Restoration and rehabilitation of degraded land in arid and semiarid environments: Editorial

info:eu-repo/semantics/publishedVersio

Biocrust amendments to topsoils facilitate biocrust restoration in a post-mining arid environment

Soil cryptogamic biocrusts provide many ecological functions in arid zone ecosystems, though their natural reestablishment in disturbed areas is slow. Accelerating reestablishment of biocrusts may facilitate the establishment of vascular plant communities within the timeframes of restoration targets (typically 5–15 years). One technique is to inoculate the soil surface using slurries of biocrust material harvested from another site. However, this is destructive to donor sites, and hence the potential to dilute slurries will govern the feasibility of this practice at large spatial scales. We conducted a replicated experiment on a disturbed mine site to test the individual and combined effects of two strategies for accelerating soil cryptogamic biocrust reestablishment: (1) slurry inoculation using biocrust material harvested from native vegetation; and (2) the use of psyllium husk powder as a source of mucilage to bind the soil surface, and to potentially provide a more cohesive substrate for biocrust development. The experiment comprised 90 experimental plots across six treatments, including different dilutions of the biocrust slurries and treatments with and without psyllium. Over 20 months, the reestablishing crust was dominated by cyanobacteria (including Tolypothrix distorta and Oculatella atacamensis), and these established more rapidly in the inoculated treatments than in the control treatments. The inoculated treatments also maintained this cover of cyanobacteria better through prolonged adverse conditions. The dilute biocrust slurry, at 1:100 of the biocrust in the remnant vegetation, performed as well as the 1:10 slurry, suggesting that strong dilution of biocrust slurry may improve the feasibility of using this technique at larger spatial scales. Psyllium husk powder did not improve biocrust development but helped to maintain a soil physical crust through hot, dry, and windy conditions, and so the potential longer-term advantages of psyllium need to be tested. Copyright © 2022 Schultz, Sluiter, Allen, Machado-de-Lima and Muñoz-Rojas

Soil, site, and management factors affecting cadmium concentration in cacao-growing soils

Soil contamination by potentially toxic trace elements (PTEs) such as Cadmium (Cd), is a major environmental concern because of its potential implications to human health. Cacao-based products have been identified as food sources with relatively high Cd contents. Here, we assessed Cd concentrations of cacao-growing soils in four major agricultural regions with contrasting climates in Peru, one of the main exporters of cacao products worldwide. At each study site (n = 40) a broad range of potential factors affecting Cd concentration in soils, i.e., site, soil and management, were evaluated. Concentrations of Cd ranged between 1.1-3.2 mg kg-1. Mean values per region were below 2.7 mg kg-1, usually established as upper-limit for non-polluted soils. Cadmium concentrations were significantly (p < 0.001) higher in sites at higher elevations and in a temperate, drier climate. Cadmium correlated positively with pH (r = 0.57; p < 0.05) and was higher (p < 0.001) in alluvial sediments and Leptosols. Management factors (cacao variety, cultivation year, management practices) and agroecology did not affect Cd concentrations directly. Overall, this study highlights the importance of considering a broad range of both natural and anthropogenic factors to evaluate Cd concentrations in cacao-growing soils and contribute to effective and sustainable cacao production by improving land management and plannin

Soil biodiversity and organic carbon are essential to reverse desertification

La biodiversidad y el carbono orgánico del suelo, así como la interacción entre ambos, juegan papeles esenciales en el mantenimiento y regulación de los servicios ecosistémicos de las zonas secas, desde la fertilidad del suelo a la producción de alimentos. El cambio climático y los impactos antrópicos pueden provocar pérdidas en la biodiversidad y carbono del suelo, lo cual puede resultar en alteraciones de los ciclos del carbono y la funcionalidad de los ecosistemas derivando en procesos acelerados de desertificación. Es necesario, por tanto, mejorar nuestro conocimiento sobre la compleja diversidad biológica del suelo, así como su interacción con el carbono orgánico en las zonas secas. Esto nos permitirá diseñar estrategias efectivas para promover el secuestro de carbono en el suelo, contribuyendo así a revertir los procesos de degradación y desertificación. En esta revisión discutimos la importancia de la biodiversidad y el carbono orgánico del suelo de las zonas secas en un contexto de cambio global, definiendo la relación entre ambos y su respuesta a factores climáticos y degradación. También destacamos el uso de herramientas avanzadas tales como la genómica, y practicas relevantes de manejo del suelo que nos permitan incrementar los contenidos de carbono y mejorar la diversidad y funcionalidad de suelo en las zonas secas, con el fin último de prevenir y revertir la desertificación.Soil biodiversity, organic carbon, and their interactions, play critical roles for the maintenance and regulation of ecosystem services in drylands, including soil fertility and food production, among others. Climate change and anthropogenic impacts can result in soil carbon and biodiversity decreases, which can cause alterations of the carbon cycle and the loss of essential ecosystem functions. It is therefore crucial to advance our knowledge on the complex soil biological diversity, and its interactions with the soil organic carbon in drylands. This information will allow us to design effective strategies for carbon sequestration, thus contributing to reverse desertification. In this review, we discuss the importance of the soil biodiversity and organic carbon in drylands in a global change context and underline their interactions and their responses to climate change and degradation. We also highlight the use of novel techniques recently developed, including genomics, and effective soil management practices for promoting soil biodiversity and enhancing soil carbon levels, to ultimately, halt degradation and desertification.Australian Research Council Discovery Early Career Research Award DE180100570Ministerio de Ciencia e Innovación de España PID2020-115813RA-I00Junta de Andalucía P20_00879Hermon Slade Foundation HSF18-

Biocrust Amendments to Topsoils Facilitate Biocrust Restoration in a Post-mining Arid Environment

Soil cryptogamic biocrusts provide many ecological functions in arid zone ecosystems, though their natural reestablishment in disturbed areas is slow. Accelerating reestablishment of biocrusts may facilitate the establishment of vascular plant communities within the timeframes of restoration targets (typically 5–15 years). One technique is to inoculate the soil surface using slurries of biocrust material harvested from another site. However, this is destructive to donor sites, and hence the potential to dilute slurries will govern the feasibility of this practice at large spatial scales. We conducted a replicated experiment on a disturbed mine site to test the individual and combined effects of two strategies for accelerating soil cryptogamic biocrust reestablishment: (1) slurry inoculation using biocrust material harvested from native vegetation; and (2) the use of psyllium husk powder as a source of mucilage to bind the soil surface, and to potentially provide a more cohesive substrate for biocrust development. The experiment comprised 90 experimental plots across six treatments, including different dilutions of the biocrust slurries and treatments with and without psyllium. Over 20 months, the reestablishing crust was dominated by cyanobacteria (including Tolypothrix distorta and Oculatella atacamensis), and these established more rapidly in the inoculated treatments than in the control treatments. The inoculated treatments also maintained this cover of cyanobacteria better through prolonged adverse conditions. The dilute biocrust slurry, at 1:100 of the biocrust in the remnant vegetation, performed as well as the 1:10 slurry, suggesting that strong dilution of biocrust slurry may improve the feasibility of using this technique at larger spatial scales. Psyllium husk powder did not improve biocrust development but helped to maintain a soil physical crust through hot, dry, and windy conditions, and so the potential longer-term advantages of psyllium need to be tested

Spatial Gradients of Intensity and Persistence of Soil Water Repellency Under Different Forest Types in Central Mexico

Organic residues release hydrophobic compounds to the soil that may induce soil water repellency (WR), which may inhibit infiltration andincrease runoff and soil loss rates. Although there are many studies on soil WR through the world, very few investigations have been con-ducted in Mexican areas. This paper studies the natural background of soil WR in soils from central Mexico under representative forest types,analyzing the spatial distribution of soil WR in relation with tree canopy, vegetation cover and main soil chemical (pH, CaCO3, organic Ccontent and exchangeable cations) and physical properties (texture). The water drop penetration time and the ethanol tests were used to assesspersistence and intensity of soil WR, respectively. Although soil WR was not related with soil properties, it decreased strongly from soil be-low the canopy of conifers to soil below oaks. When different types of vegetation cover were considered, the proportion of water-repellentsoil increased following the sequence: bare soil < shrubs and herbaceous plants < shrubs < trees from fir, fir-pine-oak and pine-oak forest.We found an inverse relation with distance to the tree trunks, contributing to create a patchy pattern of soil WR, with soils under the canopyof conifers showing the most severe WR levels. The spatial distribution of soil WR is also conditioned by microclimatic gradients, as per-sistence and intensity of soil WR were usually lower in shaded areas (upslope transects from the tree trunks), where soil moisture contentis expected to be higher on average through the year. Copyright © 2016 John Wiley & Sons, LtdMinisterio de Economía y Competitividad CGL2013-47862-C2-1-RMinisterio de Economía y Competitividad CGL 2012-38655-C04-0

Analysis of the geometric parameters influence in PCB fixtures for 2D multipole magnetization patterning of thin layer micro-magnets

Magnetic actuators, magnetic gears, vibrational energy harvesters and other micro-electromagnetic devices requires micro-magnetic rotors with alternant magnetizations to optimize their performance. Different approaches have been used for multipole magnetization of micro-magnets like fixed micro-fixtures, thermomagnetic patterning or laser machining. The main limitation of the previous techniques is that the inversion of the magnetic polarizations is only partially done. In this work, a concept based on 2D multipole magnetization printing of micro-magnets is proposed and analyzed to overcome current limitations. The fixtures are designed to be printed on a standard 35 μm PCB. The dependence of the magnetizing field with respect to the geometrical parameter of the fixture is analyzed. Maps of the required current for the magnetizing fields are also given. Some design recommendations to optimize the magnetizing field and to minimize current, thus the heat, are given.Universidad de Alcal

Strategic Management of Grazing Grassland Systems to Maintain and Increase Organic Carbon in Soils

Understanding management-induced C sequestration potential in soils under agriculture, forestry, and other land use systems and their quantification to offset increasing greenhouse gases are of global concern. This chapter reviews management-induced changes in C storage in soils of grazing grassland systems, their impacts on ecosystem functions, and their adaptability and needs of protection across socio-economic and cultural settings. In general, improved management of grassland/pasture such as manuring/slurry application, liming and rotational grazing, and low to medium livestock units could sequester C more than under high intensity grazing conditions. Converting cultivated land to pasture, restoration of degraded land, and maximizing pasture phases in mixed-cropping, pasture with mixed-livestock, integrated forestry-pasturage of livestock (silvopastoral) and crop-forestry-pasturage of livestock (agro-silvopastoral) systems could also maintain and enhance soil organic C density (SOCρ). In areas receiving low precipitation and having high erodibility, grazing exclusion might restore degraded grasslands and increase SOCρ. Yet, optimizing C sequestration rates, sowing of more productive grass varieties, judicial inorganic and organic fertilization, rotational grazing, and other climate-resilient approaches could improve overall farm productivity and profitability and attain sustainability in livestock farming systems

Modelling soil organic carbon stocks in global change scenarios: a CarboSOIL application

Global climate change, as a consequence of the increasing levels of atmospheric CO2 concentration, may significantly affect both soil organic C storage and soil capacity for C sequestration. CarboSOIL is an empirical model based on regression techniques and developed as a geographical information system tool to predict soil organic carbon (SOC) contents at different depths. This model is a new component of the agro-ecological decision support system for land evaluation MicroLEIS, which assists decision-makers in facing specific agro-ecological problems, particularly in Mediterranean regions. In this study, the CarboSOIL model was used to study the effects of climate change on SOC dynamics in a Mediterranean region (Andalusia, S Spain). Different downscaled climate models were applied based on BCCR-BCM2, CNRMCM3, and ECHAM5 and driven by SRES scenarios (A1B, A2 and B2). Output data were linked to spatial data sets (soil and land use) to quantify SOC stocks. The CarboSOIL model has proved its ability to predict the short-medium- and long-term trends (2040s, 2070s and 2100s) of SOC dynamics and sequestration under projected future scenarios of climate change. Results have shown an overall trend towards decreasing of SOC stocks in the upper soil sections (0–25 cm and 25–50 cm) for most soil types and land uses, but predicted SOC stocks tend to increase in the deeper soil section (0–75 cm). Soil types as Arenosols, Planosols and Solonchaks and land uses as “permanent crops” and “open spaces with little or no vegetation” would be severely affected by climate change with large decreases of SOC stocks, in particular under the medium–high emission scenario A2 by 2100. The information developed in this study might support decision-making in land management and climate adaptation strategies in Mediterranean regions, and the methodology could be applied to other Mediterranean areas with available soil, land use and climate data.Ministerio de Economía y CompetitividadJunta de Andalucí