scholarly journals Aluminous clay and pedogenic Fe oxides modulate aggregation and related carbon contents in soils of the humid tropics

2021 ◽  
Author(s):  
Maximilian Kirsten ◽  
Robert Mikutta ◽  
Didas N. Kimaro ◽  
Karl-Heinz Feger ◽  
Karsten Kalbitz
Keyword(s):  
Land Use ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Clay Content ◽  
Tropical Soils ◽  
Positive Feedbacks ◽  
Fe Oxides ◽  
Fe Content ◽  
Wide Range ◽  
High Level

Abstract. Aggregation affects a wide range of physical and biogeochemical soil properties with positive feedbacks on soil carbon storage. For weathered tropical soils, aluminous clays (kaolinite and gibbsite) and pedogenic Fe (oxyhydr)oxides (goethite and hematite; termed Fe oxides) have been suggested as important building units for aggregates. However, as both secondary aluminosilicates and Fe oxides are part of the clay-sized fraction it is hard to separate, how certain mineral phases modulate aggregation, and what consequences this has for organic carbon (OC) persistence after land-use change. We selected topsoils with unique mineralogical compositions in the East Usambara Mountains of Tanzania under forest and cropland. Soils are varying in contents of aluminous clay and Fe oxides. Across the mineralogical combinations, we determined the aggregate size distribution, aggregate stability, OC contents of aggregate size fractions as well as changes in aggregation and OC contents under forest and cropland land use. We found the soil aggregation patterns (high level of macroaggregation and aggregate stability) more similar than different among mineralogical combinations. Yet, an aluminous clay content > 250 g kg−1 in combination with pedogenic Fe contents  4 mm. In contrast, a pedogenic Fe content > 60 g kg−1 in combination with aluminous clay content of

scholarly journals Aluminous clay and pedogenic Fe oxides modulate aggregation and related carbon contents in soils of the humid tropics

SOIL ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 363-375
Author(s):  
Maximilian Kirsten ◽  
Robert Mikutta ◽  
Didas N. Kimaro ◽  
Karl-Heinz Feger ◽  
Karsten Kalbitz
Keyword(s):  
Land Use ◽  
Size Distribution ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Clay Content ◽  
Tropical Soils ◽  
Positive Effects ◽  
Fe Oxides ◽  
Aggregate Size Distribution ◽  
Wide Range

Abstract. Aggregation affects a wide range of physical and biogeochemical soil properties with positive effects on soil carbon storage. For weathered tropical soils, aluminous clays (kaolinite and gibbsite) and pedogenic Fe (oxyhydr)oxides (goethite and hematite; termed “Fe oxides”) have been suggested as important building units for aggregates. However, as aluminosilicates, aluminum hydroxides, and Fe oxides are part of the clay-sized fraction it is hard to separate how certain mineral phases modulate aggregation. In addition, it is not known what consequences this will have for organic carbon (OC) persistence after land-use change. We selected topsoils with unique mineralogical compositions in the East Usambara Mountains of Tanzania under forest and cropland land uses, varying in contents of aluminous clay and Fe oxides. Across the mineralogical combinations, we determined the aggregate size distribution, aggregate stability, OC contents of aggregate size fractions, and changes in aggregation and OC contents under forest and cropland land use. Patterns in soil aggregation were rather similar across the different mineralogical combinations (high level of macroaggregation and high aggregate stability). Nevertheless, we found some statistically significant effects of aluminous clay and pedogenic Fe oxides on aggregation and OC storage. An aluminous clay content > 250 g kg−1 in combination with pedogenic Fe contents < 60 g kg−1 significantly promoted the formation of large macroaggregates > 4 mm. In contrast, a pedogenic Fe content > 60 g kg−1 in combination with aluminous clay content of < 250 g kg−1 promoted OC storage and persistence even under agricultural use. The combination with low aluminous clay and high pedogenic Fe contents displayed the highest OC persistence, despite conversion of forest to cropland causing substantial disaggregation. This indicates that aggregation in these tropical soils is modulated by the mineralogical regime, causing moderate but significant differences in aggregate size distribution. Nevertheless, aggregation was little decisive for overall OC persistence in these highly weathered soils, where OC storage is more regulated by direct mineral–organic interactions.

scholarly journals Increase soil aggregate stability can limit colloidal phosphorus loss potentials from agricultural systems

2019 ◽  
Author(s):  
Fayong Li ◽  
Xinqiang Liang ◽  
Hua Li ◽  
Yingbin Jin ◽  
Junwei Jin ◽  
...  
Keyword(s):  
Land Use ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Paddy Soils ◽  
Total Carbon ◽  
Agricultural Systems ◽  
Soil Aggregate Stability ◽  
Soil P ◽  
Land Use Types

Abstract Background Colloid-facilitated phosphorus (P) transport is a recognized important pathway for soil P loss in agricultural systems, but limited information is available on the soil aggregate-associated colloidal P. To elucidate the effects of aggregate size on the loss potential of colloidal P (P coll ) in agricultural systems, soils (0-20 cm depth) from six land use types were sampled in Zhejiang province in the Yangtz river delta region, China. The aggregate size fractions (2–8 mm, 0.26–2 mm, 0.053–0.26 mm and <0.053 mm) separated by wet-sieving method were analyzed.Results Results showed that the 0.26–2 mm small macroaggregates had the highest total P (TP) content. For acidic soils, the highest P coll content was also found in the 0.26–2 mm aggregate size, while the lowest was found in the <0.053 mm (silt+clay)-sized particles, the opposite of that found in alkaline soils. Paddy soils contained less P coll than other land use types. The P coll in total dissolved P (TDP) was dominated by <0.053 mm (silt+clay)-sized particles. Aggregate size did strongly influence the loss potential of P coll in paddy soils, where P coll contributed up to 83% TDP in the silt+clay sized particles. The P coll content was positively correlated with TP, Al, Fe and mean weight diameter (MWD). Aggregate associated total carbon (TC), total nitrogen (TN), C/P, and C/N had significant, but negative effects on the contribution of P coll to potential soil P losses. The P coll content of the aggregates was controlled by aggregate associated TP and Al content as well as soil pH value, with P coll loss potential from aggregates being controlled by its organic matter content.Conclusion Therefore, we conclude that management practices that increase soil aggregate stability or its organic carbon content will limit P coll loss from agricultural systems.

Extremely Light Weight Rheocast Components for Automotive Space Frame

2012 ◽  
Vol 192-193 ◽  
pp. 545-550 ◽  
Author(s):  
Mario Rosso ◽  
Ildiko Peter ◽  
Gianluigi Chiarmetta ◽  
Ivano Gattelli
Keyword(s):  
High Performance ◽  
Mechanical Tests ◽  
Standard Samples ◽  
Fe Content ◽  
Wide Range ◽  
Automotive Parts ◽  
Fracture Surface Analysis ◽  
High Level ◽  
Non Destructive ◽  
Very High

This paper presents an analysis of a new rheocasting process suitable for the manufacturing of high performance automotive parts. The process is able for the realization of components using Al alloys. An important aspect is related to the possibility to obtain quite wide range of thicknesses, starting from 2.5 mm. The used alloy is the well known A356, with low Fe content, maximum 0.08 wt%. T6 heat treatments has been performed, while the soundness of the parts has been certified by non destructive tests. These parts are produced to be mounted on a top level and famous sport car. Non standard samples for mechanical tests have been machined directly from the components. Following the mechanical tests fracture surface analysis has been carried out by SEM to observe some morphological details and to evaluate the influence of the process and of the alloy conditions on the fracture behaviour. On the polished transverse sections of the samples morphological analysis has been performed. The obtained results shown high level of mechanical strength for all series of components. The reliability of the process is very high at a convenient level of manufacturing rate. The weldability of the parts has been demonstrated.

scholarly journals Organic matter cycling along geochemical, geomorphic, and disturbance gradients in forest and cropland of the African Tropics – project TropSOC database version 1.0

2021 ◽  
Vol 13 (8) ◽  
pp. 4133-4153
Author(s):  
Sebastian Doetterl ◽  
Rodrigue K. Asifiwe ◽  
Geert Baert ◽  
Fernando Bamba ◽  
Marijn Bauters ◽  
...  
Keyword(s):  
Land Use ◽  
Tropical Soils ◽  
Soil Microbial Activity ◽  
Biogeochemical Cycles ◽  
Congo Basin ◽  
Land Conversion ◽  
Soil Geochemistry ◽  
East African ◽  
Soil Microbial ◽  
Wide Range

Abstract. The African Tropics are hotspots of modern-day land use change and are, at the same time, of great relevance for the cycling of carbon (C) and nutrients between plants, soils, and the atmosphere. However, the consequences of land conversion on biogeochemical cycles are still largely unknown as they are not studied in a landscape context that defines the geomorphic, geochemical, and pedological framework in which biological processes take place. Thus, the response of tropical soils to disturbance by erosion and land conversion is one of the great uncertainties in assessing the carrying capacity of tropical landscapes to grow food for future generations and in predicting greenhouse gas fluxes from soils to the atmosphere and, hence, future earth system dynamics. Here we describe version 1.0 of an open-access database created as part of the project “Tropical soil organic carbon dynamics along erosional disturbance gradients in relation to variability in soil geochemistry and land use” (TropSOC). TropSOC v1.0 (Doetterl et al., 2021, https://doi.org/10.5880/fidgeo.2021.009) contains spatially and temporally explicit data on soil, vegetation, environmental properties, and land management collected from 136 pristine tropical forest and cropland plots between 2017 and 2020 as part of monitoring and sampling campaigns in the eastern Congo Basin and the East African Rift Valley system. The results of several laboratory experiments focusing on soil microbial activity, C cycling, and C stabilization in soils complement the dataset to deliver one of the first landscape-scale datasets to study the linkages and feedbacks between geology, geomorphology, and pedogenesis as controls on biogeochemical cycles in a variety of natural and managed systems in the African Tropics. The hierarchical and interdisciplinary structure of the TropSOC database allows linking of a wide range of parameters and observations on soil and vegetation dynamics along with other supporting information that may also be measured at one or more levels of the hierarchy. TropSOC's data mark a significant contribution to improve our understanding of the fate of biogeochemical cycles in dynamic and diverse tropical African (agro-)ecosystems. TropSOC v1.0 can be accessed through the Supplement provided as part of this paper or as a separate download via the websites of the Congo Biogeochemistry Observatory and GFZ Data Services where version updates to the database will be provided as the project develops.

scholarly journals Enhanced soil aggregate stability limits colloidal phosphorus loss potentials in agricultural systems

2020 ◽  
Author(s):  
Fayong Li ◽  
XINQIANG LIANG ◽  
Hua Li ◽  
Yingbin Jin ◽  
Junwei Jin ◽  
...  
Keyword(s):  
Land Use ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Paddy Soils ◽  
Agricultural Systems ◽  
Soil Aggregate Stability ◽  
Soil P ◽  
Land Use Types ◽  
Potential Loss

Abstract Background: Colloid-facilitated phosphorus (P) transport is recognized as an important pathway for the loss of soil P in agricultural systems; however, information regarding soil aggregate-associated colloidal P (Pcoll) is lacking. To elucidate the effects of aggregate size on the potential loss of Pcoll in agricultural systems, soils (0–20 cm depth) from six land-use types were sampled in the Zhejiang province in the Yangtze River Delta region, China. The aggregate size fractions (2–8 mm, 0.26–2 mm, 0.053–0.26 mm and <0.053 mm) were separated using the wet sieving method. Colloidal P and other soil parameters in aggregates were analyzed. Results: Our study demonstrated that 0.26–2 mm small macroaggregates had the highest total P (TP) content. In acidic soils, the highest Pcoll content was observed in the 0.26–2 mm sized aggregate, while the lowest was reported in the <0.053 mm (silt+clay)-sized particles, the opposite of that revealed in alkaline and neutral soils. Paddy soils contained less Pcoll than other land-use types. The proportion of Pcoll in total dissolved P (TDP) was dominated by <0.053 mm (silt+clay)-sized particles. Aggregate size strongly influenced the loss potential of Pcoll in paddy soils, where Pcoll contributed up to 83% TDP in the silt+clay sized particles. The Pcoll content was positively correlated with TP, Al, Fe, and the mean weight diameter. Aggregate-associated total carbon (TC), total nitrogen (TN), C/P, and C/N had significant negative effects on the contribution of Pcoll to potential soil P loss. The Pcoll content of the aggregates was controlled by the aggregate-associated TP and Al content, as well as the soil pH value. The potential loss of Pcoll from aggregates was controlled by its organic matter content. Conclusion: We concluded that management practices that increase soil aggregate stability or its organic carbon content will limit Pcoll loss in agricultural systems.

scholarly journals Organic matter cycling along geochemical, geomorphic and disturbance gradients in forests and cropland of the African Tropics – Project TropSOC Database Version 1.0

2021 ◽  
Author(s):  
Sebastian Doetterl ◽  
Rodrigue Asifiwe ◽  
Geert Baert ◽  
Fernando Bamba ◽  
Marijn Bauters ◽  
...  
Keyword(s):  
Land Use ◽  
Tropical Soils ◽  
Soil Microbial Activity ◽  
Biogeochemical Cycles ◽  
Congo Basin ◽  
Data Repository ◽  
Land Conversion ◽  
Soil Geochemistry ◽  
Soil Microbial ◽  
Wide Range

Abstract. The African Tropics are hotspots of modern-day land-use change and are, at the same time, of great relevance for the cycling of carbon (C) and nutrients between plants, soils and the atmosphere. However, the consequences of land conversion on biogeochemical cycles are still largely unknown as they are not studied in a landscape context that defines the geomorphic, geochemically and pedological framework in which biological processes take place. Thus, the response of tropical soils to disturbance by erosion and land conversion is one of the great uncertainties in assessing the carrying capacity of tropical landscapes to grow food for future generations and in predicting greenhouse gas fluxes (GHG) from soils to the atmosphere and, hence, future earth system dynamics. Here, we describe version 1.0 of an open access database created as part of the project “Tropical soil organic carbon dynamics along erosional disturbance gradients in relation to variability in soil geochemistry and land use” (TropSOC). TropSOC v1.0 contains spatial and temporal explicit data on soil, vegetation, environmental properties and land management collected from 136 pristine tropical forest and cropland plots between 2017 and 2020 as part of several monitoring and sampling campaigns in the Eastern Congo Basin and the East African Rift Valley System. The results of several laboratory experiments focusing on soil microbial activity, C cycling and C stabilization in soils complement the dataset to deliver one of the first landscape scale datasets to study the linkages and feedbacks between geology, geomorphology and pedogenesis as controls on biogeochemical cycles in a variety of natural and managed systems in the African Tropics. The hierarchical and interdisciplinary structure of the TropSOC database allows for linking a wide range of parameters and observations on soil and vegetation dynamics along with other supporting information that may also be measured at one or more levels of the hierarchy. TropSOC’s data marks a significant contribution to improve our understanding of the fate of biogeochemical cycles in dynamic and diverse tropical African (agro-)ecosystems. TropSOC v1.0 can be accessed through the supplementary material provided as part of this manuscript or as a separate download via the websites of the Congo Biogeochemistry observatory and the GFZ data repository where version updates to the database will be provided as the project develops.

scholarly journals Changes in physical properties and organic carbon of a Kandiudox fertilized with manure

2016 ◽  
Vol 46 (5) ◽  
pp. 809-814 ◽  
Author(s):  
Andréia Patricia Andrade ◽  
Luiz Paulo Rauber ◽  
Álvaro Luiz Mafra ◽  
Dilmar Baretta ◽  
Márcio Gonçalves da Rosa ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Physical Properties ◽  
C:N Ratio ◽  
Aggregate Stability ◽  
Clay Content ◽  
Penetration Resistance ◽  
Native Forest ◽  
Pig Slurry ◽  
Land Use And Management

ABSTRACT: Successive applications of pig slurry and poultry manure can improve the soil structure, according to the land use conditions and amounts applied. This study evaluated the effect of manure fertilization on the physical properties and organic carbon of a Rhodic Kandiudox. Treatments included land use and management and time of pig slurry and poultry litter application, namely: native forest (NF); yerba mate after 20 years of animal waste application (YM20); pasture after 15 years of application (P15); grassland after 20 years of manuring (PP20); grassland after 3 years of manuring (P3); pasture without application (P0), maize after 20 years of application (M20); and maize after 7 years of application (M7). Soil samples were collected in the 0-5, 5-10 and 10-20cm layers, in which density, porosity, aggregate stability, flocculation, penetration resistance, available water, and total clay content, total and particulate organic carbon, and C:N ratio were analyzed. The total organic carbon is sensitive to management and was not related to waste application, except in the 10-20cm layer of ryegrass pasture after three years of manuring. Reponses to waste application and land use and management systems were observed in the variables soil density and penetration resistance.

SOME TRENDS IN GRASSLAND FARMING IN EUROPE

1977 ◽  
pp. 5-19
Author(s):  
R.W. Brougham
Keyword(s):  
Land Use ◽  
Crude Protein ◽  
Energy Usage ◽  
Hill Country ◽  
Wide Range

IN an assessment such as this, one could cover a wide range of topics fairly shallowly or a lesser number in a bit more depth. I have opted for the latter. The topics discussed will embrace some trends in dairying, beef farming, sheep farming, hill country farming, and land use generally, species and variety usage in grassland farming, use of crude protein produced from pasture, and some implications of energy usage.

The way of value of Correlation of genomic DNA microsatellite loci and live weight of Chukchi reindeer

2020 ◽  
pp. 27-32
Author(s):  
V. Dodokhov ◽  
N. Pavlova ◽  
T. Rumyantseva ◽  
L. Kalashnikova
Keyword(s):  
Microsatellite Markers ◽  
Agricultural Production ◽  
Live Weight ◽  
Biodiversity Loss ◽  
Tribal Community ◽  
High Germination ◽  
Wide Range ◽  
The Mean ◽  
High Level ◽  
Dna Microsatellite

The article presents the genetic characteristic of the Chukchi reindeer breed. The object of the study was of the Chukchi reindeer. In recent years, the number of reindeer of the Chukchi breed has declined sharply. Reduced reindeer numbers could lead to biodiversity loss. The Chukchi breed of deer has good meat qualities, has high germination viability and is adapted in adverse tundra conditions of Yakutia. Herding of the Chukchi breed of deer in Yakutia are engaged only in the Nizhnekolymsky district. There are four generic communities and the largest of which is the agricultural production cooperative of nomadic tribal community «Turvaurgin», which was chosen to assess the genetic processes of breed using microsatellite markers: Rt6, BMS1788, Rt 30, Rt1, Rt9, FCB193, Rt7, BMS745, C 143, Rt24, OheQ, C217, C32, NVHRT16, T40, C276. It was found that microsatellite markers have a wide range of alleles and generally have a high informative value for identifying of genetic differences between animals and groups of animal. The number of identified alleles is one of the indicators of the genetic diversity of the population. The total number of detected alleles was 127. The Chukchi breed of deer is characterized by a high level of heterozygosity, and the random crossing system prevails over inbreeding in the population. On average, there were 7.9 alleles (Na) per locus, and the mean number of effective alleles (Ne) was 4.1. The index of fixation averaged 0.001. The polymorphism index (PIC) ranged from 0.217 to 0.946, with an average of 0.695.

COVID-19 Outbreak Prediction with Machine Learning

2020 ◽  
Author(s):  
Sina Faizollahzadeh Ardabili ◽  
Amir Mosavi ◽  
Pedram Ghamisi ◽  
Filip Ferdinand ◽  
Annamaria R. Varkonyi-Koczy ◽  
...  
Keyword(s):  
Machine Learning ◽  
Prediction Models ◽  
Fuzzy Inference ◽  
Control Measures ◽  
Future Research ◽  
Complex Nature ◽  
Inference System ◽  
Wide Range ◽  
Standard Models ◽  
High Level

Several outbreak prediction models for COVID-19 are being used by officials around the world to make informed-decisions and enforce relevant control measures. Among the standard models for COVID-19 global pandemic prediction, simple epidemiological and statistical models have received more attention by authorities, and they are popular in the media. Due to a high level of uncertainty and lack of essential data, standard models have shown low accuracy for long-term prediction. Although the literature includes several attempts to address this issue, the essential generalization and robustness abilities of existing models needs to be improved. This paper presents a comparative analysis of machine learning and soft computing models to predict the COVID-19 outbreak as an alternative to SIR and SEIR models. Among a wide range of machine learning models investigated, two models showed promising results (i.e., multi-layered perceptron, MLP, and adaptive network-based fuzzy inference system, ANFIS). Based on the results reported here, and due to the highly complex nature of the COVID-19 outbreak and variation in its behavior from nation-to-nation, this study suggests machine learning as an effective tool to model the outbreak. This paper provides an initial benchmarking to demonstrate the potential of machine learning for future research. Paper further suggests that real novelty in outbreak prediction can be realized through integrating machine learning and SEIR models.

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