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  • 1
    Language: English
    In: Agriculture, Ecosystems and Environment, 01 August 2017, Vol.246, pp.210-220
    Description: Improved soil management in rainfed Mediterranean agroecosystems can be a powerful strategy to mitigate the current atmospheric CO increase, through soil carbon sequestration and stabilization. In this work, we assess the effects of different soil management practices (conventional tillage, CT, reduced tillage, RT, reduced tillage plus green manure, RTG, and no tillage, NT) on soil CO flux dynamics and carbon sequestration in two organic rainfed almond ( Mill.) orchards under semiarid conditions. Soil CO flux, temperature, and moisture were measured monthly over two-three years, and shortly after tillage operations. The soil aggregation distribution (including micro-aggregates occluded within macro-aggregates) and associated organic carbon content were measured after four years of implementation. No significant differences in CO emissions among the soils subjected to the distinct management practices were observed at either site. On the one hand, shifting from CT to RT or RTG increased the OC content by 56% on average in all aggregate sizes. On the other hand, suppressing tillage only increased the OC content (by 24%) in the macro-aggregates. Moreover, improved soil management practices modulated the response of soil CO flux to temperature and moisture in these semiarid Mediterranean agroecosystems. According to our results, soil CO flux under the conventional tillage treatment was more sensitive to temperature increments than with the reduced tillage treatments, indicating that bare soils will be more vulnerable to organic carbon mineralization with ongoing global warming. On the contrary, the incorporation of plant residues under the reduced tillage treatments promoted soil aggregation and organic carbon preservation, making soils more resilient to abrupt changes in temperature and moisture under these treatments.
    Keywords: Improved Soil Management ; Cover Crop Mulches ; Almond Orchards ; Soil Co2 Emissions ; Carbon Sequestration ; Occluded Micro-Aggregates ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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  • 2
    Language: English
    In: Journal of Soils and Sediments, Feb, 2013, Vol.13(2), p.265(13)
    Description: Byline: Juan Albaladejo (1), Roque Ortiz (2), Noelia Garcia-Franco (1), Antonio Ruiz Navarro (1), Maria Almagro (1), Javier Garcia Pintado (1), Maria Martinez-Mena (1) Keywords: Carbon sequestration potential; Control factors of soil organic carbon; Impact of global change; Vertical distribution of soil organic carbon Abstract: Purpose The sensitivity of soil organic carbon to global change drivers, according to the depth profile, is receiving increasing attention because of its importance in the global carbon cycle and its potential feedback to climate change. A better knowledge of the vertical distribution of SOC and its controlling factors--the aim of this study--will help scientists predict the consequences of global change. Materials and methods The study area was the Murcia Province (S.E. Spain) under semiarid Mediterranean conditions. The database used consists of 312 soil profiles collected in a systematic grid, each 12 km.sup.2 covering a total area of 11,004 km.sup.2. Statistical analysis to study the relationships between SOC concentration and control factors in different soil use scenarios was conducted at fixed depths of 0--20, 20--40, 40--60, and 60--100 cm. Results and discussion SOC concentration in the top 40 cm ranged between 6.1 and 31.5 gkg.sup.-1, with significant differences according to land use, soil type and lithology, while below this depth, no differences were observed (SOC concentration 2.1--6.8 gkg.sup.-1). The ANOVA showed that land use was the most important factor controlling SOC concentration in the 0--40 cm depth. Significant differences were found in the relative importance of environmental and textural factors according to land use and soil depth. In forestland, mean annual precipitation and texture were the main predictors of SOC, while in cropland and shrubland, the main predictors were mean annual temperature and lithology. Total SOC stored in the top 1 m in the region was about 79 Tg with a low mean density of 7.18 kgCm.sup.-3. The vertical distribution of SOC was shallower in forestland and deeper in cropland. A reduction in rainfall would lead to SOC decrease in forestland and shrubland, and an increase of mean annual temperature would adversely affect SOC in croplands and shrubland. With increasing depth, the relative importance of climatic factors decreases and texture becomes more important in controlling SOC in all land uses. Conclusions Due to climate change, impacts will be much greater in surface SOC, the strategies for C sequestration should be focused on subsoil sequestration, which was hindered in forestland due to bedrock limitations to soil depth. In these conditions, sequestration in cropland through appropriate management practices is recommended. Author Affiliation: (1) Soil and Water Conservation Department, CEBAS-CSIC (Spanish Research Council), Campus de Espinardo, 30100, Murcia, Spain (2) Agricultural Chemistry, Geology and Soil Science Department, Murcia University, Campus de Espinardo, 30100, Murcia, Spain Article History: Registration Date: 08/10/2012 Received Date: 04/06/2012 Accepted Date: 08/10/2012 Online Date: 23/10/2012 Article note: Responsible editor: Zucong Cai
    Keywords: Greenhouse Effect -- Analysis ; Lithofacies -- Analysis ; Land Use -- Analysis ; Global Temperature Changes -- Analysis ; Rain -- Analysis ; Carbon Cycle -- Analysis ; Soil Carbon -- Analysis ; Land Use Controls -- Analysis ; Forest Management -- Analysis
    ISSN: 1439-0108
    E-ISSN: 16147480
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  • 3
    In: Land Degradation & Development, April 2018, Vol.29(4), pp.1041-1053
    Description: The Food and Agriculture Organization considers around a quarter of global land to be degraded. Of particular concern are threats to soils in water‐limited regions, which are critical to food and economic security in countries across the globe but are under increasing pressure due to human use and climatic forcing. These soils have been used to feed and provide resources and services to human societies for millennia, with earliest land‐uses dating back to prehistoric times. With the adoption of modern, frequently unsuitable agricultural practices combined with the population pressures and shifting consumption patterns, soils in water‐limited regions have come under threat, resulting in degradation and in worst‐case scenarios, desertification. Here, we review the current state of soils in water‐limited environments and provide a guide to management for conservation and restoration of these fragile soils. Options to manage specific threats to soil functionality, namely, erosion, soil salinity, loss of functionality due to landscape homogenization, degradation of soil organic matter, and climate vulnerability are presented for specific land‐uses using a whole‐system approach management framework.
    Keywords: Drylands ; Erosion ; Landscape Homogenization ; Salinization ; Soil Organic Matter
    ISSN: 1085-3278
    E-ISSN: 1099-145X
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  • 4
    Language: English
    In: Biogeosciences Discussions, 10/05/2018, pp.1-32
    ISSN: Biogeosciences Discussions
    E-ISSN: 1810-6285
    Source: CrossRef
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  • 5
    Language: English
    In: Journal of Soils and Sediments, 2013, Vol.13(2), pp.265-277
    Keywords: Carbon sequestration potential ; Control factors of soil organic carbon ; Impact of global change ; Vertical distribution of soil organic carbon
    ISSN: 1439-0108
    E-ISSN: 1614-7480
    Source: Springer Science & Business Media B.V.
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  • 6
    Language: English
    In: European Journal of Agronomy, August 2013, Vol.49, pp.149-157
    Description: Sustainable farming practices can be beneficial or detrimental to crop production in the short-term, which will strongly determine their appeal to farmers. We evaluated the effects of several sustainable practices on soil properties, plant nutrition and ecophysiology and crop yield in a semiarid agroecosystem. A three-year randomised experiment was conducted in a rainfed almond grove where the initial soil management was reduced tillage. Two alternative treatments were evaluated: reduced tillage plus green manure and no-tillage. The following soil and plant parameters were measured once per year: soil organic carbon, total nitrogen and P ; foliar N, P, δ C and δ N and crop yield. We found that soil bulk density increased significantly with no-tillage. Leaf δ N was positively associated with soil fertility, foliar nutrient concentrations and crop yield across treatments. Leaf δ C, N and crop yield were strongly positively associated across treatments in every year of the study. Reduced tillage treatments displayed higher leaf δ N, δ C, N and crop yield than the no-tillage treatment, indicating a sharp decrease in the leaf nitrogen status and intrinsic water use efficiency of almond trees during the transition from reduced tillage to no-tillage. In semiarid agroecosystems where soils are prone to compaction, some tillage is required to maintain optimal crop production in rainfed almonds.
    Keywords: Nutrient Uptake ; Soil Property ; Foliar Δ13c ; Foliar Δ15n ; Soil Compaction ; Green Manure ; Agriculture
    ISSN: 1161-0301
    E-ISSN: 1873-7331
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  • 7
    Language: English
    In: European journal of agronomy, 2013, Vol.49, pp.149-157
    Description: Sustainable farming practices can be beneficial or detrimental to crop production in the short-term, which will strongly determine their appeal to farmers. We evaluated the effects of several sustainable practices on soil properties, plant nutrition and ecophysiology and crop yield in a semiarid agroecosystem. A three-year randomised experiment was conducted in a rainfed almond grove where the initial soil management was reduced tillage. Two alternative treatments were evaluated: reduced tillage plus green manure and no-tillage. The following soil and plant parameters were measured once per year: soil organic carbon, total nitrogen and Pₒₗₛₑₙ; foliar N, P, δ¹³C and δ¹⁵N and crop yield. We found that soil bulk density increased significantly with no-tillage. Leaf δ¹⁵N was positively associated with soil fertility, foliar nutrient concentrations and crop yield across treatments. Leaf δ¹³C, Nfₒₗᵢₐᵣ and crop yield were strongly positively associated across treatments in every year of the study. Reduced tillage treatments displayed higher leaf δ¹⁵N, δ¹³C, Nfₒₗᵢₐᵣ and crop yield than the no-tillage treatment, indicating a sharp decrease in the leaf nitrogen status and intrinsic water use efficiency of almond trees during the transition from reduced tillage to no-tillage. In semiarid agroecosystems where soils are prone to compaction, some tillage is required to maintain optimal crop production in rainfed almonds. ; p. 149-157.
    Keywords: Soil Organic Carbon ; Agroecosystems ; Soil Fertility ; Soil Compaction ; No-Tillage ; Sustainable Agriculture ; Reduced Tillage ; Crop Yield ; Green Manures ; Leaves ; Soil Density ; Nitrogen ; Nutrient Content ; Farmers ; Nitrogen Content ; Almonds ; Groves ; Dryland Farming ; Trees ; Water Use Efficiency ; Plant Nutrition
    ISSN: 1161-0301
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 8
    Language: English
    In: Agriculture, Ecosystems and Environment, 01 August 2019, Vol.280, pp.118-128
    Description: Grassland management and climate change may have profound effects on soil organic carbon (SOC) storage in temperate grasslands, but to date only limited information on the long-term SOC development derived from grassland monitoring sites is available. In 1986, the established 20 long-term grassland soil monitoring sites in the state of Bavaria, Germany. We analyzed SOC changes and their main controlling factors in these monitoring sites between 1989 and 2016 in four intervals using the machine learning algorithm conditional random forest. The results showed that changes of SOC stocks in grassland monitoring sites were affected by the multifactorial and interactive nature of changing climate conditions, pedogenic-topographic factors and management practices. Seasonal climate variables explained the highest variability of SOC stock changes in long-term grassland sites, followed by organic fertilizer application. Increasing autumn precipitation led to decreased SOC stocks, whereas increasing spring and summer precipitation led to increased SOC stocks on sites at high elevations with low slopes. Furthermore, we observed that the organic fertilizer application resulted in an increase and/or preservation of SOC stocks, whereas conventional farming with a low degree of organic fertilization resulted in SOC stock decreases. Regarding the acceleration of climate change and the complex interactions between site conditions, changing climate and management, there is an urgent need to collect improved management data in future long-term studies.
    Keywords: Random Forest ; Climate Change ; Seasonal Carbon Change ; Grassland Management ; Long-Term Experiments ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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  • 9
    Language: English
    Description: A nivel global se está produciendo una retroalimentación negativa en el ciclo terrestre del carbono con emisiones a la atmosfera de 3-6 Gt/año de CO2. Se estima que más de un 57% de la pérdida del C del reservorio terrestre es debido a la reducción del carbono orgánico del suelo (COS). Aunque, este proceso se puede revertir, mejorando la estructura del suelo a través de usos de suelo y prácticas de manejo sostenibles. Sin embargo, todavía hay necesidad de un mayor conocimiento científico sobre los mecanismos de estabilización del COS y los diferentes factores que intervienen en esa estabilización en zonas semiáridas. Esta tesis tiene como objetivo general llenar estos vacíos de conocimiento y proporcionar una base de datos y experiencia que permita determinar los mejores usos y prácticas de manejo sostenible en ambientes semiáridos. En el Capítulo 3 de esta tesis, se realizó un estudio a escala regional donde se determina la distribución de los contenidos de CO en el perfil del suelo, en función del tipo de uso, y se analizan los factores que controlan las variaciones en estos contenidos. Se establecen correlaciones entre los factores de control y la concentración de CO, para mejorar las predicciones sobre el impacto del cambio climático y uso del suelo sobre la materia orgánica de los suelos semiáridos. Los resultados mostraron que con las tendencias actuales del cambio climático, nuestras predicciones indican que los impactos, en el COS, serán mayores en la superficie, así, las estrategias para el secuestro de C deben estar focalizadas al secuestro en el subsuelo, preferentemente en áreas agrícolas, de suelos más profundos, mediante prácticas de manejo adecuadas. Teniendo en cuenta los resultados anteriores, los siguientes estudios de esta tesis estuvieron enfocados a adoptar medidas de protección y secuestro del CO en suelos semiáridos bajo dos de los usos más representativos: forestal y agrícola. En los capítulos 4 y 5 se estudió la dinámica de las propiedades del suelo, los stocks de CO y se discutieron los mecanismos de acumulación y estabilización del CO tras la reforestación de un matorral degradado con dos técnicas de reforestación. Los resultados mostraron que adecuadas técnicas de reforestación favorecen la capacidad potencial de secuestro de C de los ecosistemas reforestados y que pasados veinte años, aún están lejos de ser saturados, pudiendo continuar secuestrando C a medida que alcanzan la madurez. En la reforestación con adición de enmienda orgánica el aumento del pool de C lábil induce un aumento de la actividad microbiana, con cambios significativos en las comunidades de hongos. Estos cambios, promueven y activan los procesos de formación de nuevos macroagregados que actúan como núcleo de formación de microagregados ocluidos dentro de ellos y que están enriquecidos en CO, principalmente en la capa superficial. El capítulo 6 se estudia el efecto de diferentes prácticas de manejo en la dinámica y mecanismos de estabilización del COS. Los mayores aumentos en el total de CO del suelo y CO asociado a los agregados se han observado en el tratamiento de laboreo reducido y siembra verde (RTG) respecto al de no laboreo (NT), sugiriendo que la combinación de abono verde y laboreo reducido es una buena opción para el secuestro de CO: i) RTG representa continuos inputs de MO que, a su vez, activan: a) la protección física del CO a través de la formación de nuevos agregados y b) la protección físico-química asociado a las partículas minerales del suelo; y ii) es necesario un mínimo de laboreo porque favorece la incorporación de los restos vegetales a las capas más profundas del suelo, promoviendo así la formación de nuevos agregados.
    Description: At present, in the terrestrial carbon (C) cycle a negative feedback is occurring, with emission to the atmosphere of 3-6 Gt CO2 per year through soil organic carbon (SOC), with the subsequent acceleration of climatic change. A 57% of loss from terrestrial C pool is estimated to have arisen from depletion of SOC. This part of the C cycle could be managed by improving soil structure through adequate and sustainable land uses and sustainable land management practices. However, the stabilization mechanisms of SOC and its relationship with different abiotic and biotic factors of the soil, under different situations of land use and management practices, in semiarid-areas are still quite unknown. The general objective of this thesis is to fill these gaps in knowledge and provide a valid set of data to be able to recommend the best uses and sustainable management practices for soil conservation and mitigation of climate change in semiarid environments. Chapter 3 of this thesis, describes the estimation, at the regional scale, of the distribution of OC contents in the soil profile, depending on the type of use, and discusses the factors that control the variations in these contents. Correlations between these factors and the concentration of OC are established, to improve predictions of the impact of climate change and land use on the organic matter of semiarid soils. The results obtained showed that with due to climate change impacts will be much greater in surface SOC; the strategies for C sequestration should be focused on subsoil sequestration, which was hindered in forestland due to bedrock limitations to soil depth. In these conditions, sequestration in cropland through appropriate management practices is recommended. Considering the above results, the following experiments of this thesis were focused to take protective measures and CO sequestration in semiarid soils under two of the most representative uses: forest and agricultural. Chapters 4 and 5, explores and discussed the dynamics of soil properties and OC stocks as well as the mechanisms of the accumulation and stabilization of SOC in semiarid areas, after the restoration of a degraded shrubland, with two reforestation techniques. The results showed that the C sequestration, through afforestation of semiarid areas, can be increased by using suitable afforestation techniques. Twenty years after planting, the potential capacity for C sequestration of the afforested ecosystems is far from being saturated and they will continue sequestering C as they reach maturity. In addition, in the afforestation with organic amendment, the increase of labile C pool linked to the changes in microbial activity and fungal community structure, promoted the formation of macroaggregates which acted as the nucleus for the formation of OC-enriched microaggregates inside, mainly in top soil. Chapter 6 is corresponding with an agricultural experimental area, where the impact of the management practices on carbon sequestration and agroecosystem sustainability are studied. The results obtained showed that the greatest increases in the total SOC and OC associated with the aggregates were found with the combination of green manure and reduced tillage (RTG) than no tillage (NT), suggesting that this practice is a good option for OC sequestration since: i) green manure represents a continuous OM input which activates the physical protection of OC through new aggregates formation and physico-chemical stabilization in mineral particles, and ii) minimum tillage is necessary because it favors the incorporation of plant material into deeper layers, promoting the formation of new aggregates in these layers.
    Keywords: Carbono ; Suelos - Análisis ; Ecosistemas ; Ciencias ; 631/635 ; 631
    Source: TDX (Tesis Doctorals en Xarxa)
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  • 10
    Language: English
    In: Biogeosciences, March 15, 2019, Vol.16(5), p.1035
    Description: pThe role of fluvial sedimentary areas as organic carbon sinks remains largely unquantified. Little is known about mechanisms of organic carbon (OC) stabilization in alluvial sediments in semiarid and subhumid catchments where those mechanisms are quite complex because sediments are often redistributed and exposed to a range of environmental conditions in intermittent and perennial fluvial courses within the same catchment. The main goal of this study was to evaluate the contribution of transport and depositional areas as sources or sinks of CO.sub.2 at the catchment scale. We used physical and chemical organic matter fractionation techniques and basal respiration rates in samples representative of the three phases of the erosion process within the catchment: (i) detachment, representing the main sediment sources from forests and agricultural upland soils, as well as fluvial lateral banks; (ii) transport, representing suspended load and bedload in the main channel; and (iii) depositional areas along the channel, downstream in alluvial wedges, and in the reservoir at the outlet of the catchment, representative of medium- and long-term residence deposits, respectively. Our results show that most of the sediments transported and deposited downstream come from agricultural upland soils and fluvial lateral bank sources, where the physicochemical protection of OC is much lower than that of the forest soils, which are less sensitive to erosion. The protection of OC in forest soils and alluvial wedges (medium-term depositional areas) was mainly driven by physical protection (OC within aggregates), while chemical protection of OC (OC adhesion to soil mineral particles) was observed in the fluvial lateral banks. However, in the remaining sediment sources, in sediments during transport, and after deposition in the reservoir (long-term deposit), both mechanisms are equally relevant. Mineralization of the most labile OC (the intra-aggregate particulate organic matter (M.sub.pom) was predominant during transport. Aggregate formation and OC accumulation, mainly associated with macroaggregates and occluded microaggregates within macroaggregates, were predominant in the upper layer of depositional areas. However, OC was highly protected and stabilized at the deeper layers, mainly in the long-term deposits (reservoir), being even more protected than the OC from the most eroding sources (agricultural soils and fluvial lateral banks). Altogether our results show that both medium- and long-term depositional areas can play an important role in erosive areas within catchments, compensating for OC losses from the eroded sources and functioning as C sinks.
    Keywords: Alluvium – Analysis ; Alluvium – Environmental Aspects ; Carbon Sinks – Methods ; Carbon Sinks – Analysis
    ISSN: 1726-4170
    E-ISSN: 17264189
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