Ús i gestió del territori a la mediterrània: implicacions en la matèria orgànica del sòl

Land use and management in Mediterranean ecosystems: implications for soil organic matter. - In the Mediterranean basin, soils have been intensively used to supply food, raw materials and energy. Here we aim to interpret the current status of Mediterranean soils by considering their long history of human use. Mediterranean soils are characterized by their poverty of organic matter and frequent carbonate content. Classical studies indicate that carbonates may favor the retention of soil organic matter. As historic soil data is lacking, we have focused on studying the distribution of organic matter across contrasting land uses. We have seen that soil organic matter poverty mainly affects agricultural soils and pastures (mostly shrublands and grassy swards). In contrast, soil organic matter content in forest soils is very rich, especially in the case of carbonatic soils. However, high levels of organic matter in carbonatic soils are not found in arable or pasture soils. Moreover, pastures contain soil organic matter levels very similar to those of arable soils, particularly in carbonatic soils. In Mediterranean lands the lack of soil structure and the presence of carbonates may jeopardize soil aggradation after the cessation of agricultural practices. In this context soil protection strategies should be adapted to Mediterranean ecosystems in order to better withstand climate change

Land use and management in Mediterranean ecosystems: implications for soil organic matter.

In the Mediterranean basin, soils have been intensively used to supply food, raw materials and energy. Here we aim to interpret the current status of Mediterranean soils by considering their long history of human use. Mediterranean soils are characterized by their poverty of organic matter and frequent carbonate content. Classical studies indicate that carbonates may favor the retention of soil organic matter. As historic soil data is lacking, we have focused on studying the distribution of organic matter across contrasting land uses. We have seen that soil organic matter poverty mainly affects agricultural soils and pastures (mostly shrublands and grassy swards). In contrast, soil organic matter content in forest soils is very rich, especially in the case of carbonatic soils. However, high levels of organic matter in carbonatic soils are not found in arable or pasture soils. Moreover, pastures contain soil organic matter levels very similar to those of arable soils, particularly in carbonatic soils. In Mediterranean lands the lack of soil structure and the presence of carbonates may jeopardize soil aggradation after the cessation of agricultural practices. In this context soil protection strategies should be adapted to Mediterranean ecosystems in order to better withstand climate change

Analysis of soil carbon in Spanish agricultural soils: relevant aspects in relation to the organic farming reconversion in the Mediterranean area

Los niveles de carbono orgánico en suelos agrícolas son especialmente relevantes en los modelos de gestión que se basan en la reserva orgánica de nutrientes. La disminución de materia orgánica que ocurre en los suelos roturados puede en algunos casos determinar la degradación del suelo. Este hecho puede ser especialmente relevante en condiciones climáticas límite (secas y semiáridas). A partir del análisis de una base de datos de suelos españoles se discute la distribución del C en el horizonte superficial de suelo según el clima y según el uso. Para cada área climática, mediante comparación entre suelos forestales y agrícolas se observa que los suelos de clima semiárido presentan una mayor resistencia a la pérdida de C y una menor resiliencia que los suelos de climas más húmedos. Este hecho nos hace pensar que los suelos semiáridos pueden estar cerca de los umbrales de degradación y que por lo tanto su gestión debería evitar les pérdidas de materia orgánica.Organic carbon levels in agricultural soils are specially relevant in the management models based on the organic reserve of the soil. Losses of soil organic matter that occur associated to tillage practices can enhance, in some cases, soil degradation. This fact may be specially relevant in dry and semiarid climates. By analysing a soil data base of the Spanish forest and agricultural soils we discuss the distribution of C in the soil surface horizon across climates and land uses. In each climatic area, by comparing forest with agricultural soils we found that soils in semiarid climate show greater resistance to soil C losses and lower resilience than soils of wetter climates. This fact suggest that semiarid soils can be at or near soil degradation thresholds and thus its management should avoid any losses of soil organic matter.Este trabajo ha sido posible gracias a un convenio establecido entre la Dirección General de Evaluación Ambiental del Ministerio de Medio Ambiente y la Universidad de Barcelona

Crop yield, weed infestation and soil fertility responses to contrasted ploughing intensity and manure additions in a Mediterranean organic crop rotation

Conservation agriculture and organic farming are two alternative strategies that aim to improve soil quality and fertility in arable cropping systems through the deployment of different practices, that are rarely combined. While conservation agriculture practices include reducing tillage intensity and maintaining soil cover all year round to prevent soil erosion, organic farming focuses on nutrient recycling, using farmyard manure and green manure to enhance soil quality. However, these practices are not free from side-effects, such as increasing weed infestation or limited nutrient availability. Therefore it is necessary to explore the sustainability of their combination under local environmental constraints. The objectives of this study were to evaluate the effects of tillage type (mouldboard vs. chisel ploughing), fertilization and green manure on soil parameters (SOC, N, bulk density, carbon stocks, and soil microbial biomass Cmic and Nmic), weed abundance and crop yields in a four-year rotation of spelt, chickpea, winter wheat and lentil in the Mediterranean region (Catalonia, Spain). Tillage and green manure did not affect crop yields or weed biomass, although during the last year of the experiment, plots with mouldboard ploughing had less weed biomass and higher lentil biomass. Fertilization was the most important factor, increasing the cereal yields, SOC, N and soil microbial biomass (Cmic and Nmic) content of the soil. However, fertilization did not favour chickpea and lentil crops because weed competition limited legume crop growth. Overall, there was a loss of SOC and a reduction of carbon stocks over the four years of the trial in the soil because of the deep soil tillage (25 cm) and low crop productivity irrespective of tillage type. In contrast, N content increased in all of the plots and was enhanced by fertilization. The use of chisel plough stratified the distribution of SOC and N in the surface layers (0-10 cm). Both Cmic and Cmic/SOC ratio increased in fertilized treatments, suggesting an increased lability of SOC. The application of more stabilized organic matter may be a better practice to build up soil organic matter and to maintain crop yields in organic farming systems

Impact of olive saplings and organic amendments on soil microbial communities and effects of mineral fertilization

Plant communities and fertilization may have an impact on soil microbiome. Most commercial olive trees are minerally fertilized, while this practice is being replaced by the use of organic amendments. Organic amendments can both fertilize and promote plant growth-promoting organisms. Our aims were (i) to describe the changes in soil bacterial and fungal communities induced by the presence of young olive trees and their interaction with organic amendments and (ii) to compare the effects of mineral and organic fertilization. We set up two parallel experiments in pots using a previously homogenized soil collected from a commercial olive orchard: in the first one, we grew olive saplings in unamended and organically amended soils with two distinct composts and compared these two soils incubated without a plant, while in the second experiment, we comparatively tested the effects of organic and mineral fertilization. OTUs and the relative abundances of bacterial and fungal genera and phyla were analyzed by 16S rRNA and ITS1 gene amplicon using high-throughput sequencing. Basal respiration and substrate-induced respiration were measured by MicroRespTM. The effects of the different treatments were analyzed in all phyla and in the 100 most abundant genera. The presence of olive saplings increased substrate-induced respiration and bacterial and fungal richness and diversity. Organic amendments greatly affected both bacterial and fungal phyla and increased bacterial richness while not affecting fungal richness. Mineral fertilization increased the relative abundance of the less metabolically active bacterial phyla (Actinobacteria and Firmicutes), while it reduced the most metabolically active phylum, Bacteroidetes. Mineral fertilization increased the relative abundance of three N2-fixing Actinobacteria genera, while organic fertilization only increased one genus of Proteobacteria. In organically and minerally fertilized soils, high basal respiration rates were associated with low fungal diversity. Basidiomycota and Chytridiomycota relative abundances positively correlated with basal respiration and substrate-induced respiration, while Ascomycota correlated negatively. Indeed, the Ascomycota phyla comprised most of the fungal genera decreased by organic amendments. The symbiotrophic phylum Glomeromycota did not correlate with any of the C sources. The relative abundance of this phylum was promoted by the presence of plants but decreased when amending soils with composts

La restauración ecológica aplicada a la minería a cielo abierto en Cataluña

En la minería a cielo abierto, la revegetación es el objetivo principal de las tareas de restauración ecológica y puede evaluarse desde diferentes enfoques. El aspecto paisajístico ha sido hasta la fecha el más ampliamente valorado y frecuentemente suele asimilarse a la presencia de vegetación que disminuye el impacto visual de estas zonas.La frase 'está verde' simboliza y resume todo un conjunto de prioridades y una primera etapa de implementación de la ley 12/1981 de la legislación catalana.De hecho, naturalizar los taludes resultantes del cese de la extracción de recursos minerales no es una tarea fácil. El tipo de vegetación obtenido difiere en muchos casos de la vegetación de los sistemas natural es del entorno y genera una disfunción en el contexto paisajístico y ecológico [...]

On the distinctive features of Mediterranean soils

En aquest article es revisen els components de la fertilitat dels sòls mediterranis i es discuteixen les seves característiques generals, així com la suposada oligotrofia que sovint se'ls ha atribuït. La tipologia d 'aquests sòls i els cicles del N i P presenten alguns trets comuns que vénen de tenninats per trobar-se en un règim de clima mediterrani, tanmateix existeixen diferències remarcables que es relacionen, sobretot, amb el tipus de roca mare i que expliquen les diferències sovint atribuïdes als sòls de les cinc regions mediterrànies. La matèria orgànica i el cicle del nitrogen són especialment actius en els sòls mediterranis, la qual cosa es relaciona amb temperatures característicament altes. El contingut de Pi la seva disponibilitat presenten una elevada variabilitat originada pels diferents tipus de substrat litològic i grau de meteorització. Els incendis sempre comporten pèrdues netes de nutrients per al sistema i la seva recuperació pot requerir períodes llargs de temps. Tanmateix, immediatament després de l 'incendi, acostuma a haver-hi un increment temporal de nutrients disponibles que pennet una regeneració eficient de la vegetació durant un període curt de temps. En àreas fràgils de la Conca Mediterrània, sovint prèviament modificades antròpicament, el foc pot desencadenar una forta degradació dels sòls.Soil fertility components in Mediterranean soils are reviewed to discuss their possible com mon general features and the oligotrophy often attributed to these soils. Mediterranean soils typology and N and P cycling show some similar overall trends owing to the common climatic characteristics, but also considerable differences especially related to the parent bedrock. Differences often attributed to the soils from the five Mediterranean regions of the world can be mostly explained from the above mentioned factors. Soil organic matter and nitrogen cycling are especially active in the Mediterranean soils, in relation to the relatively high characteristic temperatures. P content and availability show considerable variation owing to differences in parent material and degree of soil weathering. Wildfires always produce nutrient losses to the ecosystem that could require long periods of time to recover. However, the enhanced fertility commonly produced just after the fire allows an efficient short-term regeneration of the vegetation. The human impacts on the ecosystems such as fires and cultivation/abandonment, that have been especially relevant in the Mediterranean Basin for centuries, can introduce strong soil degradation in fragile areas

Crop yield, weed infestation and soil fertility responses to contrasted ploughing intensity and manure additions in a Mediterranean organic crop rotation

Conservation agriculture and organic farming are two alternative strategies that aim to improve soil quality and fertility in arable cropping systems through reducing tillage intensity, maintaining soil cover and increasing nutrient recycling, using farmyard and green manures. However, these practices can increase weed infestation or decrease nutrient availability. The objectives of this study were to evaluate the effects of tillage type (mouldboard vs. chisel ploughing), fertilization and green manure on soil parameters (SOC, N, bulk density, carbon stocks, and soil microbial biomass Cmic and Nmic), weed abundance and crop yields in a four-year rotation of spelt, chickpea, winter wheat and lentil in the Mediterranean region (Catalonia, Spain). Tillage and green manure did not affect crop yields or weed biomass, although during the last year of the experiment, plots with mouldboard ploughing had less weed biomass and higher lentil biomass. Fertilization was the most important factor, increasing the cereal yields, SOC, N and soil microbial biomass (Cmic and Nmic) content of the soil. However, fertilization did not favour chickpea and lentil crops because weed competition limited legume crop growth. Overall, there was a loss of SOC and a reduction of carbon stocks over the four years of the trial in the soil because of the deep soil tillage (25 cm) and low crop productivity irrespective of tillage type. In contrast, N content increased in all of the plots and was enhanced by fertilization. The use of chisel plough stratified the distribution of SOC and N in the surface layers (0-10 cm). Both Cmic and Cmic/SOC ratio increased in fertilized treatments, suggesting an increased lability of SOC. The application of more stabilized organic matter may be a better practice to build up soil organic matter and to maintain crop yields in organic farming systems

Sweet Potato Is Not Simply an Abundant Food Crop: A Comprehensive Review of Its Phytochemical Constituents, Biological Activities, and the Effects of Processing

Nowadays, sweet potato (Ipomoea batata L.; Lam.) is considered a very interesting nutritive food because it is rich in complex carbohydrates, but as a tubercle, contains high amounts of healthpromoting secondary metabolites. The aim of this review is to summarize the most recently published information on this root vegetable, focusing on its bioactive phytochemical constituents, potential effects on health, and the impact of processing technologies. Sweet potato is considered an excellent source of dietary carotenoids, and polysaccharides, whose health benefits include antioxidant, antiinflammatory and hepatoprotective activity, cardiovascular protection, anticancer properties and improvement in neurological and memory capacity, metabolic disorders, and intestinal barrier function. Moreover, the purple sweet potato, due to its high anthocyanin content, represents a unique food option for consumers, as well as a potential source of functional ingredients for healthy food products. In this context, the effects of commercial processing and domestic cooking techniques on sweet potato bioactive compounds require further study to understand how to minimize their loss

The Effects of Differentiated Organic Fertilization on Tomato Production and Phenolic Content in Traditional and High-Yielding Varieties

The challenge of sustainable agriculture is to increase yields and obtain higher quality products. Increased antioxidant compounds such as polyphenols in harvest products may be an added value for sustainable agriculture. The aim of the present study was to investigate whether three organic fertilization treatments with different levels of carbon and nitrogen, i.e., N-rich, N-rich+C, and N-poor+C, affected the phenolic content of different tomato varieties. The examined parameters were productivity, plant nutritional status, δ13C, and tomato phenolic content as an indication of the antioxidant capacity. The best production was obtained with 'Cornabel', a high-yielding Pebroter variety. The total phenolic content was highest in the traditional 'Cuban Pepper' variety regardless of treatment, while naringenin levels were high in all the Pebroter varieties. In N-poor+C fertilized plants, a lower N-NO3 content in leaves was correlated with higher levels of total polyphenols in the fruit. The high-water stress suffered by Montserrat varieties coincided with a low total phenolic content in the tomatoes. In conclusion, organic fertilization with reduced N did not influence the tomato yield but positively affected phenolic compound levels in varieties less sensitive to water stress