Soil Sciences

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Now showing 1 - 5 of 18
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    Microbial necromass carbon and nitrogen persistence are decoupled in agricultural grassland soils
    (Springer Nature, 2022-05-13) Buckeridge, Kate M.; Mason, Kelly E.; Ostle, Nick; McNamara, Niall P.; Grant, Helen K.; Whitaker, Jeanette
    Microbial necromass is an important component of soil organic matter, however its persistence and contribution to soil carbon sequestration are poorly quantified. Here, we investigate the interaction of necromass with soil minerals and compare its persistence to that of plant litter in grassland soils under low- and high-management intensity in northwest England. During a 1-year laboratory-based incubation, we find carbon mineralization rates are higher for plant leaf litter than root litter and necromass, but find no significant difference in carbon persistence after 1 year. During a field experiment, approximately two thirds of isotopically-labelled necromass carbon became mineral-associated within 3 days. Mineral-associated carbon declined more rapidly than nitrogen over 8 months, with the persistence of both enhanced under increased management intensity. We suggest that carbon mineralisation rates are decoupled from carbon persistence and that necromass carbon is less persistent than necromass nitrogen, with agricultural management intensity impacting carbon sequestration in grasslands.
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    Thresholds in aridity and soil carbon-to-nitrogen ratio govern the accumulation of soil microbial residues
    (Springer Nature, 2021-11-18) Hao, Zhiguo; Zhao, Yunfei; Wang, Xia; Wu, Jinhong; Jiang, Silong; Xiao, Jinjin; Wang, Kaichang; Zhou, Xiaohe; Liu, Huiying; Li, Jia; Sun, Yuxin
    Microbial moribunds after microbial biomass turnover (microbial residues) contribute to the formation and stabilization of soil carbon pools; however, the factors influencing their accumulation on a global scale remain unclear. Here, we synthesized data for 268 amino sugar concentrations (biomarkers of microbial residues) in grassland and forest ecosystems for meta-analysis. We found that soil organic carbon, soil carbon-to-nitrogen ratio, and aridity index were key factors that predicted microbial residual carbon accumulation. Threshold aridity index and soil carbon-to-nitrogen ratios were identified (~0.768 and ~9.583, respectively), above which microbial residues decreased sharply. The aridity index threshold was associated with the humid climate range. We suggest that the soil carbon-to-nitrogen ratio threshold may coincide with a sharp decrease in fungal abundance. Although dominant factors vary between ecosystem and climate zone, with soil organic carbon and aridity index being important throughout, our findings suggest that climate and soil environment may govern microbial residue accumulation.
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    Urban Soil Pollution by Heavy Metals: Effect of the Lockdown during the Period of COVID-19 on Pollutant Levels over a Five-Year Study
    (MDPI, 2023-03-20) Papadimou, Sotiria G.; Kantzou, Ourania-Despoina; Chartodiplomenou, Maria-Anna; Golia, Evangelia E.
    When residents of Volos, a city in central Greece, are trying to recall their daily life after the end of the quarantine due to COVID-19, the soil pollution survey provided valuable insights, which are compared with a 4-year study carried out in that area before the pandemic period. Using appropriate indices, namely contamination factor (CF), pollution load index (PLI), geo-accumulation index (Igeo), ecological risk factor (Er), and potential ecological risk index (RI), and using geostatistical tools, maps were constructed for each metal (Cu, Zn, Pb, Ni, Cd, Co, Cr, Mn). Variations in the values of the contamination indices showed a significant redistribution in pollutant load from areas previously polluted by high vehicle traffic and the activities of the main port to the residential areas, where the habitants have their homes and playgrounds. The study showed that Cu, Zn, Pb, and Co concentrations increased during the pandemic period by 10%, 22.7%, 3.7%, and 23.1%, respectively. Ni’s concentration remained almost constant, while Cd, Cr, and Mn concentrations were decreased by 21.6%, 22.2%, and 9.5%, respectively. Fluctuations in the concentrations and corresponding contamination and ecological indices of the elements can serve as a means for highlighting potential sources of pollution. Therefore, although the pandemic period created anxiety, stress, and economic hardship for citizens, it may prove to be a valuable tool for investigating the sources of pollution in urban soils. The study of these results could potentially lead to optimal ways for managing the environmental crisis and solve persistent problems that pose risks to both the soil environment and human health.
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    Silica and Biochar Amendments Improve Cucumber Growth under Saline Conditions
    (MDPI, 2023-03-12) Al-Toobi, Manar; Janke, Rhonda R.; Khan, Muhammad Mumtaz; Ahmed, Mushtaque; Al-Busaidi, Waleed M.; Rehman, Abdul
    Rapidly increasing salinization of arable land is a major threat to crop production globally, and the soil of regions with arid environments, such as Oman, are more prone to this menace. In this work, two complementary studies were carried out to evaluate the effect of soil amendments on soil physicochemical properties and growth of cucumber seedlings. In the first study, high- and low-saline soils were used with or without perlite. The amendments tested included mango wood biochar, silica, and biochar + silica, while no amendment was taken as the control. The second study included two cucumber cultivars and irrigation water with two salinity treatments, along with the same four soil amendments. The results showed that soil amendment with biochar alone or with silica enhanced the soil organic matter and NO3, P, and K concentration, while silica amendment substantially enhanced the soil Si level in both studies. Saline soil and irrigation water inhibited seedling emergence and plant growth in both experiments. However, the addition of biochar and silica alone or in combination increased the cucumber seedling dry weight from 39.5 to 77.3% under salt stress compared to the control. Likewise, silica and biochar + silica reduced the sap Na accumulation by 29–31.1% under high salinity. Application of biochar under high salinity resulted in 87.2% increase in sap K. Soil amendments with biochar and silica or their combination have the potential to reduce the adverse effect of salt stress on cucumber.
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    Soil Health Assessment and Management Framework for Water-Limited Environments: Examples from the Great Plains of the USA
    (MDPI, 2023-03-02) Ghimire, Rajan; Thapa, Vesh R.; Acosta-Martinez, Veronica; Schipanski, Meagan; Slaughter, Lindsey C.; Fonte, Steven J.; Shukla, Manoj K.; Bista, Prakriti; Angadi, Sangamesh V.; Mikha, Maysoon M.; Adebayo, Olufemi; Strohm, Tess Noble
    Healthy soils provide the foundation for sustainable agriculture. However, soil health degradation has been a significant challenge for agricultural sustainability and environmental quality in water-limited environments, such as arid and semi-arid regions. Soils in these regions is often characterized by low soil organic matter (SOM), poor fertility, and low overall productivity, thus limiting the ability to build SOM. Soil health assessment frameworks developed for more productive, humid, temperate environments typically emphasize building SOM as a key to soil health and have identified the best management practices that are often difficult to implement in regions with water limitations. This study reviewed existing soil health assessment frameworks to assess their potential relevance for water-limited environments and highlights the need to develop a framework that links soil health with key ecosystem functions in dry climates. It also discusses management strategies for improving soil health, including tillage and residue management, organic amendments, and cropping system diversification and intensification. The assessment of indicators sensitive to water management practices could provide valuable information in designing soil health assessment frameworks for arid and semi-arid regions. The responses of soil health indicators are generally greater when multiple complementary soil health management practices are integrated, leading to the resilience and sustainability of agriculture in water-limited environments.