scholarly journals Mapping and Quantifying Comprehensive Land Degradation Status Using Spatial Multicriteria Evaluation Technique in the Headwaters Area of Upper Blue Nile River

2021 ◽  
Vol 13 (4) ◽  
pp. 2244
Author(s):  
Alelgn Ewunetu ◽  
Belay Simane ◽  
Ermias Teferi ◽  
Benjamin F. Zaitchik
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Land Degradation ◽  
Soil Loss ◽  
Chemical Degradation ◽  
Nile River ◽  
Biological Degradation ◽  
Blue Nile ◽  
The North ◽  
High Level

Mapping and quantifying land degradation status is important for identifying vulnerable areas and to design sustainable landscape management. This study maps and quantifies land degradation status in the north Gojjam sub-basin of the Upper Blue Nile River (Abbay) using GIS and remote sensing integrated with multicriteria analysis (MCA). This is accomplished using a combination of biological, physical, and chemical land degradation indicators to generate a comprehensive land degradation assessment. All indicators were standardized and weighted using analytical hierarchy and pairwise comparison techniques. About 45.3% of the sub-basin was found to experience high to very high soil loss risk, with an average soil loss of 46 t ha−1yr−1. More than half of the sub-basin was found to experience moderate to high level of biological degradation (low vegetation status and low soil organic matter level). In total, 80.2% of the area is characterized as having a moderate level of physical land degradation. Similarly, the status of chemical degradation for about 55.8% and 39% of the sub-basin was grouped as low and moderate, respectively. The combined spatial MCA of biological, chemical, and physical land degradation indicators showed that about 1.14%, 32%, 35.4%, and 30.5% of the sub-basin exhibited very low, low, moderate, and high degradation level, respectively. This study has concluded that soil erosion and high level of biological degradation are the most important indicators of land degradation in the north Gojjam sub-basin. Hence, the study suggests the need for integrated land management practices to reduce land degradation, enhance the soil organic matter content, and increase the vegetation cover in the sub-basin.

A molecular dynamic study of Soil Organic Matter stabilization mechanisms

2021 ◽  
Author(s):  
Edgar Galicia-Andrés ◽  
Yerko Escalona ◽  
Peter Grančič ◽  
Chris Oostenbrink ◽  
Daniel Tunega ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Clay Mineralogy ◽  
Metal Cations ◽  
Dense Matter ◽  
Chemical Degradation ◽  
Molecular Graphics ◽  
Organic Matter Stabilization ◽  
Reactive Surfaces

<p>It is well known that some fractions of soil organic matter (SOM) can resist to physical and (bio)chemical degradation which can be attributed to factors ranging from molecular properties to the preference for digesting other molecular species by microorganisms. Some mechanisms, by which organic matter is protected, are often referred to as: physical stabilization through microaggregation, chemical stabilization by formation of SOM-mineral aggregates, and biochemical stabilization through the formation of recalcitrant SOM.</p><p>Protection mechanisms are responsible for the accumulation process of organic carbon, reducing the exposure of organic matter and making it less vulnerable to microbial, enzymatic or chemical attacks. In these mechanisms, water molecular bridges and metal cation bridges play a key role. Cation bridges serve as aggregation sites on humic substances, forming dense matter, in comparison to systems where bridges are missing. This effect is enhanced in systems with cations at higher oxidation states.</p><p>By using the modeler tool developed in our group (Vienna Soil–Organic–Matter Modeler, VSOMM2) (Escalona et al., 2021), we generated aggregate models of humic substances at atomistic scale reflecting the diversity in composition, size and conformations of the constituting molecules. Further, we built models of organo-clay aggregates using kaolinite and montmorillonite as typical soil minerals. This allowed a systematic study to understand the effect of the surrounding environment at microscopic scale, not fully accessible experimentally.</p><p>Molecular simulations of the adsorption process of SOM aggregates on the reactive surfaces of led to two observations: 1) the humic substances aggregates were able to interact with the reactive surfaces mainly via hydrogen bonds forming stable organic matter-clay complexes and 2) the aggregates subsequently lost rigidity and stability after metal cations removing, consequently leading to a gradual loss of humic substance molecules, evidencing the role of metal cations in the protection mechanism of soil organic matter aggregates and possibly explaining its recalcitrance (Galicia-Andrés et al., 2021).</p><p>References</p><ul><li>Escalona, Y., Petrov, D., & Oostenbrink, C. (2021). Vienna soil organic matter modeler 2 (VSOMM2). Journal of Molecular Graphics and Modelling, 103, 107817. https://doi.org/10.1016/j.jmgm.2020.107817</li> <li>Galicia-Andrés, E., Grančič, P., Gerzabek, M. H., Oostenbrink, C., & Tunega, D. (2021). Modeling of interactions in natural and synthetic organoclays. In I. C. Sainz Diaz (Ed.), Computational modeling in clay mineralogy.</li> </ul>

Measuring Soil Loss and Subsequent Nutrient and Organic Matter Loss on Farmland

2017 ◽  
Author(s):  
Vito Ferro ◽  
Vincenzo Bagarello
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Loss ◽  
Soil Structure ◽  
Overland Flow ◽  
Organic Matter Content ◽  
Matter Content ◽  
Water Infiltration ◽  
Surface Erosion ◽  
Rill Erosion

Field plots are often used to obtain experimental data (soil loss values corresponding to different climate, soil, topographic, crop, and management conditions) for predicting and evaluating soil erosion and sediment yield. Plots are used to study physical phenomena affecting soil detachment and transport, and their sizes are determined according to the experimental objectives and the type of data to be obtained. Studies on interrill erosion due to rainfall impact and overland flow need small plot width (2–3 m) and length (< 10 m), while studies on rill erosion require plot lengths greater than 6–13 m. Sites must be selected to represent the range of uniform slopes prevailing in the farming area under consideration. Plots equipped to study interrill and rill erosion, like those used for developing the Universal Soil Loss Equation (USLE), measure erosion from the top of a slope where runoff begins; they must be wide enough to minimize the edge or border effects and long enough to develop downslope rills. Experimental stations generally include bounded runoff plots of known rea, slope steepness, slope length, and soil type, from which both runoff and soil loss can be monitored. Once the boundaries defining the plot area are fixed, a collecting equipment must be used to catch the plot runoff. A conveyance system (H-flume or pipe) carries total runoff to a unit sampling the sediment and a storage system, such as a sequence of tanks, in which sediments are accumulated. Simple methods have been developed for estimating the mean sediment concentration of all runoff stored in a tank by using the vertical concentration profile measured on a side of the tank. When a large number of plots are equipped, the sampling of suspension and consequent oven-drying in the laboratory are highly time-consuming. For this purpose, a sampler that can extract a column of suspension, extending from the free surface to the bottom of the tank, can be used. For large plots, or where runoff volumes are high, a divisor that splits the flow into equal parts and passes one part in a storage tank as a sample can be used. Examples of these devices include the Geib multislot divisor and the Coshocton wheel. Specific equipment and procedures must be employed to detect the soil removed by rill and gully erosion. Because most of the soil organic matter is found close to the soil surface, erosion significantly decreases soil organic matter content. Several studies have demonstrated that the soil removed by erosion is 1.3–5 times richer in organic matter than the remaining soil. Soil organic matter facilitates the formation of soil aggregates, increases soil porosity, and improves soil structure, facilitating water infiltration. The removal of organic matter content can influence soil infiltration, soil structure, and soil erodibility.

Soils, Science and Community ActioN (SoilSCAN) to reduce land degradation in East Africa

2021 ◽  
Author(s):  
Alex Taylor ◽  
Claire Kelly ◽  
Maarten Wynants ◽  
Aloyce Patrick ◽  
Francis Mkilema ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Erosion ◽  
Citizen Science ◽  
Land Degradation ◽  
Soil Health ◽  
Community Action ◽  
East African ◽  
Small Catchment ◽  
Management Interventions

&lt;p&gt;East African farming communities face complex challenges regarding food and feed productivity. Primary production systems are under stress, nutritional choices are changing and the relationship between development and agriculture is undergoing profound transformation. In the face of severe threat of soil erosion, East African agro-pastoral systems are now at a tipping point and there has never been a greater urgency for evidence-led sustainable land management interventions to reverse degradation of natural resources that support food and water security. A key barrier, however, is a lack of high spatial resolution soil health data wherein collecting such information is beyond conventional research means. This research tests whether bridging this data gap can be achieved through a coordinated citizen science programme. Accessible and portable technology is currently available in the form of hand-held soil scanners that can enable farmers to become citizen scientists empowered to collect data to establish research data bases that support critical landscape decisions. The aim of the work was to test the potential for using soil scanners as a tool for mapping whole community soil health characteristics, using soil organic matter as an indicator, down to farm-scale; a resolution that is beyond that achievable in conventional research, with the ultimate objective to deliver information that empowers stakeholders to create a sustainable community landscape plan.&lt;/p&gt;&lt;p&gt;Key outcomes included:&lt;/p&gt;&lt;p&gt;(1) A training document for the usage of the soil scanner that includes a list of potential problems and their solutions. Moreover, a training session was organised in the Tanzanian partner institution to build capacity for the continuation of the project, wherein local researchers were trained in the application of the &amp;#8216;Agrocares&amp;#8217; soil scanner to support continuing community engagement.&lt;/p&gt;&lt;p&gt;(2) Local farmers being provided an opportunity to circumvent traditional power and knowledge inequities. During the introductory meeting and field measurements, we noticed the development of locally-embedded scientific interests and skills that foster stronger community ownership and engagement in action research.&lt;/p&gt;&lt;p&gt;(3) A high resolution soil organic matter and nutrient status dataset in small-catchment and community setting. The citizen science data contributes to soil process and hydrological understanding of East African landscapes, which besides direct contribution to the scientific understanding, also supports co-design of effective management solutions to the soil erosion and land degradation challenges.&lt;/p&gt;&lt;p&gt;The inclusion of &amp;#8216;big data&amp;#8217; digital data training and sharing platforms and has the potential to create more robust and better informed collective decision-making, as well as identifying key data gaps. Further it can expand the utility and applicability of existing techniques and data sets beyond the reach of conventional research. Challenges and opportunities for wider use of soil scanning technology by community groups are evaluated.&lt;/p&gt;

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