need for data on livestock GHG sources and sinks to develop national inventories, as well as conduct baseline measurements and intervention testing to mitigate GHG emissions and meet ambitious national climate goals. Our objective was to review studies on GHG emissions from livestock systems in SSA, as well as soil carbon storage in livestock-dominated systems (i.e., grasslands and rangelands), to evaluate best current data and suggest future research priorities. To this end, we compiled studies from SSA that determined emission factors (EFs) for enteric methane and manure emissions, along with studies on soil organic carbon (SOC) stocks in SSA. We found that there has been limited research on livestock GHG emissions and SOC relative to national ambitions for climate change mitigation in SSA. Enteric methane emission factors (EFs) in low productivity cattle systems may be lower than IPCC Tier 1 default EFs, whereas small ruminants (i.e. sheep and goats) had higher EFs compared to IPCC Tier 1 EFs. Manure EFs were equal to or lower than IPCC Tier 1 EFs for deposited manure (while grazing), manure applied as fertilizer, and manure management. SOC stocks for grasslands and rangelands in SSA show broad agreement with IPCC estimates, but there was a strong geographic bias and many studies did not report soil type, bulk density, or SOC stocks at >30 cm depth. In general, the largest data gaps included information for manure (quantity, quality, management), small ruminants, agropastoral/pastoralist systems, and in general from West Africa. Future research should focus on filling major data gaps on locally appropriate mitigation interventions and improving livestock activity data for developing Tier 2 GHG inventories in SSA. At the science-policy interface, all parties would benefit from enhanced coordination within the research community and between researchers and African governments to improve Tier 2 inventories and harmonize measurement for mitigation in livestock systems in SSA.
{"title":"Research Progress on Greenhouse Gas Emissions From Livestock in Sub-Saharan Africa Falls Short of National Inventory Ambitions","authors":"M. Graham, K. Butterbach‐Bahl, C. J. L. du Doit, D. Korir, S. Leitner, L. Merbold, A. Mwape, P. Ndung'u, D. Pelster, M. Rufino, T. J. van der Weerden, A. Wilkes, C. Arndt","doi":"10.3389/fsoil.2022.927452","DOIUrl":"https://doi.org/10.3389/fsoil.2022.927452","url":null,"abstract":"Livestock are an important source of livelihoods in agricultural systems in sub-Saharan Africa (SSA), while also being the largest source of national greenhouse gas (GHG) emissions in most African countries. As a consequence, there is a critical need for data on livestock GHG sources and sinks to develop national inventories, as well as conduct baseline measurements and intervention testing to mitigate GHG emissions and meet ambitious national climate goals. Our objective was to review studies on GHG emissions from livestock systems in SSA, as well as soil carbon storage in livestock-dominated systems (i.e., grasslands and rangelands), to evaluate best current data and suggest future research priorities. To this end, we compiled studies from SSA that determined emission factors (EFs) for enteric methane and manure emissions, along with studies on soil organic carbon (SOC) stocks in SSA. We found that there has been limited research on livestock GHG emissions and SOC relative to national ambitions for climate change mitigation in SSA. Enteric methane emission factors (EFs) in low productivity cattle systems may be lower than IPCC Tier 1 default EFs, whereas small ruminants (i.e. sheep and goats) had higher EFs compared to IPCC Tier 1 EFs. Manure EFs were equal to or lower than IPCC Tier 1 EFs for deposited manure (while grazing), manure applied as fertilizer, and manure management. SOC stocks for grasslands and rangelands in SSA show broad agreement with IPCC estimates, but there was a strong geographic bias and many studies did not report soil type, bulk density, or SOC stocks at >30 cm depth. In general, the largest data gaps included information for manure (quantity, quality, management), small ruminants, agropastoral/pastoralist systems, and in general from West Africa. Future research should focus on filling major data gaps on locally appropriate mitigation interventions and improving livestock activity data for developing Tier 2 GHG inventories in SSA. At the science-policy interface, all parties would benefit from enhanced coordination within the research community and between researchers and African governments to improve Tier 2 inventories and harmonize measurement for mitigation in livestock systems in SSA.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44552373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-15DOI: 10.3389/fsoil.2022.877261
M. He, Liang Tang, Cheng-yi Li, Jianxin Ren
Soil organic carbon is an important factor for the cultivation and production of traditional Chinese medicine. This study aimed to reveal the spatial distribution of the soil organic carbon density (SOCD) and the effects of the climatic and topographic factors in Longxi County (Gansu Province, China). The soil organic carbon (SOC) from 200 sampling points were collected and analyzed in 2018. Results showed that the total SOCD was 26.7 ± 10.2 Mg ha-1, while the SOCDs at a soil depth of 0–10, 10–30, and 30–50 cm were 6.3 ± 1.7, 11.0 ± 3.8, and 9.3 ± 4.8 Mg ha-1, respectively. The temperature, precipitation, elevation, and stream power index showed significant correlations with the SOCD at each soil layer. With an increasing soil depth, the correlation between the slope, relief amplitude, surface roughness, and SOCD gradually decreased. From the central plains to the mountainous areas, the SOCD increased with rising elevation, while the valley plain that formed by the river basin showed low levels of SOCD. Therefore, the scientific management of soil fertility and the development of precision agriculture, combined in a soil testing fertilization formula, will guarantee the healthy development of the Chinese herbal medicine planting.
{"title":"Factors controlling the spatial distribution of soil organic carbon in the Chinese medicine producing area of NW China 1","authors":"M. He, Liang Tang, Cheng-yi Li, Jianxin Ren","doi":"10.3389/fsoil.2022.877261","DOIUrl":"https://doi.org/10.3389/fsoil.2022.877261","url":null,"abstract":"Soil organic carbon is an important factor for the cultivation and production of traditional Chinese medicine. This study aimed to reveal the spatial distribution of the soil organic carbon density (SOCD) and the effects of the climatic and topographic factors in Longxi County (Gansu Province, China). The soil organic carbon (SOC) from 200 sampling points were collected and analyzed in 2018. Results showed that the total SOCD was 26.7 ± 10.2 Mg ha-1, while the SOCDs at a soil depth of 0–10, 10–30, and 30–50 cm were 6.3 ± 1.7, 11.0 ± 3.8, and 9.3 ± 4.8 Mg ha-1, respectively. The temperature, precipitation, elevation, and stream power index showed significant correlations with the SOCD at each soil layer. With an increasing soil depth, the correlation between the slope, relief amplitude, surface roughness, and SOCD gradually decreased. From the central plains to the mountainous areas, the SOCD increased with rising elevation, while the valley plain that formed by the river basin showed low levels of SOCD. Therefore, the scientific management of soil fertility and the development of precision agriculture, combined in a soil testing fertilization formula, will guarantee the healthy development of the Chinese herbal medicine planting.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45450181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-12DOI: 10.3389/fsoil.2022.959325
Ismail Koné, Konan-Kan Hippolyte Kouadio, Emmanuel N’Goran Kouadio, W. Agyare, N. Owusu-Prempeh, William Amponsah, T. Gaiser
Cotton is the main cash crop in northern Côte d’Ivoire, where intensive cultivation along with low external inputs has led to a decline in crop yields due to soil degradation. The present study aims to assess the evolution of soil fertility during the 2013 and 2021 periods in the cotton basin area of Côte d’Ivoire. More specifically, the study (i) identified the limiting physico-chemical parameters of soil fertility, and (ii) analysed the state of evolution of soil fertility in 2013 and 2021 in the cotton basin of Côte d’Ivoire. For this purpose, a total of 64 soil samples were taken in 2013 and in 2021 on the same cotton plots on the 0-20 cm horizon. Chemical analyses of the soil samples in the laboratory were carried out on the following parameters: particle size distribution, pH water, total nitrogen (NT), Potassium (K+), Calcium (Ca2+), Magnesium (Mg2+), Sodium (Na+) and Cation exchange capacity (CEC). The results of the soil analyses showed that the sandy-clay textured topsoils dominate the whole study area in both years. This leads to a low retention capacity of exchangeable bases. Determination of the soil pH showed that the pH varies from slightly acidic to neutral (6.5
{"title":"Assessment of soil fertility status in cotton-based cropping systems in Cote d’Ivoire","authors":"Ismail Koné, Konan-Kan Hippolyte Kouadio, Emmanuel N’Goran Kouadio, W. Agyare, N. Owusu-Prempeh, William Amponsah, T. Gaiser","doi":"10.3389/fsoil.2022.959325","DOIUrl":"https://doi.org/10.3389/fsoil.2022.959325","url":null,"abstract":"Cotton is the main cash crop in northern Côte d’Ivoire, where intensive cultivation along with low external inputs has led to a decline in crop yields due to soil degradation. The present study aims to assess the evolution of soil fertility during the 2013 and 2021 periods in the cotton basin area of Côte d’Ivoire. More specifically, the study (i) identified the limiting physico-chemical parameters of soil fertility, and (ii) analysed the state of evolution of soil fertility in 2013 and 2021 in the cotton basin of Côte d’Ivoire. For this purpose, a total of 64 soil samples were taken in 2013 and in 2021 on the same cotton plots on the 0-20 cm horizon. Chemical analyses of the soil samples in the laboratory were carried out on the following parameters: particle size distribution, pH water, total nitrogen (NT), Potassium (K+), Calcium (Ca2+), Magnesium (Mg2+), Sodium (Na+) and Cation exchange capacity (CEC). The results of the soil analyses showed that the sandy-clay textured topsoils dominate the whole study area in both years. This leads to a low retention capacity of exchangeable bases. Determination of the soil pH showed that the pH varies from slightly acidic to neutral (6.5<pH<7). The most limiting chemical properties are Cation exchange capacity (CEC) and the sum of the exchangeable bases (SEB) in the department of Korogho, Boundiali, and Ferkessedougou and the most limiting chemical properties in the department of Mankono are CEC. However, during the period from 2013 to 2021 the content of exchangeable cations (Ca2+, Mg2+ and K+) and the base saturation (BS) increased significantly in all the departments, more precisely in the department of Mankono. Although we observed a slight increase in the chemical properties of the soils in 2021 compared to 2013, the values were still below the minimum required threshold. This result implies that the soils have poor physico-chemical properties and consequently a low level of fertility, which compromises the sustainability of the cotton production system. The application of organic and mineral amendments is therefore essential to increase the nutrient content of these soils.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45901467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-10DOI: 10.3389/fsoil.2022.970380
S. R. Pinnamaneni, P. Mubvumba, S. Anapalli, K. N. Reddy
Planting winter cover crops (CC) in soybean cropping systems is expected to offer various environmental benefits including soil health and fertility besides enhanced cash crop productivity. In a three-year study (2018–2021) conducted on a Dundee silt loam, we assessed the impact of introducing rye (Secale cereale L.) CC during the winter fallow period on soil organic carbon (SOC), soil organic matter (SOM), soil total nitrogen (STN), bulk density (BD), saturated hydraulic conductivity (Kfs), soil penetration resistance (SPR), and water-stable aggregates (WSA). Three treatments evaluated were: i) no cover crop (NC), ii) winter rye as CC rolled when green and desiccated after soybean planting (GR), and iii) winter rye CC desiccated and rolled before planting soybean (BR) in a randomized complete block design with six replications. The depth of the soil sampling in 2019 was 0-15 and 15-30 cm while 0-10, 10-20 and 20-30 cm depth soil sampling was done in 2020 and 2021. Effects of BR and GR on soybean root growth characteristics (number of roots, root length and root angle) were measured using a CID 600 root scanner. The results showed that CC (both BR and GR) improved SOC by 7 to 12.5%, soil organic matter by 9 to 15%, STN by 13 to 29%, WSA by 26 to 68%, Kfs by 5 to 9% and reduced BD by 8% and SPR by 14 to 18% compared to NC (P<0.05). However, there were no differences between BR and GR treatments. Root characteristics of soybean in the NC, BR and GR treatments were similar. Rye CC fits into the existing soybean production system in the Lower Mississippi Delta with a potential to augment soil-physico chemical properties, thus offering agro-ecosystem services which may not necessarily lead to an impact on soybean root growth traits.
{"title":"Cereal rye (Secale cereale L.) cover crop improves soil physico-chemical properties with no influence on soybean (Glycine max L.) root growth parameters","authors":"S. R. Pinnamaneni, P. Mubvumba, S. Anapalli, K. N. Reddy","doi":"10.3389/fsoil.2022.970380","DOIUrl":"https://doi.org/10.3389/fsoil.2022.970380","url":null,"abstract":"Planting winter cover crops (CC) in soybean cropping systems is expected to offer various environmental benefits including soil health and fertility besides enhanced cash crop productivity. In a three-year study (2018–2021) conducted on a Dundee silt loam, we assessed the impact of introducing rye (Secale cereale L.) CC during the winter fallow period on soil organic carbon (SOC), soil organic matter (SOM), soil total nitrogen (STN), bulk density (BD), saturated hydraulic conductivity (Kfs), soil penetration resistance (SPR), and water-stable aggregates (WSA). Three treatments evaluated were: i) no cover crop (NC), ii) winter rye as CC rolled when green and desiccated after soybean planting (GR), and iii) winter rye CC desiccated and rolled before planting soybean (BR) in a randomized complete block design with six replications. The depth of the soil sampling in 2019 was 0-15 and 15-30 cm while 0-10, 10-20 and 20-30 cm depth soil sampling was done in 2020 and 2021. Effects of BR and GR on soybean root growth characteristics (number of roots, root length and root angle) were measured using a CID 600 root scanner. The results showed that CC (both BR and GR) improved SOC by 7 to 12.5%, soil organic matter by 9 to 15%, STN by 13 to 29%, WSA by 26 to 68%, Kfs by 5 to 9% and reduced BD by 8% and SPR by 14 to 18% compared to NC (P<0.05). However, there were no differences between BR and GR treatments. Root characteristics of soybean in the NC, BR and GR treatments were similar. Rye CC fits into the existing soybean production system in the Lower Mississippi Delta with a potential to augment soil-physico chemical properties, thus offering agro-ecosystem services which may not necessarily lead to an impact on soybean root growth traits.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47700248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-10DOI: 10.3389/fsoil.2022.905010
J. Okello, M. Bauters, H. Verbeeck, J. Kasenene, P. Boeckx
Tropical montane forests store large amounts of carbon (C), nitrogen (N), and phosphorus (P) in soil. These soil C, N, and P pools are vulnerable to increased losses due to the increasing local temperatures. To gain better insight into the effects of climate warming on biogeochemistry in montane forests in Africa, we established study plots along a natural climate gradient in Uganda between 1,250 and 3,000 m in the Rwenzori Mountains. We studied soil C, N, and P contents as well as 13C and 15N isotopic compositions and leaf nutrient contents. Further, we simulated climate warming by 0.9°C–2.8°C for 2 years by conducting in situ soil mesocosms translocation downslope. The results revealed that, along the elevational gradient, soil organic C increased six-fold from 2.6 ± 1.0% at 1,250–1,300 m to 16.0 ± 1.9% at 2,700–3,000 m, with a linear increase of 0.94% per 100 m of elevation increase. Similarly, soil total N increased five-fold, from 0.3 ± 0.1% to 1.3 ± 0.1%, with a linear increase of 0.07% per 100 m of elevation increase. Further, soil bio-available P increased three-fold, from 9.6 ± 5.2 mg kg−1 to 29.5 ± 3.0 mg kg−1, with a linear increase of 1.4 mg kg−1 per 100 m of elevation increase. Soil δ15N decreased linearly by 0.39‰ per 100 m of elevation increase, ranging from 8.9 ± 0.2‰ to 2.9 ± 0.7‰ at 1,250–1,300 m and 2,700–3,000 m, respectively. The accumulation of soil organic C and total N with elevation is due to slow microbial activity under lower temperature. Indeed, the soil δ15N indicated a more closed N cycling with increasing elevation. However, despite the increasing trend in soil C and nutrient status with elevation, leaf N and P contents decreased linearly with elevation. This is likely due to the impairment of nutrient uptake under low temperature and low pH. In addition, following 2 years of in situ soil warming, we found that the soil δ13C and δ15N values relatively increased. Generally, the results imply that warming triggered accelerated transformation processes of accrued soil organic matter.
{"title":"Response of Afromontane soil organic carbon, nitrogen, and phosphorus to in situ experimental warming along an elevational gradient","authors":"J. Okello, M. Bauters, H. Verbeeck, J. Kasenene, P. Boeckx","doi":"10.3389/fsoil.2022.905010","DOIUrl":"https://doi.org/10.3389/fsoil.2022.905010","url":null,"abstract":"Tropical montane forests store large amounts of carbon (C), nitrogen (N), and phosphorus (P) in soil. These soil C, N, and P pools are vulnerable to increased losses due to the increasing local temperatures. To gain better insight into the effects of climate warming on biogeochemistry in montane forests in Africa, we established study plots along a natural climate gradient in Uganda between 1,250 and 3,000 m in the Rwenzori Mountains. We studied soil C, N, and P contents as well as 13C and 15N isotopic compositions and leaf nutrient contents. Further, we simulated climate warming by 0.9°C–2.8°C for 2 years by conducting in situ soil mesocosms translocation downslope. The results revealed that, along the elevational gradient, soil organic C increased six-fold from 2.6 ± 1.0% at 1,250–1,300 m to 16.0 ± 1.9% at 2,700–3,000 m, with a linear increase of 0.94% per 100 m of elevation increase. Similarly, soil total N increased five-fold, from 0.3 ± 0.1% to 1.3 ± 0.1%, with a linear increase of 0.07% per 100 m of elevation increase. Further, soil bio-available P increased three-fold, from 9.6 ± 5.2 mg kg−1 to 29.5 ± 3.0 mg kg−1, with a linear increase of 1.4 mg kg−1 per 100 m of elevation increase. Soil δ15N decreased linearly by 0.39‰ per 100 m of elevation increase, ranging from 8.9 ± 0.2‰ to 2.9 ± 0.7‰ at 1,250–1,300 m and 2,700–3,000 m, respectively. The accumulation of soil organic C and total N with elevation is due to slow microbial activity under lower temperature. Indeed, the soil δ15N indicated a more closed N cycling with increasing elevation. However, despite the increasing trend in soil C and nutrient status with elevation, leaf N and P contents decreased linearly with elevation. This is likely due to the impairment of nutrient uptake under low temperature and low pH. In addition, following 2 years of in situ soil warming, we found that the soil δ13C and δ15N values relatively increased. Generally, the results imply that warming triggered accelerated transformation processes of accrued soil organic matter.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47381312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-04DOI: 10.3389/fsoil.2022.937186
E. Alori, Alhasan Idris Gabasawa, C. E. Elenwo, Oluwadolapo Ololade Agbeyegbe
Soils are polluted by both organic and inorganic substances. Plants growing in polluted soils suffer damages such as leaf rolls, chlorosis, growth inhibition, root tips browning, and death of plant. Soil pollutants such as hydrocarbon and heavy metals are absorbed by crops and such ends up being consumed by human posing health risk like cancer and respiratory abnormally. Conventional methods of remediation such as chemical and physical methods are very expensive and not sustainable. Excavation, which is a type of physical method, merely shifts the pollutant from one site to another. Bioremediation is a biological method of reclaiming polluted soils. Bioremediation is less expensive and more sustainable and safer when compared to the conventional methods of reclamation of polluted environment. This biological method of remediation is an extremely attractive, important, and productive alternative for cleaning, debugging, managing, and rehabilitating and consequently ameliorating contaminated environments via judicious utilization of microbial activities. The rate, at which the waste substances are degraded, is usually dictated by competitiveness among biological agents, sub-optimal supply of essential nutrients, unconducive abiotic conditions (in forms of temperature, aeration, pH, and moisture), and constrained pollutant’s bioavailability. Bioremediation is often effective only under conducive environmental conditions favorable for microbial growth and development. It has been successfully used at various parts of the world. Based on the significance of bioremediation in enhancing the reclamation of polluted environments by decontaminating and degrading heavy metals and xenobiotics, more focused researches would be needed so as to improve contaminated environments in much safer ways and conditions through bioremediation techniques. This research discussed the various types and methods of bioremediation. The mechanisms of actions and strategies of microorganisms in bioremediation were well expatiated. The interaction between bioremediators and the mineral particles in the soil environment was explained. Graphical Abstract
{"title":"Bioremediation techniques as affected by limiting factors in soil environment","authors":"E. Alori, Alhasan Idris Gabasawa, C. E. Elenwo, Oluwadolapo Ololade Agbeyegbe","doi":"10.3389/fsoil.2022.937186","DOIUrl":"https://doi.org/10.3389/fsoil.2022.937186","url":null,"abstract":"Soils are polluted by both organic and inorganic substances. Plants growing in polluted soils suffer damages such as leaf rolls, chlorosis, growth inhibition, root tips browning, and death of plant. Soil pollutants such as hydrocarbon and heavy metals are absorbed by crops and such ends up being consumed by human posing health risk like cancer and respiratory abnormally. Conventional methods of remediation such as chemical and physical methods are very expensive and not sustainable. Excavation, which is a type of physical method, merely shifts the pollutant from one site to another. Bioremediation is a biological method of reclaiming polluted soils. Bioremediation is less expensive and more sustainable and safer when compared to the conventional methods of reclamation of polluted environment. This biological method of remediation is an extremely attractive, important, and productive alternative for cleaning, debugging, managing, and rehabilitating and consequently ameliorating contaminated environments via judicious utilization of microbial activities. The rate, at which the waste substances are degraded, is usually dictated by competitiveness among biological agents, sub-optimal supply of essential nutrients, unconducive abiotic conditions (in forms of temperature, aeration, pH, and moisture), and constrained pollutant’s bioavailability. Bioremediation is often effective only under conducive environmental conditions favorable for microbial growth and development. It has been successfully used at various parts of the world. Based on the significance of bioremediation in enhancing the reclamation of polluted environments by decontaminating and degrading heavy metals and xenobiotics, more focused researches would be needed so as to improve contaminated environments in much safer ways and conditions through bioremediation techniques. This research discussed the various types and methods of bioremediation. The mechanisms of actions and strategies of microorganisms in bioremediation were well expatiated. The interaction between bioremediators and the mineral particles in the soil environment was explained. Graphical Abstract","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43020269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-04DOI: 10.3389/fsoil.2022.945888
T. Jeanne, Joël D’Astous-Pagé, R. Hogue
Several studies have shown that Illumina MiSeq high-throughput sequencing can be used to measure the diversity of prokaryotes and fungal communities that provide ecosystem functions in agricultural soils. Pedoclimatic properties of soils, together with cropping systems and agricultural management practices, are major drivers of soil microbiome diversity. Their effects must be quantified and compared to technical variability to improve the relevance of observed effects and the indicators that may result from them. This study was conducted: 1) To assess the effects of three sources of technical variability on the soil prokaryotes and fungal diversity; 2) To identify a source of technical variability that can be used as a threshold to better assess crop management effects; 3) To evaluate the effects of spatial and temporal variability compare to a technical threshold in three crop management contexts, potato, corn/soybean and grassland. Technical variability was evaluated in a basis of sampling, soil DNA extraction and amplicon sequencing source of variability. Spatial variability was evaluated using composite bulk soil cores at four sampling points covering 2500 m² per field. Geolocated soils were also collected on three sampling dates during the growing season to evaluate temporal variability. A technical variability threshold was determined for the soil DNA extraction variability with a delta of Shannon index of 0.142 and 0.390 and a weighted UniFrac distance of 0.081 and 0.364 for prokaryotes and fungi, respectively. We observed that technical variability was consistently similar or lower than the spatial and temporal variabilities in each of the microbial communities. Observed variability was greater for the diversity of fungi and the crop system has a strong effect on temporal and spatial variability.
{"title":"Spatial, temporal and technical variability in the diversity of prokaryotes and fungi in agricultural soils","authors":"T. Jeanne, Joël D’Astous-Pagé, R. Hogue","doi":"10.3389/fsoil.2022.945888","DOIUrl":"https://doi.org/10.3389/fsoil.2022.945888","url":null,"abstract":"Several studies have shown that Illumina MiSeq high-throughput sequencing can be used to measure the diversity of prokaryotes and fungal communities that provide ecosystem functions in agricultural soils. Pedoclimatic properties of soils, together with cropping systems and agricultural management practices, are major drivers of soil microbiome diversity. Their effects must be quantified and compared to technical variability to improve the relevance of observed effects and the indicators that may result from them. This study was conducted: 1) To assess the effects of three sources of technical variability on the soil prokaryotes and fungal diversity; 2) To identify a source of technical variability that can be used as a threshold to better assess crop management effects; 3) To evaluate the effects of spatial and temporal variability compare to a technical threshold in three crop management contexts, potato, corn/soybean and grassland. Technical variability was evaluated in a basis of sampling, soil DNA extraction and amplicon sequencing source of variability. Spatial variability was evaluated using composite bulk soil cores at four sampling points covering 2500 m² per field. Geolocated soils were also collected on three sampling dates during the growing season to evaluate temporal variability. A technical variability threshold was determined for the soil DNA extraction variability with a delta of Shannon index of 0.142 and 0.390 and a weighted UniFrac distance of 0.081 and 0.364 for prokaryotes and fungi, respectively. We observed that technical variability was consistently similar or lower than the spatial and temporal variabilities in each of the microbial communities. Observed variability was greater for the diversity of fungi and the crop system has a strong effect on temporal and spatial variability.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43103154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-02DOI: 10.3389/fsoil.2022.920142
L. Koutika
The hydrogen sulfide (H2S) deposition from oil exploitation occurring since 1969 may potentially affect bacterial communities in acacia and eucalyptus plantations of the Congolese coastal plains. These plantations have been implemented on previous native savannas to use the unsuitable soils for agriculture, provide pulp wood and fuel wood energy, and preserve the natural forests. Increased carbon (C) and nitrogen (N) stocks in stands containing acacia relative to baseline (eucalyptus) stocks have been reported. Phosphorus availability also improved in coarse particulate organic matter (4,000–250 µm) in afforested stands as compared to natural savannas. Investigation of the abundance of bacterial phyla by metabarcoding of the 16S rRNA bacterial gene in different stands of monocultures and mixed-species stands reveals the prevalence of Actinobacteria in all stands. This phylum is generally associated with the presence of sulfur in industrial areas and has a crucial role in organic matter decomposition. This may be linked to improved soil attributes (C, N, and P) and related to oil exploitation in addition to natural processes. This review shows, therefore, how potentially human activities may impact bacterial community composition, which may further change other soil attributes. It also acknowledges that the sustainability of forest plantations on inherently nutrient-poor soils strongly relies on interactions between soil functions, the environment, and human activities driven by soil organisms.
{"title":"How hydrogen sulfide deposition from oil exploitation may affect bacterial communities and the health of forest soils in Congolese coastal plains?","authors":"L. Koutika","doi":"10.3389/fsoil.2022.920142","DOIUrl":"https://doi.org/10.3389/fsoil.2022.920142","url":null,"abstract":"The hydrogen sulfide (H2S) deposition from oil exploitation occurring since 1969 may potentially affect bacterial communities in acacia and eucalyptus plantations of the Congolese coastal plains. These plantations have been implemented on previous native savannas to use the unsuitable soils for agriculture, provide pulp wood and fuel wood energy, and preserve the natural forests. Increased carbon (C) and nitrogen (N) stocks in stands containing acacia relative to baseline (eucalyptus) stocks have been reported. Phosphorus availability also improved in coarse particulate organic matter (4,000–250 µm) in afforested stands as compared to natural savannas. Investigation of the abundance of bacterial phyla by metabarcoding of the 16S rRNA bacterial gene in different stands of monocultures and mixed-species stands reveals the prevalence of Actinobacteria in all stands. This phylum is generally associated with the presence of sulfur in industrial areas and has a crucial role in organic matter decomposition. This may be linked to improved soil attributes (C, N, and P) and related to oil exploitation in addition to natural processes. This review shows, therefore, how potentially human activities may impact bacterial community composition, which may further change other soil attributes. It also acknowledges that the sustainability of forest plantations on inherently nutrient-poor soils strongly relies on interactions between soil functions, the environment, and human activities driven by soil organisms.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45385403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-02DOI: 10.3389/fsoil.2022.869136
Ouyang Yang, J. Reeve, J. Norton
Organic amendments are applied in organic farming systems to provide nutrients for crop uptake and to improve soil health. Compost is often favored over fresh manure for food safety reasons, while fresh manure can be a valuable source of readily available nitrogen (N). However, the potential for fresh versus composted manure to differentially affect soil microbial and N-cycling functional communities over multiple seasons remains unknown. We compared the effect of composted vs. fresh cattle manure on soil microbial communities using taxonomic and functional approaches. Soils were collected from field plots with three organic N treatments: control (no amendment), composted manure (compost, 224 kg/ha total N), and fresh manure (manure, 224 kg/ha total N) in an organic production system. Illumina amplicon sequencing was used to comprehensively assess the bacterial community (16S rRNA genes), fungal community (ITS), ureolytic community (ureC), chitinolytic community (chiA), bacterial ammonia oxidizers (AOB amoA), and nitrite oxidizers (Nitrospira nxrB). The results showed that both compost and manure treatment significantly changed the soil microbial communities. Manure had a stronger effect than compost on soil bacterial and fungal community composition, as well as on the ureolytic and chitinolytic communities, while compost treated soils had higher microbial richness than manure treated soils. Both taxonomic and functional approaches showed that the microbial community was more responsive to fresh manure than to compost. Manure treated soil also had more complex microbial interactions than compost treated soil. The abundance and community composition of N-cycling functional groups often played more limited roles than soil chemical properties (soil organic carbon, extractable organic carbon, and pH) in driving N-cycling processes. Results from our study may guide strategies for the management of organic amendments in organic farming systems and provide insights into the linkages between soil microbial communities and soil function.
{"title":"The quality of organic amendments affects soil microbiome and nitrogen-cycling bacteria in an organic farming system","authors":"Ouyang Yang, J. Reeve, J. Norton","doi":"10.3389/fsoil.2022.869136","DOIUrl":"https://doi.org/10.3389/fsoil.2022.869136","url":null,"abstract":"Organic amendments are applied in organic farming systems to provide nutrients for crop uptake and to improve soil health. Compost is often favored over fresh manure for food safety reasons, while fresh manure can be a valuable source of readily available nitrogen (N). However, the potential for fresh versus composted manure to differentially affect soil microbial and N-cycling functional communities over multiple seasons remains unknown. We compared the effect of composted vs. fresh cattle manure on soil microbial communities using taxonomic and functional approaches. Soils were collected from field plots with three organic N treatments: control (no amendment), composted manure (compost, 224 kg/ha total N), and fresh manure (manure, 224 kg/ha total N) in an organic production system. Illumina amplicon sequencing was used to comprehensively assess the bacterial community (16S rRNA genes), fungal community (ITS), ureolytic community (ureC), chitinolytic community (chiA), bacterial ammonia oxidizers (AOB amoA), and nitrite oxidizers (Nitrospira nxrB). The results showed that both compost and manure treatment significantly changed the soil microbial communities. Manure had a stronger effect than compost on soil bacterial and fungal community composition, as well as on the ureolytic and chitinolytic communities, while compost treated soils had higher microbial richness than manure treated soils. Both taxonomic and functional approaches showed that the microbial community was more responsive to fresh manure than to compost. Manure treated soil also had more complex microbial interactions than compost treated soil. The abundance and community composition of N-cycling functional groups often played more limited roles than soil chemical properties (soil organic carbon, extractable organic carbon, and pH) in driving N-cycling processes. Results from our study may guide strategies for the management of organic amendments in organic farming systems and provide insights into the linkages between soil microbial communities and soil function.","PeriodicalId":73107,"journal":{"name":"Frontiers in soil science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43607404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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