Journal articles on the topic 'Soils – Tropics – Composition'
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1
van der Velden, Nic, J. W. Ferry Slik, Yue-Hua Hu, Guoyu Lan, Luxian Lin, XiaoBao Deng, and Lourens Poorter. "Monodominance of Parashorea chinensis on fertile soils in a Chinese tropical rain forest." Journal of Tropical Ecology 30, no. 4 (June 23, 2014): 311–22. http://dx.doi.org/10.1017/s0266467414000212.
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Abstract:Monodominance in the tropics is often seen as an unusual phenomenon due to the normally high diversity in tropical rain forests. Here we studied Parashorea chinensis H. Wang (Dipterocarpaceae) in a seasonal tropical forest in south-west China, to elucidate the mechanisms behind its monodominance. Twenty-eight 20 × 20-m plots were established in monodominant and mixed forest in Xishuangbanna, Yunnan province. All individuals ≥1 cm stem diameter and 16 soil variables were measured. Parashorea chinensis forest had a significantly higher mean tree dbh compared with mixed forest. Diversity did not differ significantly between the two forest types. However, within monodominant patches, all diversity indices decreased with an increase in P. chinensis dominance. Floristic composition of P. chinensis forest did differ significantly from the mixed forest. These differences were associated with more fertile soils (significantly higher pH, Mn, K and lower carbon pools and C:N ratio) in the P. chinensis forest than the mixed forest. In contrast to current paradigms, this monodominant species is not associated with infertile, but with fertile soils. Parashorea chinensis seems to be especially associated with high manganese concentrations which it can tolerate, and with edaphic conditions (water, K) that allow this tall and exposed emergent species to maintain its water balance. This is in contrast with most previous studies on monodominance in the tropics that found either no effect of soil properties, or predict associations with nutrient-poor soils.
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Oliveira, Luiz Antônio de. "CARACTERIZAÇÃO DOS LATOSSOLOS DA CHAPADA DE ARAGUARI: MINERAIS ARGILOSOS, GRANULOMETRIA E EVOLUÇÃO." Caminhos de Geografia 4, no. 8 (February 28, 2003): 20–37. http://dx.doi.org/10.14393/rcg4815302.
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The mineralogical composition of the latosols in the study area as determined by X-ray diffraction. Kaolinite and goethite is the dominant mineral in all profile (dark red, red-yellow and lateritic soils). Gibbsite is a common mineral present in the upper part of the profile (dark red and redyellow soils), while in the lateritic soil occur only in the "matriz� fraction. Hematite happens in the topsoils (dark red and red-yellow soils). Quartz dominates the coarse fraction in all materials and shows a higher variability in sizes, although it is predominantly fine sand-size. Anatase were also detected in the topsoil. The mineralogical composition of the materials indicates a high degree of weathering of the parent material, wich caracteristic for oxisols in the humid tropics.
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Salawu, M. B., T. Acamovic, C. S. Stewart, F. D. DeB. Hovell, and R. L. Roothaert. "Chemical composition and in vitro degradability of different parts of Calliandra calothyrsus from Kenya." Proceedings of the British Society of Animal Science 1997 (1997): 72. http://dx.doi.org/10.1017/s1752756200595131.
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Calliandra calothyrsus is a promising tropical leguminous browse, native to South America, but now planted in most parts of the tropics and subtropics. It is a fast growing plant, rich in proteins and can do well on poor soils (NRC, 1983). Its high content of condensed tannins has however limited its use as a feed for ruminants. The chemical composition and degradability in vitro in a consecutive batch culture (CBC) system were studied.
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Lyon, Steve W., Benjamin M. C. Fischer, Laura Morillas, Johanna Rojas Conejo, Ricardo Sánchez-Murillo, Andrea Suárez Serrano, Jay Frentress, Chih-Hsin Cheng, Monica Garcia, and Mark S. Johnson. "On the Potential of Biochar Soil Amendments as a Sustainable Water Management Strategy." Sustainability 14, no. 12 (June 8, 2022): 7026. http://dx.doi.org/10.3390/su14127026.
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Biochar has been put forward as a potential technology that could help achieve sustainable water management in agriculture through its ability to increase water holding capacity in soils. Despite this opportunity, there are still a limited number of studies, especially in vulnerable regions like the tropics, quantifying the impacts of biochar on soil water storage and characterizing the impacts of biochar additions on plant water composition. To address this critical gap, we present a case study using stable water isotopes and hydrometric data from melon production in tropical agriculture to explore the hydrological impacts of biochar as a soil amendment. Results from our 10-week growing season experiment in Costa Rica under drip irrigation demonstrated an average increase in volumetric soil moisture content of about 10% with an average moisture content of 25.4 cm3 cm−3 versus 23.1 cm3 cm−3, respectively, for biochar amended plots compared with control plots. Further, there was a reduction in the variability of soil matric potential for biochar amended plots compared with control plots. Our isotopic investigation demonstrated that for both biochar and control plots, there was a consistent increase (or enrichment) in isotopic composition for plant materials moving from the roots, where the average δ18O was −8.1‰ and the average δ2H was −58.5‰ across all plots and samples, up through the leaves, where the average δ18O was 4.3‰ and the average δ2H was 0.1‰ across all plots and samples. However, as there was no discernible difference in isotopic composition for plant water samples when comparing across biochar and control plots, we find that biochar did not alter the composition of water found in the melon plant material, indicating that biochar and plants are not competing for the same water sources. In addition, and through the holistic lens of sustainability, biochar additions allowed locally sourced feedstock carbon to be directly sequestered into the soil while improving soil water availability without jeopardizing production for the melon crop. Given that most of the expansion and intensification of global agricultural production over the next several decades will take place in the tropics and that the variability of tropical water cycling is expected to increase due to climate change, biochar amendments could offer a pathway forward towards sustainable tropical agricultural water management.
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Piperno, Dolores R., and Peter Becker. "Vegetational History of a Site in the Central Amazon Basin Derived from Phytolith and Charcoal Records from Natural Soils." Quaternary Research 45, no. 2 (March 1996): 202–9. http://dx.doi.org/10.1006/qres.1996.0020.
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AbstractAnalysis of phytoliths and macroscopic charcoal from natural soils near Manaus, Brazil shows that the central Amazonian terra firme forest has not been stable during the Holocene. Phytolith taxonomic composition and radiocarbon ages indicate that a closed forest has continuously existed in the area since at least 4600 yr B.P., but that forest composition and species abundance changed significantly sometime during the Holocene Epoch. There is no evidence that the vegetation experienced swidden cultivation. The distribution and dates of the charcoal in the soils indicate that forest fires between 1795 and 550 yr B.P. burned an area of about 200 hectares. Vegetational changes and fires appear to be a result of climatic drying that may have affected large areas of the Amazon Basin over the past 5000 to 7000 years. Soil phytolith analysis is a promising tool for the study of environmental history in the humid tropics and may reduce the previous dependence on lake and swamp sediments, at least for the Holocene Epoch.
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Foran, BD, G. Bastin, and B. Hill. "The pasture dynamics and management of two rangeland communities in the Victoria River District of the Northern Territory." Rangeland Journal 7, no. 2 (1985): 107. http://dx.doi.org/10.1071/rj9850107.
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The use of destocking as a means of promoting pasture recovery was evaluated on two important rangeland types of the semi-arid tropics of north west Australia. Recovery on eroded calcareous red soils was substantial within five years. Standing biomass and species composition, particularly the contribution of the major forage grass Enneapogon spp., was then similar to areas in good condition. However, an exotic shrub, Calotropls procera, invaded the area during the study. Grazing limited its increase to 200 bushes ha-1 compared to unstocked areas where it increased to 1,000 bushes ha-1. Destocking had no effect on cracking clay soils in good condition, dominated by Chrysopogon fallax and Iseilema fragile. An index based on similarity measures of herbage standing biomass, followed closely the course of recovery of the eroded calcareous soil during the period. There is a need for range condition assessment and the development and application of appropriate pasture management strategies for the whole district.
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Nadel, R. L., M. C. Scholes, and M. J. Byrne. "Slash burning, faunal composition, and nutrient dynamics in a Eucalyptus grandis plantation in South AfricaThis article is one of a selection of papers published in the Special Forum on Towards Sustainable Forestry — The Living Soil: Soil Biodiversity and Ecosystem Function." Canadian Journal of Forest Research 37, no. 2 (February 2007): 226–35. http://dx.doi.org/10.1139/x06-287.
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The sustainability of exotic commercial plantations is dependent on the conservation of soil nutrients, especially on the ancient, leached soils of the tropics, particularly when limited fertilization is practiced. In Eucalyptus grandis W. Hill ex Maid. plantations in South Africa, the site is usually burned following harvest and prior to replanting, potentially causing a disruption of soil faunal function and losses of nutrients associated with burning and removal of slash residues. The aim was to study the effect of fire on nutrient dynamics and invertebrate faunal composition. The in situ nitrogen and phosphorus mineralization rates and invertebrate faunal composition were measured in six randomly located plots — three burned and three unburned — prior to and after a low-intensity fire. Results indicate that within the burned plots, phosphorus availability was enhanced 10-fold within the first month following the fire. Invertebrate faunal diversity was low both prior to and after burning, with ants constituting the highest number. Invertebrate faunal composition was more markedly influenced by season than by the fire, with millipedes present in the majority of plots in spring and ants dominating in summer.
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Albuquerque, A. G. B. M., T. O. Ferreira, G. N. Nóbrega, R. E. Romero, V. S. Souza Júnior, A. J. A. Meireles, and X. L. Otero. "Soil genesis on hypersaline tidal flats (apicum ecosystem) in a tropical semi-arid estuary (Ceará, Brazil)." Soil Research 52, no. 2 (2014): 140. http://dx.doi.org/10.1071/sr13179.
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Wetland soils, especially those under a semi-arid climate, are among the least studied soils in the tropics. The hypersaline tidal flats on the north-eastern Brazilian coast, locally named apicum, are coastal wetland ecosystems in the peripheral portions of semi-arid estuaries. Despite their great ecological importance, they have been highly impacted by anthropogenic activities. Morphological and analytical data of six soil profiles, representative of the different coastal compartments (mangroves, apicum and coastal tablelands) of the north-eastern Brazilian coast, were examined to better understand the pedogenesis of apicum soils. The hypersaline tidal flat soils were classified as Typic Fluvaquents and Typic Sulfaquents with the following main characteristics: predominance of sand fraction (62–77%); presence of high-activity clays (>24 cmolc kg–1 clay); clay fraction comprising kaolinite, illite, smectite and an interstratified smectite/illite; exchangeable complex dominated by Na+ (ESP ≥15%); elevated levels of salinity (electrical conductivity, EC 25–44 dS m–1); alkaline pH values (7.5–9.5). The sandy texture and quartz-dominated composition of the hypersaline, tidal flat soils indicate a pedogenesis associated with the superficial addition of mineral material. This upbuilding process would have lowered the watertable (relatively to the ground level) and decreased the flooding frequency by the tides, favouring salinisation and solonisation processes at the hypersaline tidal flats. Furthermore, the still-existing hydromorphism would have promoted the maintenance of gleisation and sulfidisation. The presence of pyrite on the hyper-saline tidal flat soils further corroborates the formation of apicum soils from/over buried mangroves.
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Pereira-De-Oliveira, Luiz, Lucio Macedo, José Neto, Dellane Santos, and Hugo Silva. "Viability of lateritic soil as alkaline activated precursor." MATEC Web of Conferences 274 (2019): 01004. http://dx.doi.org/10.1051/matecconf/201927401004.
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This study investigates the disposal of lateritic soil available in the state of Maranhao, Brazil, to be used as a natural precursor of alkaline activated material. Lateritic soils are formed in the tropics through weathering processes that favour the formation of iron, aluminium and may contain a large amount of quartz and kaolinite. The quality of laterite for this application may vary significantly depending on both geographic location and depth of a quarry. The identification of quarry locals was carried out in this work, together with a disposal volume estimation considering economic issues about exploration techniques. A comparison of the chemical composition of the lateritic soil of the state of Maranhao with those related in the literature is used to outline the feasibility of using this natural material as precursor of alkaline activated cements. It is concluded that the lateritic soil availability, as well as their characteristics, can enable the development of alkaline activated materials as a future local building material and environmentally friendly.
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Williams, J. E., M. P. Scheele, P. F. J. van Velthoven, J. P. Cammas, V. Thouret, C. Galy-Lacaux, and A. Volz-Thomas. "The influence of biogenic emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study." Atmospheric Chemistry and Physics Discussions 9, no. 2 (April 28, 2009): 10367–427. http://dx.doi.org/10.5194/acpd-9-10367-2009.
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Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that biogenic emissions from the African continent exert on the composition of the tropopause in the tropical region. For this purpose we have applied two recently developed biogenic emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathiére et al., 2006) whose seasonality and temporal distribution for isoprene, biogenic NO and biogenic volatile organic compounds is markedly different. The use of the climatological values for biogenic emissions provided by Lathiére et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~5–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For biogenic volatile organic C1 to C3 species released from Africa the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean. Comparisons against a range of different measurements indicate that applying the climatology of Lathiére et al. (2006) improves the performance of TM4 for 2006 in the tropics.
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Williams, J. E., M. P. Scheele, P. F. J. van Velthoven, J. P. Cammas, V. Thouret, C. Galy-Lacaux, and A. Volz-Thomas. "The influence of biogenic emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study." Atmospheric Chemistry and Physics 9, no. 15 (August 11, 2009): 5729–49. http://dx.doi.org/10.5194/acp-9-5729-2009.
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Abstract. We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that biogenic emissions from the African continent exert on the composition of the troposphere in the tropical region. For this purpose we have applied two recently developed biogenic emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathière et al., 2006) whose seasonality and temporal distribution for biogenic emissions of isoprene, other volatile organic compounds and NO is markedly different. The use of the 12 year average values for biogenic emissions provided by Lathière et al. (2006) results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in the tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO3 and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH4 and CO by ~1.5% and ~4%, respectively. Comparisons against a range of different measurements indicate that applying the 12 year average of Lathière et al. (2006) improves the performance of TM4_AMMA for 2006 in the tropics. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~2–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For biogenic volatile organic C1 to C3 species released from Africa, the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and has a large influence on the organic composition of the troposphere over the tropical Atlantic Ocean.
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Gomes, Newton C. Marcial, Olajire Fagbola, Rodrigo Costa, Norma Gouvea Rumjanek, Arno Buchner, Leda Mendona-Hagler, and Kornelia Smalla. "Dynamics of Fungal Communities in Bulk and Maize Rhizosphere Soil in the Tropics." Applied and Environmental Microbiology 69, no. 7 (July 2003): 3758–66. http://dx.doi.org/10.1128/aem.69.7.3758-3766.2003.
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ABSTRACT The fungal population dynamics in soil and in the rhizospheres of two maize cultivars grown in tropical soils were studied by a cultivation-independent analysis of directly extracted DNA to provide baseline data. Soil and rhizosphere samples were taken from six plots 20, 40, and 90 days after planting in two consecutive years. A 1.65-kb fragment of the 18S ribosomal DNA (rDNA) amplified from the total community DNA was analyzed by denaturing gradient gel electrophoresis (DGGE) and by cloning and sequencing. A rhizosphere effect was observed for fungal populations at all stages of plant development. In addition, pronounced changes in the composition of fungal communities during plant growth development were found by DGGE. Similar types of fingerprints were observed in two consecutive growth periods. No major differences were detected in the fungal patterns of the two cultivars. Direct cloning of 18S rDNA fragments amplified from soil or rhizosphere DNA resulted in 75 clones matching 12 dominant DGGE bands. The clones were characterized by their HinfI restriction patterns, and 39 different clones representing each group of restriction patterns were sequenced. The cloning and sequencing approach provided information on the phylogeny of dominant amplifiable fungal populations and allowed us to determine a number of fungal phylotypes that contribute to each of the dominant DGGE bands. Based on the sequence similarity of the 18S rDNA fragment with existing fungal isolates in the database, it was shown that the rhizospheres of young maize plants seemed to select the Ascomycetes order Pleosporales, while different members of the Ascomycetes and basidiomycetic yeast were detected in the rhizospheres of senescent maize plants.
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McCown, RL. "Being realistic about no-tillage, legume ley farming for the Australian semi-arid tropics." Australian Journal of Experimental Agriculture 36, no. 8 (1996): 1069. http://dx.doi.org/10.1071/ea9961069.
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There is a long tradition of expectation that, in time, land use in the better-endowed areas of Australia's semi-arid tropics would intensify from beef production on grassy woodlands to broadacre production of dryland crops. However, successive development attempts have yet to result in a substantial field crop industry. This paper reflects on a recent 20-year research and development episode in which ley farming, so successful in the wheat-sheep zone of southern Australia, was adapted and trialed in the tropical north. The system tested in the tropics was one which featured (i) coarse grain crops in rotation with legume leys and (ii) cattle grazing native pasture in the crop growing season and ley and crop residues in the dry season. It can be concluded that this system is technically successful. But compared with the ley system in southern Australia, the benefits of pasture legumes are less efficiently captured, both in the animal and the crop production enterprises. In addition, in this climate and on these soils, pastures with the high legume composition needed to substantially substitute for nitrogen fertiliser in the crop phase pose a serious threat of soil acidification. In contrast to legume leys, the advantage of no-tillage, mulch farming practices over conventional cultivation is much greater in this semi-arid tropical region than in temperate or Mediterranean areas: by slowing evaporation, mulch is often crucial in reducing high temperature injury or impedance to emerging seedlings as well as reducing the deleterious effects of intensive summer rainfall. But even with this improvement the climatic risks in dryland grain cropping remain a strong deterrent to crop industry development. Today, the findings from past experimentation, accrued farming experience, and new information products combine to provide what seem to be more realistic expectations for agriculture in this region. Even with the 'best' technology, this region suffers comparative disadvantage with respect to dryland field crop production and marketing. However, the region enjoys comparative advantages in the production of several other types of commodities, and a more realistic approach to 'Research and Development' includes a shift of resources toward activities with production and marketing advantages.
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Brasseur, Guy P., Martin Schultz, Claire Granier, Marielle Saunois, Thomas Diehl, Michael Botzet, Erich Roeckner, and Stacy Walters. "Impact of Climate Change on the Future Chemical Composition of the Global Troposphere." Journal of Climate 19, no. 16 (August 15, 2006): 3932–51. http://dx.doi.org/10.1175/jcli3832.1.
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Abstract A global chemical transport model of the atmosphere [the Model for Ozone and Related Tracers, version 2 (MOZART-2)] driven by prescribed surface emissions and by meteorological fields provided by the ECHAM5/Max Planck Institute Ocean Model (MPI-OM-1) coupled atmosphere–ocean model is used to assess how expected climate changes (2100 versus 2000 periods) should affect the chemical composition of the troposphere. Calculations suggest that ozone changes resulting from climate change only are negative in a large fraction of the troposphere because of enhanced photochemical destruction by water vapor. In the Tropics, increased lightning activity should lead to larger ozone concentrations. The magnitude of the climate-induced ozone changes in the troposphere remains smaller than the changes produced by enhanced anthropogenic emissions when the Special Report on Emission Scenarios (SRES) A2P is adopted to describe the future evolution of these emissions. Predictions depend strongly on future trends in atmospheric methane levels, which are not well established. Changes in the emissions of NOx by bacteria in soils and of nonmethane hydrocarbons by vegetation associated with climate change could have a significant impact on future ozone levels.
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Hargis, Hailey, Sybil G. Gotsch, Philipp Porada, Georgianne W. Moore, Briana Ferguson, and John T. Van Stan. "Arboreal Epiphytes in the Soil-Atmosphere Interface: How Often Are the Biggest “Buckets” in the Canopy Empty?" Geosciences 9, no. 8 (August 5, 2019): 342. http://dx.doi.org/10.3390/geosciences9080342.
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Arboreal epiphytes (plants residing in forest canopies) are present across all major climate zones and play important roles in forest biogeochemistry. The substantial water storage capacity per unit area of the epiphyte “bucket” is a key attribute underlying their capability to influence forest hydrological processes and their related mass and energy flows. It is commonly assumed that the epiphyte bucket remains saturated, or near-saturated, most of the time; thus, epiphytes (particularly vascular epiphytes) can store little precipitation, limiting their impact on the forest canopy water budget. We present evidence that contradicts this common assumption from (i) an examination of past research; (ii) new datasets on vascular epiphyte and epi-soil water relations at a tropical montane cloud forest (Monteverde, Costa Rica); and (iii) a global evaluation of non-vascular epiphyte saturation state using a process-based vegetation model, LiBry. All analyses found that the external and internal water storage capacity of epiphyte communities is highly dynamic and frequently available to intercept precipitation. Globally, non-vascular epiphytes spend <20% of their time near saturation and regionally, including the humid tropics, model results found that non-vascular epiphytes spend ~1/3 of their time in the dry state (0–10% of water storage capacity). Even data from Costa Rican cloud forest sites found the epiphyte community was saturated only 1/3 of the time and that internal leaf water storage was temporally dynamic enough to aid in precipitation interception. Analysis of the epi-soils associated with epiphytes further revealed the extent to which the epiphyte bucket emptied—as even the canopy soils were often <50% saturated (29–53% of all days observed). Results clearly show that the epiphyte bucket is more dynamic than currently assumed, meriting further research on epiphyte roles in precipitation interception, redistribution to the surface and chemical composition of “net” precipitation waters reaching the surface.
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Gomes, Eliane A., Ubiraci G. P. Lana, John F. Quensen, Sylvia M. de Sousa, Christiane A. Oliveira, Jiarong Guo, Lauro J. M. Guimarães, and James M. Tiedje. "Root-Associated Microbiome of Maize Genotypes with Contrasting Phosphorus Use Efficiency." Phytobiomes Journal 2, no. 3 (January 2018): 129–37. http://dx.doi.org/10.1094/pbiomes-03-18-0012-r.
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Marginal soil fertility, soil acidity, aluminum toxicity, and a generalized low level of available nutrients, especially phosphorus (P), are major limiting factors to maize production in highly weathered oxisols that are prominent in the tropics. Plants have evolved several strategies to improve P acquisition, including the ability to associate with soil microorganisms that potentially enhance P uptake and plant nutrition. We investigated the effect of two maize genotypes with contrasting P use efficiency and their hybrid, grown in soils with two P levels, on bacterial and fungal community structures in the root and the rhizosphere. We found that a significant fraction of bacterial and fungal diversity could be attributed to the host genotype, but in general, the soil P level was the major driver of microbiome structure followed by plant compartment (rhizosphere versus directly root associated). Slow-growing bacterial taxa increased in the low P soil, whereas fast-growing taxa were enriched in high P soil. The low P soil had a positive effect on arbuscular mycorrhizal fungi abundance, as expected, particularly inside the root. On the other hand, our results did not support selection for microbes associated to plant growth promoting and P solubilization based on P availability. Taken together, our results expand knowledge of which microbial groups are favored in P-deficient oxisol and suggest that P fertilization significantly impacts the species composition and diversity indices of bacteria and fungi communities, both inside the roots and in the rhizosphere.
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Coates, D. B., and R. P. Le Feuvre. "Diet composition of cattle grazing Stylosanthes - grass pastures in the seasonally dry tropics: the effect of phosphorus as fertiliser or supplement." Australian Journal of Experimental Agriculture 38, no. 1 (1998): 7. http://dx.doi.org/10.1071/ea97031.
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Summary. The effect of phosphorus (P) on diet selection in cattle grazing pastures based on Stylosanthes hamata cv. Verano andS. scabra cv. Seca in the seasonally dry tropics was studied in 3 grazing trials on soils with inherently low P status ( 5 µg/g bicarbonate-extractable P). The contribution of Stylosanthes (stylo) to diets was estimated at regular intervals (approximately monthly) using carbon isotope analysis of faeces. Feeding P supplement increased the proportion of stylo in the diet but the effect was seasonal and variable, being most pronounced during the late wet and early dry seasons when dietary stylo proportions are usually highest. The results indicated that P supplement influenced diet selection through its effect on dietary P status such that cattle with a deficiency of dietary P select a lower proportion of stylo than those with higher P intakes. The effect of fertiliser P on dietary stylo content was also variable. The dominant effect was via fertiliser-induced changes in pasture botanical composition. Higher stylo proportions in the diet of heifers grazing unfertilised pasture compared with those grazing fertilised pasture were associated with increasing stylo dominance in unfertilised pastures as opposed to grass dominance in fertilised pastures. At the same time there was evidence of a fertiliser treatment effect that was consistent with dietary P status influencing diet composition. In the grass-dominant pastures, unsupplemented cattle on low P pasture selected less stylo than those grazing pastures of higher P status due to more frequent fertilising but there was no difference where P supplement was fed. A strong seasonal preference for grass early in the wet season, reinforced by a generally reduced preference for stylo in cattle with diets deficient in P, probably hastened the development of stylo dominance in unfertilised pasture where P supplement was not fed.
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Poungparn, Sasitorn, Akira Komiyama, Suthathip Umnouysin, Chadtip Rodtassana, Tanuwong Sangtiean, Chatree Maknual, Tamanai Pravinvongvuthi, Vilanee Suchewaboripont, and Shogo Kato. "Ten-Year Estimation of Net Primary Productivity in a Mangrove Forest under a Tropical Monsoon Climate in Eastern Thailand: Significance of the Temperature Environment in the Dry Season." Forests 11, no. 9 (September 15, 2020): 987. http://dx.doi.org/10.3390/f11090987.
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Mangrove forests play crucial roles in the coastal ecosystems of the tropics. Few studies have addressed long-term changes in the net primary productivity (NPP) of mangroves in relation to the tropical monsoon climate. We conducted a tree census from 2008 to 2018 in a permanent plot at a secondary mangrove forest under the tropical monsoon climate of Eastern Thailand. During this period, the mortality of fast-growing species and the increasing number of newly recruited trees revealed a temporal change in the plant composition and distribution. Total tree biomass linearly increased from 283.64 to 381.72 t·ha−1 during the study period. The NPP was calculated by using the summation method, which included fine root production. The NPP ranged from 21.19 to 29.04 t·ha−1·yr−1. The fluctuation in NPP and its components were analyzed in relation to climatic factors by the linear regression model. The NPP did not relate with the annual climatic factors, such as the mean temperature and annual rainfall. However, both increments in the basal area and living tree biomass, which is a major component of NPP, were negatively related with the maximum and mean monthly temperatures in the dry season. The annual mortality rate related positively with annual rainfall and the maximum monthly temperature in the dry season. Linear regression analyses showed that some major components of NPP were chiefly affected by the temperature environment in the dry season. These results indicated that the weather in the dry season was largely restricting the mangrove NPP due to effects on the saline water dynamics of the soils under the tropical monsoon climate, which were revealed by our recent study. It implies that the hot-dry season may lead to high mortality, long-term reduction in the increment of living-trees biomass, and thus lowered the ability to maintain high NPP of mangrove forests over the long-term.
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Ferreira, J., C. E. Reeves, J. G. Murphy, L. Garcia-Carreras, D. J. Parker, and D. E. Oram. "Isoprene emissions modelling for West Africa using MEGAN." Atmospheric Chemistry and Physics Discussions 10, no. 3 (March 11, 2010): 6923–53. http://dx.doi.org/10.5194/acpd-10-6923-2010.
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Abstract. Isoprene emissions are the largest source of reactive carbon to the atmosphere, with the tropics being a major source region. These natural emissions are expected to change with changing climate and human impact on land use. As part of the African Monsoon Multidisciplinary Analyses (AMMA) project the Model of Emissions of Gases and Aerosols from Nature (MEGAN) has been used to estimate the spatial and temporal distribution of isoprene emissions over the West African region. During the AMMA field campaign, carried out in July and August 2006, isoprene mixing ratios were measured on board the FAAM BAe-146 aircraft. These data have been used to evaluate the model performance. MEGAN was firstly applied to a large area covering much of West Africa from the Gulf of Guinea in the south to the desert in the north and was able to capture the large scale spatial distribution of isoprene emissions as inferred from the observed isoprene mixing ratios. In particular the model captures the transition from the forested area in the south to the bare soils in the north, but some discrepancies have been identified over the bare soil, mainly due to the emission factors used. Sensitivity analyses were performed to assess the model response to changes in driving parameters, namely Leaf Area Index (LAI), Emission Factors (EF), temperature and solar radiation. A high resolution simulation was made of a limited area south of Niamey, Niger, where the higher concentrations of isoprene were observed. This is used to evaluate the model's ability to simulate smaller scale spatial features and to examine the influence of the driving parameters on an hourly basis through a case study of a flight on 17 August 2006. This study highlights the complex interactions between land surface processes and the meteorological dynamics and chemical composition of the PBL. This has implications for quantifying the impact of biogenic emissions on the atmospheric composition over West Africa and any changes that may occur with changing climate.
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Ferreira, J., C. E. Reeves, J. G. Murphy, L. Garcia-Carreras, D. J. Parker, and D. E. Oram. "Isoprene emissions modelling for West Africa: MEGAN model evaluation and sensitivity analysis." Atmospheric Chemistry and Physics 10, no. 17 (September 7, 2010): 8453–67. http://dx.doi.org/10.5194/acp-10-8453-2010.
Full textAbstract:
Abstract. Isoprene emissions are the largest source of reactive carbon to the atmosphere, with the tropics being a major source region. These natural emissions are expected to change with changing climate and human impact on land use. As part of the African Monsoon Multidisciplinary Analyses (AMMA) project the Model of Emissions of Gases and Aerosols from Nature (MEGAN) has been used to estimate the spatial and temporal distribution of isoprene emissions over the West African region. During the AMMA field campaign, carried out in July and August 2006, isoprene mixing ratios were measured on board the FAAM BAe-146 aircraft. These data have been used to make a qualitative evaluation of the model performance. MEGAN was firstly applied to a large area covering much of West Africa from the Gulf of Guinea in the south to the desert in the north and was able to capture the large scale spatial distribution of isoprene emissions as inferred from the observed isoprene mixing ratios. In particular the model captures the transition from the forested area in the south to the bare soils in the north, but some discrepancies have been identified over the bare soil, mainly due to the emission factors used. Sensitivity analyses were performed to assess the model response to changes in driving parameters, namely Leaf Area Index (LAI), Emission Factors (EF), temperature and solar radiation. A high resolution simulation was made of a limited area south of Niamey, Niger, where the higher concentrations of isoprene were observed. This is used to evaluate the model's ability to simulate smaller scale spatial features and to examine the influence of the driving parameters on an hourly basis through a case study of a flight on 17 August 2006. This study highlights the complex interactions between land surface processes and the meteorological dynamics and chemical composition of the PBL. This has implications for quantifying the impact of biogenic emissions on the atmospheric composition over West Africa and any changes that may occur with changing climate.
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Hirpa, L., R. Nigussie-Dechassa, G. Setegn, and G. Bultosa. "Chemical quality of common beans as influenced by genotype and aluminium rates under two soil liming regimes." African Journal of Food, Agriculture, Nutrition and Development 15, no. 69 (March 30, 2015): 9872–91. http://dx.doi.org/10.18697/ajfand.69.13560.
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Soil acidity affects seed yield and crop quality negatively due to aluminium toxicity in most humid tropics where the crop is cultivated for food and cash income by smallholder farmers. This study was conducted to assess the effect of different exchangeable aluminium concentrations on bean chemical quality of two common bean genotypes grown on lime-treated and lime-untreated soils. Factorial combinations of five aluminium rates (0.0, 12.5, 25.0, 50.0, and 100.0 mg Al/ kg soil) and two common bean genotypes (New BILFA 58 and Roba 1) were laid out in a completely randomized design with three replications. For each treatment, four plants were raised per pot in the vegetation hall of Nekemte Soil Laboratory, western Ethiopia. The experiment was established in two sets: lime-treated soil and lime-untreated soil. The results revealed that aluminium toxicity caused major changes in the composition of the common beans. Significant differences (P < 0.01) were found among the different aluminium rates and between the two genotypes for bean crude protein, crude fibre, crude fat, and ash, carbohydrate, calcium, magnesium, and aluminium contents under both liming regimes. The interaction of aluminium and genotype also influenced most of the bean chemical quality attributes negatively. New BILFA 58 (acidic soil tolerant genotype) had better bean chemical quality attributes (except aluminium and condensed tannins contents) than Roba 1 (acidic soil sensitive genotype) under both liming regimes. On the average, lime application increased bean crude protein, crude fat, ash, and calcium contents by 4.1%, 20.7%, 7.9%, and 11.7%, respectively. However, it decreased bean crude fibre and aluminium contents. Bean carbohydrate and condensed tannin contents of the genotypes increased in response to increasing aluminium application under both liming regimes. The total ash, which is an indirect indicator of the mineral content of foodstuffs, was found to be higher for New BILFA 58 than Roba 1 under both liming regimes. In conclusion, the results of this study have demonstrated that increased soil aluminium contents have significant negative effects on common bean quality, but integrated use of tolerant genotypes and application of lime can simultaneously alleviate the problem of low yield and reduced bean nutritional quality of the crop.
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Thanachit, Suphicha, Anchalee Suddhiprakarn, Irb Kheoruenromne, and Robert J. Gilkes. "The geochemistry of soils on a catena on sedimentary rock at Nam Phong, north-east Thailand." Soil Research 44, no. 2 (2006): 143. http://dx.doi.org/10.1071/sr05030.
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The elemental composition of size fractions of soils on the Nam Phong catena, north-east Thailand, has been determined. The catena can be divided into 6 geomorphic positions: summit, shoulder, upper midslope, lower midslope, footslope and toeslope positions where soils have developed on sedimentary rocks under a tropical savannah climate. Factor analysis was used to interpret the large dataset and to determine profile and spatial trends in geochemistry. Silica is the major component of the soils on this catena, reflecting the presence of much quartz in the silt and sand fractions in soils at all landscape positions. Smaller amount of Al and Fe are also present; these elements are associated with the presence of kaolin and iron oxides. Factor analysis shows systematic differences in chemical composition between soils on higher positions and the soil on the lowest position in the landscape. Small variations in the chemical compositions of the whole soil, fine sand and silt between upslope soils are recognised. Soils on the summit, shoulder, midslope, and footslope exhibit little within-profile variation in chemical composition and the compositions of the profiles overlap closely. The Al affinity group (Al, Co, Ca, Mg, K, Sr, Cs, Rb, Ga, Zn, Ni, Li, Mn, Ti) increases in abundance in the toeslope soil, which is clearly different in chemical composition from the soils on higher positions. For the clay fraction, the differences in concentration of both the Si group (Si, Ni, Mn, Co, Mg, K, Ba, Pb) and Ca group (Ca, Zn, Cu, Sr, Cr, P) result in soils on toeslope and footslope positions being distinctly different from upslope soils, which have similar compositions. Soils at all positions show moderate variation in chemical composition of the clay with depth. The small variations in the chemical compositions of upslope soils on the Nam Phong catena are due to different degrees of weathering of the same parent rock, whereas soil on the toeslope position has a quite different elemental composition, possibly due to a different parent rock and the authigenesis of minerals in this landscape position where leached ions accumulate.
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Molina-Guzmán, Licet Paola, Paula Andrea Henao-Jaramillo, Lina Andrea Gutiérrez-Builes, and Leonardo Alberto Ríos-Osorio. "Microorganisms in Soils of Bovine Production Systems in Tropical Lowlands and Tropical Highlands in the Department of Antioquia, Colombia." International Journal of Agronomy 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/5379047.
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Studies on the physical and chemical effects of extensive grazing on soils have been performed in Colombia, but the effects of dairy cattle rearing on the biological properties of soils are not well known. The objective of this study was to evaluate microorganisms in 48 soils from livestock farms in the highland and lowland tropics in the Northern and Magdalena Medio subregions of the Department of Antioquia (Colombia). Principal component analysis demonstrated differences in the edaphic compositions of the soils, with increased percentages of root colonization by arbuscular mycorrhizal fungi and the density of microorganisms in farms that have soils with moderate phosphorus and nitrogen contents, low potassium content, and a moderately acidic pH. Agglomerative cluster analysis showed two groups for the highland tropic soils and six groups for the lowland tropic soils based on their population densities and interactions with the studied parameters. These results represent a first attempt to describe the density of microorganisms and the effect of soil physicochemical parameters on colonization by arbuscular mycorrhizal fungi in areas with determinant agroecological conditions, microbial functional diversity, and the presence of mycorrhizal fungi in livestock farm soils in Colombia.
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Camapum de Carvalho, José, and Gilson Gitirana. "Unsaturated soils in the context of tropical soils." Soils and Rocks 44, no. 3 (September 23, 2021): 1–25. http://dx.doi.org/10.28927/sr.2021.068121.
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The practice of geotechnical engineering in tropical climate regions must consider the use of unsaturated soil concepts. However, these concepts must also take into account the specific behavior traits of tropical soils, particularly those related to soil aggregation, pore structure, and mineralogy. This paper will initially present considerations on the typical properties of unsaturated tropical soils as well as fundamental concepts. Throughout the article, several engineering problems will be presented alongside reflections on the complex interaction between the numerous variables involved in the modeling and engineering practice of tropical unsaturated soil behavior. The paper addresses issues related to soil formation, chemical and mineral composition, physical properties, tropical soil classification, and structural characteristics of soils. Issues related to compaction and the influence of weathering, geomorphology and bioengineering are also addressed.
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Buessecker, Steffen, Kaitlyn Tylor, Joshua Nye, Keith E. Holbert, Jose D. Urquiza Muñoz, Jennifer B. Glass, Hilairy E. Hartnett, and Hinsby Cadillo-Quiroz. "Effects of sterilization techniques on chemodenitrification and N<sub>2</sub>O production in tropical peat soil microcosms." Biogeosciences 16, no. 23 (December 5, 2019): 4601–12. http://dx.doi.org/10.5194/bg-16-4601-2019.
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Abstract. Chemodenitrification – the non-enzymatic process of nitrite reduction – may be an important sink for fixed nitrogen in tropical peatlands. Rates and products of chemodenitrification are dependent on O2, pH, Fe2+ concentration, and organic matter composition, which are variable across peat soils. Assessing abiotic reaction pathways is difficult because sterilization and inhibition agents can alter the availability of reactants by changing iron speciation and organic matter composition. We compared six commonly used soil sterilization techniques – γ irradiation, chloroform, autoclaving, and the use of three different chemical inhibitors (mercury, zinc, and azide) – for their compatibility with chemodenitrification assays for tropical peatland soils (organic-rich, low-pH soil from the eastern Amazon). Out of the six techniques, γ irradiation resulted in soil treatments with the lowest cell viability and denitrification activity and the least effect on pH, iron speciation, and organic matter composition. Nitrite depletion rates in γ-irradiated soils were highly similar to untreated (live) soils, whereas other sterilization techniques showed deviations. Chemodenitrification was a dominant process of nitrite consumption in tropical peatland soils assayed in this study. Nitrous oxide (N2O) is one possible product of chemodenitrification reactions. Abiotic N2O production was low to moderate (3 %–16 % of converted nitrite), and different sterilization techniques lead to significant variations on production rates due to inherent processes or potential artifacts. Our work represents the first methodological basis for testing the abiotic denitrification and N2O production potential in tropical peatland soil.
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Ribeiro, Bruno Teixeira, Sérgio Henrique Godinho Silva, Elen Alvarenga Silva, and Luiz Roberto Guimarães Guilherme. "Portable X-ray fluorescence (pXRF) applications in tropical Soil Science." Ciência e Agrotecnologia 41, no. 3 (June 2017): 245–54. http://dx.doi.org/10.1590/1413-70542017413000117.
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ABSTRACT The X-ray fluorescence (XRF) is an analytical technique for determination of elemental composition of different materials. In soils, the XRF has many pedological, environmental and agronomic applications, mainly after the emergence of portable equipments (pXRF). This technique has been recently adopted and successfully used for soil characterization worldwide, but very rare works have been carried out in soils of developing countries. The soil characterization includes the complete elemental composition determination (nutrients, trace and rare-earth elements) and allows estimating some soil physical and chemical properties. In Brazil, this technique is still incipient, mainly the use of pXRF, however, it can greatly contribute to soil characterization in-field or in-lab conditions and also replacing methods of soil analyses considered non-environmentally friendly. This review summarizes the XRF technique including principles and the main applications of pXRF in soils highlighting its potential for tropical Soil Science.
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Gaiser, Thomas, Frieder Graef, and José Carvalho Cordeiro. "Water retention characteristics of soils with contrasting clay mineral composition in semi-arid tropical regions." Soil Research 38, no. 3 (2000): 523. http://dx.doi.org/10.1071/sr99001.
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In semi-arid tropical regions, the availability of reliable data for water retention in relation to soil type, texture, and organic matter content is low. It would be therefore desirable to develop pedotransfer functions (PTF) in order to estimate water retention characteristics from easily available soil parameters. In the present study, a soil database containing water retention characteristics, particle size distribution, and total organic carbon content of 663 horizons from semi-arid regions in NE Brazil and SE Niger was used to investigate the effect of contrasting clay mineral composition on water retention and PTF characteristics for soils from semi-arid tropical regions. For soil water content at field capacity (–33 kPa) and wilting point (–1500 kPa), PTFs were established and validated with disturbed samples from LAC soils (soils containing predominantly low activity clay; CEC < 24 cmol/kg clay) and non-LAC soils. The PTFs for the LAC soil group differed considerably from the PTFs for non-LAC soils with respect to the contribution of total organic carbon and silt content to the prediction of soil water content at field capacity and wilting point. For the particle size classes sand, loamy sand, sandy loam, and sandy clay loam, the mean measured soil water contents in LAC soils were significantly smaller than in non-LAC soils at a matric potential of –33 kPa. The results demonstrate the influence of clay mineral composition on soil water retention and its importance for the development of pedotransfer functions.
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Pett-Ridge, J., and M. K. Firestone. "Redox Fluctuation Structures Microbial Communities in a Wet Tropical Soil." Applied and Environmental Microbiology 71, no. 11 (November 2005): 6998–7007. http://dx.doi.org/10.1128/aem.71.11.6998-7007.2005.
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ABSTRACT Frequent high-amplitude redox fluctuation may be a strong selective force on the phylogenetic and physiological composition of soil bacterial communities and may promote metabolic plasticity or redox tolerance mechanisms. To determine effects of fluctuating oxygen regimens, we incubated tropical soils under four treatments: aerobic, anaerobic, 12-h oxic/anoxic fluctuation, and 4-day oxic/anoxic fluctuation. Changes in soil bacterial community structure and diversity were monitored with terminal restriction fragment length polymorphism (T-RFLP) fingerprints. These profiles were correlated with gross N cycling rates, and a Web-based phylogenetic assignment tool was used to infer putative community composition from multiple fragment patterns. T-RFLP ordinations indicated that bacterial communities from 4-day oxic/anoxic incubations were most similar to field communities, whereas those incubated under consistently aerobic or anaerobic regimens developed distinctly different molecular profiles. Terminal fragments found in field soils persisted either in 4-day fluctuation/aerobic conditions or in anaerobic/12-h treatments but rarely in both. Only 3 of 179 total fragments were ubiquitous in all soils. Soil bacterial communities inferred from in silico phylogenetic assignment appeared to be dominated by Actinobacteria (especially Micrococcus and Streptomycetes), “Bacilli,” “Clostridia,” and Burkholderia and lost significant diversity under consistently or frequently anoxic incubations. Community patterns correlated well with redox-sensitive processes such as nitrification, dissimilatory nitrate reduction to ammonium (DNRA), and denitrification but did not predict patterns of more general functions such as N mineralization and consumption. The results suggest that this soil's indigenous bacteria are highly adapted to fluctuating redox regimens and generally possess physiological tolerance mechanisms which allow them to withstand unfavorable redox periods.
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Gargallo-Garriga, Albert, Jordi Sardans, Abdulwahed Fahad Alrefaei, Karel Klem, Lucia Fuchslueger, Irene Ramírez-Rojas, Julian Donald, et al. "Tree Species and Epiphyte Taxa Determine the “Metabolomic niche” of Canopy Suspended Soils in a Species-Rich Lowland Tropical Rainforest." Metabolites 11, no. 11 (October 21, 2021): 718. http://dx.doi.org/10.3390/metabo11110718.
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Tropical forests are biodiversity hotspots, but it is not well understood how this diversity is structured and maintained. One hypothesis rests on the generation of a range of metabolic niches, with varied composition, supporting a high species diversity. Characterizing soil metabolomes can reveal fine-scale differences in composition and potentially help explain variation across these habitats. In particular, little is known about canopy soils, which are unique habitats that are likely to be sources of additional biodiversity and biogeochemical cycling in tropical forests. We studied the effects of diverse tree species and epiphytes on soil metabolomic profiles of forest floor and canopy suspended soils in a French Guianese rainforest. We found that the metabolomic profiles of canopy suspended soils were distinct from those of forest floor soils, differing between epiphyte-associated and non-epiphyte suspended soils, and the metabolomic profiles of suspended soils varied with host tree species, regardless of association with epiphyte. Thus, tree species is a key driver of rainforest suspended soil metabolomics. We found greater abundance of metabolites in suspended soils, particularly in groups associated with plants, such as phenolic compounds, and with metabolic pathways related to amino acids, nucleotides, and energy metabolism, due to the greater relative proportion of tree and epiphyte organic material derived from litter and root exudates, indicating a strong legacy of parent biological material. Our study provides evidence for the role of tree and epiphyte species in canopy soil metabolomic composition and in maintaining the high levels of soil metabolome diversity in this tropical rainforest. It is likely that a wide array of canopy microsite-level environmental conditions, which reflect interactions between trees and epiphytes, increase the microscale diversity in suspended soil metabolomes.
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Eskov, Alen K., Alexei O. Zverev, and Evgeny V. Abakumov. "Microbiomes in Suspended Soils of Vascular Epiphytes Differ from Terrestrial Soil Microbiomes and from Each Other." Microorganisms 9, no. 5 (May 11, 2021): 1033. http://dx.doi.org/10.3390/microorganisms9051033.
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Microbial biodiversity parameters for tropical rainforests remain poorly understood. Whilst the soil microbiome accounts up to 95% of the total diversity of microorganisms in terrestrial ecosystems, the microbiome of suspended soils formed by vascular epiphytes remains completely unexplored. Samples of ground and suspended soils were collected in Cat Tien National Park, southern Vietnam. DNA extraction and sequencing were performed, and libraries of 16s rDNA gene sequences were analyzed. Alpha diversity indices of the microorganisms were the highest in the forest ground soil. In general, the microbiological diversity of all the soil types was found to be similar at the phylum level. Taxonomic composition of the bacterial communities in the suspended soils of plants from the same species are not closer than the taxonomic compositions of the communities in the suspended soils of different plant species. However, the beta diversity analysis revealed significant differences in the movement of mineral elements in terrestrial versus suspended soils. Our data showed that the suspended soils associated with vascular epiphytes were a depository of unique microbiological biodiversity. A contributing factor was the presence of large amounts of organic matter in the suspended soils—deposits collected by the epiphytes—which would have been degraded by termites if it had reached the ground. Further, the nutrient content of the suspended soils was prime for soil respiration activity and taxonomic microbial community biodiversity.
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Samburova, Margarita Aleksandrovna, Tatyana Sergeevna Ermilova, Emil Aflatun ogly Salimzade, Olga Vladislavovna Kasharnaya, and Olga Vladislavovna Kasharnaya. "Relationship of soil cover mineral composition and cattle health." Agrarian Scientific Journal, no. 9 (September 25, 2022): 76–80. http://dx.doi.org/10.28983/asj.y2022i9pp76-80.
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The leading pathway for the supply of mineral elements to animals is the trophic chain "soil-plant-animal". The review article reveals the significance of the levels of macro and trace elements in soils of agricultural territories for the health and productivity of cattle, as well as some measures for normalization of the soils mineral composition and the mineral status of animals, the effectiveness of which is confirmed by scientific research.
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Ross, Sheila M. "Organic matter in tropical soils: current conditions, concerns and prospects for conservation." Progress in Physical Geography: Earth and Environment 17, no. 3 (September 1993): 265–305. http://dx.doi.org/10.1177/030913339301700301.
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Soil organic matter (SOM) plays a central role in maintaining tropical soil fertility. Its conservation and maintenance in tropical cultivation systems is imperative if soil degradation is to be halted and cropping made sustainable. Around 22-23% of global carbon is present in tropical ecosystems but only 2-3% of this is present in the soil. Fluxes of CO2 to the atmosphere from tropical soils after deforestation contributes to the greenhouse effect and could represent a 1-4% increase in the overall steady-state annual CO2 release to the atmosphere. The composition of SOM is extremely diverse, with active, or labile, fractions decomposing in a matter of months while the more resistant, or nonlabile, fractions remain in soil for many years. SOM plays a central role in providing good soil structure, in supplying nutrients and in providing ion exchange capacity in tropical soils. Organic matter decomposition rates in tropical soils are generally faster than in temperate soils because decay of the nonlabile fraction is generally faster. Changes in tropical land use have profound effects on SOM status. Tropical deforestation causes significant losses of soil carbon and nitrogen which tend to decline further under continuous cultivation. Reasons for declines in soil fertility include accelerated soil erosion, loss of litter influx after canopy removal and enhanced decomposition and nutrient mineralization rates after forest clearance. A wide range of soil management techniques have been designed to conserve and improve SOM stocks in tropical cultivation systems. These include agroforestry techniques, intercropping with legumes and the use of mulches and other organic inputs. While many of these techniques look promising in terms of improved crop yields, there is urgent need for research on how these practices alter the physical, chemical and biological processes and conditions of tropical soils.
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Nacro, Hassan Bismarck, Marie Christine Larré-Larrouy, Christian Feller, and Luc Abbadie. "Hydrolysable carbohydrate in tropical soils under adjacent forest and savanna vegetation in Lamto, Côte d'Ivoire." Soil Research 43, no. 6 (2005): 705. http://dx.doi.org/10.1071/sr03134.
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Carbohydrates represent 5–25% of the organic matter in soils. They constrain microbial activities and mineral nutrient production in soil and also reflect the whole microorganism community dynamic. The objective of this study was to determine the contents and composition of hydrolysable carbohydrates in soils collected in a forest–savanna mosaic landscape in the region of Lamto (Côte d’Ivoire). Capillary gas chromatography was used to identify and determine carbohydrates in soil profile under 4 tropical ecosystems: gallery and plateau forests, and grass and shrub tree savannas. Forest soils were higher in organic matter than savanna soils (0.50–2.96% C v. 0.53–1.22% C). The carbohydrate-C content of soils, expressed as percentage of total soil organic C, was low, a likely consequence of the tropical climate that promotes a rapid decomposition of surface plant debris. The carbohydrate-C content was higher under savanna soils (5–7%) than under forest soils (3–4%). Glucose, ribose, mannose, xylose, and galactose were the 5 most abundant extractable monosaccharides in all soils. Between them, only xylose and ribose are controlled by the vegetation type. The [(galactose + mannose) : (arabinose + xylose)] and [mannose : xylose] ratios suggested that most soil sugars derive from microbial biomass. The large abundance of microbial carbohydrates indicates intense microbial activities in the soil, and then rapid decomposition of soil organic matter favoured by the long wet season, with high temperatures and soil water availability at the site study. Results suggest clearly that the climate likely controls the amount and composition of carbohydrates in Lamto soils.
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Lopes, Bruna C., Raíssa S. Figueiredo, Juliana C. Araújo, and Antonio T. Matos. "Bacterial community dynamics in tropical soil after sewage sludge amendment." Water Science and Technology 82, no. 12 (November 3, 2020): 2937–47. http://dx.doi.org/10.2166/wst.2020.523.
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Abstract Although the widespread use of sewage sludge in developing countries is common, little is known about how sludge disposal can affect the microbial composition and diversity of tropical soils. We evaluated the effects of the sewage sludges of two types of anaerobic digestors differing, by the biological treatment they have undergone (uplow anaerobic sludge blanket and activated sludge digester), and two different disposal methods (surface and incorporated) on tropical soils. Samples were taken from topsoil (0–10 cm) and analyzed by amplifying the 16S rRNA genes to study the microbial community, and physicochemical analysis was performed concomitantly. The results indicated that, in general, sewage sludge amendment (SSA) significantly changed the tropical soil bacterial community by the sludge type and by application method. Moreover, the redundancy analysis diagram indicates that changes in soil chemical parameters over time due to SSA resulted in changes in the bacterial community's composition, increasing the population responsible for recycling nutrients in the soil.
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Abakumov, E. V., O. A. Rodina, and A. K. Eskov. "Humification and Humic Acid Composition of Suspended Soil in Oligotrophous Environments in South Vietnam." Applied and Environmental Soil Science 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/1026237.
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Humification is considered to be a global process that is implemented in soils and organic sediments and also in natural water and air. The term “suspended soils” has become increasingly common in recent years. Suspended soils are defined as the part of the organic matter that has not undergone the full decomposition process and has not turned into the humus of terrestrial soils. Suspended soils were shown to contain higher total nitrogen, phosphorus, and potassium contents than the forest soil, but the moisture content in suspended soils was significantly lower. Our study of the structural composition of humic substances in suspended soils was conducted with an aim of evaluating the humification rates and structural composition of humic acids in the suspended soil in tropical forests of South Vietnam. Soil samples from three selected areas were investigated: the soil under phorophytes (mineral soil presented by samples of topsoil of the typical dry savanna landscape) and two soils from epiphytous formations. Samples were collected from savanna-type sparse communities, located on oligotrophous plains in Phú Quốc Island (South Vietnam) in 2015. General properties of the soil and the elemental composition of suspended soils were determined, and the humic substance chemical composition was evaluated using solid state 13C-NMR. Data obtained showed that the pH of the soils under phorophytes was higher than in the suspended soils; basal respiration did not tend to change indices between soils under phorophytes and suspended soils, but the suspended soil was less enriched by nitrogen than the soil under phorophytes. This can be related to the total amount of organic matter exposed to humification in various soils and to the presence of an essential portion of mineral particles in the soil under phorophytes. Data on elemental composition of the humic acids (HAs) indicated that one method of humification is implemented in all three soils that were investigated. The humic acids of the phorophyte soil showed the same content of aromatic fraction as the suspended soil. The most comparable soil type in terms of humic substance composition is Cambisols from humid forests of subboreal and subtropical zones. The humification process implemented in suspended soils showed the absence of mineral compounds or mineral fine earth, which indicated that humification in conditions of pure organic substrates can result in formation of deep humified organic matter, as shown by humic acids with an essential aromatic fraction content.
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Paoletti, Maurizio G., R. A. J. Taylor, Benjamin R. Stinner, Deborah H. Stinner, and David H. Benzing. "Diversity of soil fauna in the canopy and forest floor of a Venezuelan cloud forest." Journal of Tropical Ecology 7, no. 3 (August 1991): 373–83. http://dx.doi.org/10.1017/s0266467400005654.
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ABSTRACTArboreal and terresterial soil and lilter were sampled for macro-and microinvertebrates at two locations in a Venezuelan cloud forest. Fauna were most abundant in forest floor soil and associated litter. However, media suspended in the canopy and particularly those trapped in bromeliad shoots were most densely populated, while the diversities of the arboreal and terrestrial soil fauna were indistinguishable. Rates of leaf litter decomposition in the arboreal and terrestrial soils were similar, but the arboreal soils contained higher concentrations of mineral nutrients and carbon. Implications of these findings for the definition of soil in humid tropical forests, and related differences between temperate and tropical forests are discussed. The similarities in diversity and differences in species composition between arboreal and terrestrial soil fauna raise questions concerning the evolution of tropical soil fauna, as well as the estimate of global biotic diversity.
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Echeverría-Beirute, Fabián, Ingrid Varela-Benavides, Jose P Jiménez-Madrigal, Milagro Carvajal-Chacon, and Tomás Guzmán-Hernández. "eDNA extraction protocol for metagenomic studies in tropical soils." BioTechniques 71, no. 6 (December 2021): 580–86. http://dx.doi.org/10.2144/btn-2021-0057.
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The lack of knowledge about biological communities residing in soils, especially those in tropical regions, represents a constraint to management practices to take advantage of the ecological services provided by soil microbiota to agroecosystems. One of the complexities derived from describing biological diversity in such tropical conditions comes from the methods used to isolate microorganisms without altering the composition of the sample. The goal of this study was to establish a protocol for adequate soil sampling and environmental DNA extraction from a tropical region in Costa Rica. We present an up-to-date protocol optimized for tropical soils which improves sevenfold the amount of DNA extracted without significantly affecting the 260/280 and 260/230 ratios compared with commercially available kits and standard protocols.
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Gao, Dandan, Faming Wang, Jian Li, Shiqin Yu, Zhian Li, and Jie Zhao. "Soil nematode communities as indicators of soil health in different land use types in tropical area." Nematology 22, no. 6 (July 14, 2020): 595–610. http://dx.doi.org/10.1163/15685411-00003325.
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Summary The study of soil nematode communities is a powerful tool that has been widely used as an indicator of soil health. This study explored whether soil nematode composition of different land use types could be used as a baseline to indicate the soil health of both natural and anthropogenic ecosystems. The soil nematode community compositions were documented for five land use types in tropical China: bare land, secondary forest, old forest, eucalyptus plantation and litchi orchards. The first three land use types are natural ecosystems and considered as a vegetation succession, whereas the other two are anthropogenically managed ecosystems. The vegetation succession from bare land to secondary and old forests increased soil nematode abundance, diversity, diversity-weighted abundance and complexity of community structure. During the wet season, the abundances of the total nematodes, bacterivores, fungivores and herbivores were significantly lower in eucalyptus plantation and litchi orchards than in secondary and old forests, but higher than in bare land. During the dry season, the abundances of the total nematodes and each trophic group were greatest in orchards. The pattern of the diversity-weighted abundance of each nematode trophic group was similar to that of nematode trophic group abundance. The results indicate that soil nematode communities of different land use types could be used for comparison of soil health conditions in natural and managed ecosystems. Particularly, the soil health conditions as indicated through nematode communities of the two managed ecosystems were not as good as those of secondary and old forests, whereas litchi orchards might have better soil health conditions than eucalyptus plantations in tropical China.
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Mueller-Niggemann, C., S. R. Utami, A. Marxen, K. Mangelsdorf, T. Bauersachs, and L. Schwark. "Distribution of tetraether lipids in agricultural soils – differentiation between paddy and upland management." Biogeosciences Discussions 12, no. 20 (October 19, 2015): 16709–54. http://dx.doi.org/10.5194/bgd-12-16709-2015.
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Abstract. Insufficient knowledge of the composition and variation of isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) in agricultural soils exists, despite of the potential effect of different management types (e.g. soil/water and redox conditions, cultivated plants) on GDGT distribution. Here, we determined the influence of different soil management types on the GDGT composition in paddy (flooded) and adjacent upland (non-flooded) soils, and if available also forest, bushland and marsh soils. To compare the local effects on GDGT distribution patterns, we collected comparable soil samples in various locations from tropical (Indonesia, Vietnam and Philippines) and subtropical (China and Italy) sites. We found that differences in the distribution of isoprenoid GDGTs (iGDGTs) as well as of branched GDGTs (brGDGTs) are predominantly controlled by management type and only secondarily by climatic exposition. In general upland soil had higher crenarchaeol contents than paddy soil, which on the contrary was more enriched in GDGT-0. The GDGT-0 / crenarchaeol ratio was 3–27 times higher in paddy soil and indicates the enhanced presence of methanogenic archaea, which were additionally linked to the number of rice cultivation cycles per year (higher number of cycles was coupled with an increase in the ratio). The TEX86 values were 1.3 times higher in upland, bushland and forest soils than in paddy soils. In all soils brGDGT predominated over iGDGTs, with the relative abundance of brGDGTs increasing from subtropical to tropical soils. Higher BIT values in paddy soils compared to upland soils together with higher BIT values in soil from subtropical climates indicate effects on the amounts of brGDGT through differences in management as well as climatic zones. In acidic soil CBT values correlated well with soil pH. In neutral to alkaline soils, however, no apparent correlation but an offset between paddy and upland managed soils was detected, which may suggest that soil moisture may exert an additional control on the CBT in these soils. Lower MBT' values and calculated temperatures (TMC) in paddy soils compared to upland soils may indicate a management (e.g. enhanced soil moisture through flooding practises) induced effect on mean annual soil temperature (MST).
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Hikmatullah, Hikmatullah, and Kesumo Nugroho. "Tropical Volcanic Soils From Flores Island, Indonesia." JOURNAL OF TROPICAL SOILS 15, no. 1 (April 9, 2018): 83. http://dx.doi.org/10.5400/jts.2010.v15i1.83-93.
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Tropical Volcanic Soils from Flores Island, Indonesia (Hikmatullah and K Nugroho): Soils that are developed in tropical region with volcanic parent materials have many unique properties, and high potential for agricultural use. The purpose of this study is to characterize the soils developed on volcanic materials from Flores Island, Indonesia, and to examine if the soils meet the requirements for andic soil properties. Selected five soils profiles developed from andesitic volcanic materials from Flores Island were studied to determine their properties. They were compared in their physical, chemical and mineralogical characteristics according to their parent material, and climatic characteristic different. The soils were developed under humid tropical climate with ustic to udic soil moisture regimes with different annual rainfall. The soils developed from volcanic ash parent materials in Flores Island showed different properties compared to the soils derived from volcanic tuff, even though they were developed from th e same intermediary volcanic materials. The silica contents, clay mineralogy and sand fractions, were shown as the differences. The different in climatic conditions developed similar properties such as deep solum, dark color, medium texture, and very friable soil consistency. The soils have high organic materials, slightly acid to acid, low to medium cation exchange capacity (CEC). The soils in western region have higher clay content and showing more developed than of the eastern region. All the profiles meet the requirements for andic soil properties, and classified as Andisols order. The composition of sand mineral was dominated by hornblende, augite, and hypersthenes with high weatherable mineral reserves, while the clay fraction was dominated by disordered kaolinite, and hydrated halloysite. The soils were classified into subgroup as Thaptic Hapludands, Typic Hapludands, and Dystric Haplustands.
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Högberg, Peter. "Soil nutrient availability, root symbioses and tree species composition in tropical Africa: a review." Journal of Tropical Ecology 2, no. 4 (November 1986): 359–72. http://dx.doi.org/10.1017/s0266467400000997.
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ABSTRACTRelations between soil nutrient availability, the occurrence of root symbioses and tree species composition in tropical Africa are discussed in the light of new evidence. Transects from humid areas at the equator towards the deserts can be summarized as follows:High availability of nitrogen, low availability of phosphorus, low pH and aluminium toxicity probably restrict the competitiveness of nitrogen-fixing species in the forests on highly weathered and leached soils in humid west and central Africa. Ectomycorrhizal species attain dominance in species-poor forests on the soils poorest in phosphorus, while species with vesicular-arbuscular (VA) mycorrhiza form diverse forests on more fertile soils. Nitrogen-fixing species, which mostly are VA mycorrhizal, are more common in woodlands, where nitrogen is lost in grass fires, than in forests, which have a more closed nitrogen cycle. Low availability of phosphorus, however, limits the growth of nitrogen-fixing species in moist savannas. Ectomycorrhizal species are dominant, possibly because of a competitive advantage conferred by the large storage capacity of the fungal mantles under conditions of discontinuous nutrient supply. Nitrogen-fixing species become more abundant towards drier areas with an increase in soil phosphorus and a decline in soil nitrogen. These conditions culminate at the desert fringe, where nitrogen-fixing species reach their most conspicuous development.It is concluded that soil nutrient availability and root symbioses interact and strongly affect the composition of vegetation communities.
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Hamanaka, Akihiro, Takashi Sasaoka, Hideki Shimada, and Shinji Matsumoto. "Experimental study on soil erosion under different soil composition using rainfall simulator." Plant, Soil and Environment 65, No. 4 (April 23, 2019): 181–88. http://dx.doi.org/10.17221/68/2019-pse.
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Soil erosion is one of the major environmental problems in open-cut mines in tropical regions. It causes negative impacts including the removal of nutrient-rich topsoil, destroys aquatic habitat, dam and pond siltation, clogs river by deposition of sediment, and causes water pollution in the rehabilitation process. Soil texture is an important factor to affect soil erosion. In this study, artificial rainfall experiment in the laboratory scale was conducted to clarify the mechanism of soil erosion under the different soil composition and to discuss the methods for minimizing soil erosion. The obtained results showed that the soil seal generated due to the presence of fine particle under high rainfall intensity is the main contributor to accelerate the soil erosion. Additionally, the surface coverage by the cover crops is the most effective measure to reduce soil erosion because both the coarse and fine contents runoff can be minimized while arranging of the slope angle is effective for reducing the runoff of coarse contents and the soil compaction is effective to reduce that of fine contents. Soil erosion can be minimized by selecting prevention method considering the type of soil because the prevention effect on soil erosion is different depending on the type of soil.
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Oluwatoyin, O. Akinola, Olusola, and A. Ola Olorun. "Dispersion of Trace Elements as Consequence of insitu Weathering in granite-derived Tropical Soils in Southwestern Nigeria." International Journal of Research and Innovation in Applied Science 07, no. 10 (2022): 87–93. http://dx.doi.org/10.51584/ijrias.2022.71008.
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Trace elements composition of granite and tropical soils formed by in-situ weathering over the basement complex of Ikere-Ekiti, Ado-Ekiti and Igbrara-Odo areas of SW Nigeria is evaluated and reported. The granitoids exhibit chemical features such as is common to other granite bodies across the basement areas. The soil profiles typically have four different horizons with contrasting physical characteristics. Analytical result from ICP-MS technique revealed compositional variation along vertical direction within depth of the profiles. Trace element as average for the granite reveals low Tm (0.5 ppm), Eu (2.1 ppm), Co (5.1 ppm), Sc (7.2 ppm), Hf (7.6 ppm), Sm (12.6 ppm), and Th (30.5 ppm) values, while La (110 ppm), Ce (216 ppm), Cr (235.5 ppm), and Ba (963 ppm) show enrichments. All the soils have Sm, Eu, Th, Hf and Co contents below 10 ppm; Sc, La and Ce values fall between 10-100 ppm, while Cr and Ba contents fall between 200-1500 ppm. Variation between trace contents in granite and the derived soils as revealed along depths of the profile indicates greater mobility of Th, Sc and Ba during chemical weathering while Eu and Tm are least mobile. Pronounced compositional variation occur at relatively shallow (0-1m) depth in near surface area all the profiles.
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Sylvain, Zachary A., David H. Branson, Tatyana A. Rand, Natalie M. West, and Erin K. Espeland. "Decoupled recovery of ecological communities after reclamation." PeerJ 7 (June 21, 2019): e7038. http://dx.doi.org/10.7717/peerj.7038.
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Grassland restoration is largely focused on creating plant communities that match reference conditions. However, these communities reflect only a subset of the biodiversity of grassland systems. We conducted a multi-trophic study to assess ecosystem recovery following energy development for oil and gas extraction in northern US Great Plains rangelands. We compared soil factors, plant species composition and cover, and nematode trophic structuring between reclaimed oil and gas well sites (“reclaims”) that comprise a chronosequence of two—33 years since reclamation and adjacent, undeveloped rangeland at distances of 50 m and 150 m from reclaim edges. Soils and plant communities in reclaims did not match those on undeveloped rangeland even after 33 years. Reclaimed soils had higher salt concentrations and pH than undeveloped soils. Reclaims had lower overall plant cover, a greater proportion of exotic and ruderal plant cover and lower native plant species richness than undeveloped rangeland. However, nematode communities appear to have recovered following reclamation. Although total and omni-carnivorous nematode abundances differed between reclaimed well sites and undeveloped rangeland, community composition and structure did not. These findings suggest that current reclamation practices recover the functional composition of nematode communities, but not soil conditions or plant communities. Our results show that plant communities have failed to recover through reclamation: high soil salinity may create a persistent impediment to native plant growth and ecosystem recovery.
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Higgins, M. A., G. P. Asner, E. Perez, N. Elespuru, and A. Alonso. "Variation in photosynthetic and nonphotosynthetic vegetation along edaphic and compositional gradients in northwestern Amazonia." Biogeosciences 11, no. 13 (July 3, 2014): 3505–13. http://dx.doi.org/10.5194/bg-11-3505-2014.
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Abstract. Tropical forests vary substantially in aboveground properties such as canopy height, canopy structure, and plant species composition, corresponding to underlying variations in soils and geology. Forest properties are often difficult to detect and map in the field, however, due to the remoteness and inaccessibility of these forests. Spectral mixture analysis of Landsat imagery allows mapping of photosynthetic and nonphotosynthetic vegetation quantities (PV and NPV), corresponding to biophysical properties such as canopy openness, forest productivity, and disturbance. Spectral unmixing has been used for applications ranging from deforestation monitoring to identifying burn scars from past fires, but little is known about variations in PV and NPV in intact rainforests. Here we use spectral unmixing of Landsat imagery to map PV and NPV in northern Amazonia, and to test their relationship to soils and plant species composition. To do this we sampled 117 sites crossing a geological boundary in northwestern Amazonia for soil cation concentrations and plant species composition. We then used the Carnegie Landsat Analysis System to map PV and NPV for these sites from multiple dates of Landsat imagery. We found that soil cation concentrations and plant species composition consistently explain a majority of the variation in remotely sensed PV and NPV values. After combining PV and NPV into a single variable (PV–NPV), we determined that the influence of soil properties on canopy properties was inseparable from the influence of plant species composition. In all cases, patterns in PV and NPV corresponded to underlying geological patterns. Our findings suggest that geology and soils regulate canopy PV and NPV values in intact tropical forests, possibly through changes in plant species composition.
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Higgins, M. A., G. P. Asner, E. Perez, N. Elespuru, and A. Alonso. "Variation in photosynthetic and nonphotosynthetic vegetation along edaphic and compositional gradients in northwestern Amazonia." Biogeosciences Discussions 11, no. 3 (March 3, 2014): 3535–57. http://dx.doi.org/10.5194/bgd-11-3535-2014.
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Abstract. Tropical forests vary substantially in aboveground properties such as canopy height, canopy structure, and plant species composition, corresponding to underlying variations in soils and geology. Forest properties are often difficult to detect and map in the field, however, due to the remoteness and inaccessibility of these forests. Spectral mixture analysis of Landsat imagery allows mapping of photosynthetic and nonphotosynthetic vegetation quantities (PV and NPV), corresponding to biophysical properties such as canopy openness, forest productivity, and disturbance. Spectral unmixing has been used for applications ranging from deforestation monitoring to identifying burn scars from past fires, but little is known about variations in PV and NPV in intact rainforest. Here we use spectral unmixing of Landsat imagery to map PV and NPV in northern Amazonia, and to test their relationship to soils and plant species composition. To do this we sampled 117 sites crossing a geological boundary in northwestern Amazonia for soil cation concentrations and plant species composition. We then used the Carnegie Landsat Analysis System to map PV and NPV for these sites from multiple dates of Landsat imagery. We found that soil cation concentrations and plant species composition consistently explain a majority of the variation in remotely sensed PV and NPV values. After combining PV and NPV into a single variable (PV-NPV), we determined that the influence of soil properties on canopy properties was inseparable from the influence of plant species composition. In all cases, patterns in PV and NPV corresponded to underlying geological patterns. Our findings suggest that geology and soils regulate canopy PV and NPV values in intact tropical forest, possibly through changes in plant species composition.
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Yuan, Jin-Hua, and Ren-Kou Xu. "Effects of biochars generated from crop residues on chemical properties of acid soils from tropical and subtropical China." Soil Research 50, no. 7 (2012): 570. http://dx.doi.org/10.1071/sr12118.
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The chemical compositions of biochars from ten crop residues generated at 350°C and their effects on chemical properties of acid soils from tropical and subtropical China were investigated. There was greater alkalinity and contents of base cations in the biochars from legume residues than from non-legume residues. Carbonates and organic anions of carboxyl and phenolic groups were the main forms of alkalis in the biochars, and their relative contributions to biochar alkalinity varied with crop residues. Incubation experiments indicated that biochar incorporation increased soil pH and soil exchangeable base cations and decreased soil exchangeable acidity. There were greater increases in soil pH and soil exchangeable base cations, and a greater decrease in soil exchangeable acidity, for biochars from legume than from non-legume residues. The biochars did not increase the cation exchange capacity (CEC) of soils with relatively high initial CEC but did increase the CEC of soils with relatively low initial CEC at an addition level of 1%. The incorporation of biochars from crop residues not only corrected soil acidity but also increased contents of potassium, magnesium, and calcium in these acid soils from tropical and subtropical regions and thus improved soil fertility.
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Busato, Jader Galba, Tairone Paiva Leão, Marihus Altoé Baldotto, and Luciano Pasqualoto Canellas. "Organic matter quality and dynamics in tropical soils amended with sugar industry residue." Revista Brasileira de Ciência do Solo 36, no. 4 (August 2012): 1179–88. http://dx.doi.org/10.1590/s0100-06832012000400012.
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Soil organic matter depletion caused by agricultural management systems have been identified as a critical problem in most tropical soils. The application of organic residues from agro-industrial activities can ameliorate this problem by increasing soil organic matter quality and quantity. Humic substances play an important role in soil conservation but the dynamics of their transformations is still poorly understood. This study evaluated the effect of compost application to two contrasting tropical soils (Inceptisol and Oxisol) for two years. Soil samples were incubated with compost consisting of sugarcane filter cake, a residue from the sugar industry, at 0, 40, 80, and 120 Mg ha-1. Filter cake compost changed the humic matter dynamics in both content and quality, affecting the soil mineralogical composition. It was observed that carbon mineralization was faster in the illite-containing Inceptisol, whereas humic acids were preserved for a longer period in the Oxisol. In both soils, compost application increased fulvic acid contents, favoring the formation of small hydrophilic molecules. A decrease in fluorescence intensity according to the incubation time was observed in the humic acids extracted from amended soils, revealing important chemical changes in this otherwise stable C pool.
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Knief, Claudia, Supika Vanitchung, Narumon W. Harvey, Ralf Conrad, Peter F. Dunfield, and Amnat Chidthaisong. "Diversity of Methanotrophic Bacteria in Tropical Upland Soils under Different Land Uses." Applied and Environmental Microbiology 71, no. 7 (July 2005): 3826–31. http://dx.doi.org/10.1128/aem.71.7.3826-3831.2005.
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ABSTRACT Three upland soils from Thailand, a natural forest, a 16-year-old reforested site, and an agricultural field, were studied with regard to methane uptake and the community composition of methanotrophic bacteria (MB). The methane uptake rates were similar to rates described previously for forest and farmland soils of the temperate zone. The rates were lower at the agricultural site than at the native forest and reforested sites. The sites also differed in the MB community composition, which was characterized by denaturing gradient gel electrophoresis (DGGE) of pmoA gene fragments (coding for a subunit of particulate methane monooxygenase) that were PCR amplified from total soil DNA extracts. Cluster analysis based on the DGGE banding patterns indicated that the MB communities at the forested and reforested sites were similar to each other but different from that at the farmland site. Sequence analysis of excised DGGE bands indicated that Methylobacter spp. and Methylocystis spp. were present. Sequences of the “forest soil cluster” or “upland soil cluster α,” which is postulated to represent organisms involved in atmospheric methane consumption in diverse soils, were detected only in samples from the native forest and reforested sites. Additional sequences that may represent uncultivated groups of MB in the Gammaproteobacteria were also detected.
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Dörr de Quadros, Patricia, Adam R. Martin, Kateryna Zhalnina, Raquel Dias, Adriana Giongo, Roberta Fulthorpe, Cimelio Bayer, Eric W. Triplett, and Flávio A. de O. Camargo. "Lablab Purpureus Influences Soil Fertility and Microbial Diversity in a Tropical Maize-Based No-Tillage System." Soil Systems 3, no. 3 (August 6, 2019): 50. http://dx.doi.org/10.3390/soilsystems3030050.
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There are multiple mechanisms by which enhanced diversity of plant communities improves soil structure and function. One critical pathway mediating this relationship is through changes to soil prokaryotic communities. Here, nine different cropping systems were studied to evaluate how legume and grass cover crops influence soil fertility and microbial communities in a maize-based no tillage system. The soil’s bacterial and archaeal communities were sequenced (Illumina GAIIx, 12 replicates for treatment) and correlated with eight different soil features. The microbial community composition differed widely between planting treatments, with three primary “community types” emerging in multivariate space: (1) A community type associated with bare soil linked with low P, low pH, and high aluminum [Al]; (2) a community type associated with Lablab beans linked with high soil N, total organic carbon and other base cation concentrations, and high pH; and (3) a community type of all other non-lablab planting arrangements linked with higher soil P (relative to bare soil), but lower soil fertility (N and base cations). Lablab-based arrangements also expressed the highest microbial richness and alpha diversity. The inclusion of Lablab in maize-based cropping systems represents a potential alternative to reduce the use of chemical fertilizers and increase the chemical and biological quality in agricultural soils under the no-tillage system.