Samples of a Mediterranean forest soil were exposed in a muffle furnace to seven temperatures (10... more Samples of a Mediterranean forest soil were exposed in a muffle furnace to seven temperatures (100–700°C) for 15 min to simulate different fire intensities. Heated soils were incubated for 100 days after re-inoculation with fresh unheated soil. Immediately after heating, the extractable organic C increased with the heating temperature, reaching a maximum at 400°C. This increase in extractable organic C and nutrients in soils heated below 400°C allowed a rapid recolonization of bacteria, increasing the basal respiration. During the 100-day incubation, the cumulative values of basal respiration and carbon mineralization rates generally followed a double exponential equation in unheated and heated samples. Heating at 200°C caused a reduction of 99.6% for fungi (measured as culturable fungal propagules), which showed lower recolonization capacity than that of bacteria. Heating also caused a decrease in the organic C content of the soils, especially for the highest temperatures. As a con...
Alkaline soils are considered much less prone to developing water repellency induced by fire than... more Alkaline soils are considered much less prone to developing water repellency induced by fire than acidic soils. Here we report on the persistence of water repellency present in calcareous soils immediately after wildfires in 10 burned areas in SE Spain, its distribution in different aggregate size fractions (<2, 2–1, 1–0.5, 0.5–0.25 and <0.25 mm) and on results from aggregate stability tests.
Previous studies have shown that long-term irrigation with wastewater can lead to the development... more Previous studies have shown that long-term irrigation with wastewater can lead to the development of soil water repellency. Little is known about the longevity of this effect. Here we address this research gap by examining the effect of long-term (~ 20 years) use of low-quality wastewater for disposal purposes, followed by 6 years of ‘recovery’ with no irrigation, on the wettability of calcareous sandy soil (Xerofluvent) under a Populus alba tree stand used as a “green filter” in SE Spain. Water repellency (WR) and soil organic matter content (SOM) were determined for 120 air-dry samples from the plot and 80 control samples from adjacent and otherwise similar non-irrigated areas. To account for plot micro-topography 40 samples each were taken from ridges (R; 0–5 cm depth), furrows (F; 0–5 cm), and furrows at depth (FD; 5–10 cm). The controls included 40 samples each (0–5 cm depth) from unvegetated and unploughed soil, and from soil under the P. alba plantation.All control samples were non-repellent whereas at the irrigated plot, water repellency was present for 48, 95 and 93% of ridge, furrow and furrow-depth samples respectively. WR and SOM was strongly correlated within the whole sample population (R2 = 0.623**) and within two sample groups (R: R2 = 0.783**; FD: R2 = 0.424**), but weakly within F samples (R2 = 0.072 n.s.). The latter showed the highest frequency and persistence (WDPT) of WR, indicating that not only quantity of SOM is controlling WR. Exploratory kaolinite clay additions (0.5–8%) to samples substantially reduced WR even at the lowest concentration, indicating that this could be a promising amelioration treatment for the WR in the soils investigated here.We conclude that for the conditions studied here (i) long-term use with poor-quality wastewater for disposal had led to the development of soil WR, (ii) a 6-year period of ‘recovery’ (i.e. non-irrigation) was insufficient to eliminate the induced WR, and (iii) kaolinite addition could be a promising amelioration treatment for these sandy soils.► Long-term application of wastewater with poor-quality had led to the development of soil WR. ► A 6-year period of ‘recovery’ has been insufficient to eliminate the induced WR. ► Kaolinite addition appears to be effective as an amelioration treatment for these sandy soils.
Flood irrigated citrus orchard abandonment in eastern Spain is due to socio-economic changes and ... more Flood irrigated citrus orchard abandonment in eastern Spain is due to socio-economic changes and the small size of the farms. By means of a cylinder infiltrometer and measurements of soil organic matter we conclude that land abandonment favours an increase in total carbon and infiltration rates. The recovery showed a crisis in the first year after abandonment, when the vegetation did not recover and the soil was affected by a surface crust. Although the abandoned orchards did not receive fertilizers or irrigation, the abandonment is positive for recovery of organic matter and infiltration rates.
Shortage of water is one of the most important environmental problem in the Mediterranean areas t... more Shortage of water is one of the most important environmental problem in the Mediterranean areas that implicates the search for strategies for saving good quality water. The use of treated waste water for the irrigation of agricultural land can be a good solution for this problem because it reduces the utilization of fresh water and potentially could improve soil key parameters, but can modify physical-chemical and biological properties of the same. The aim of this work was to study the effect of long-term irrigation with treated waste water on microbial diversity, mainly arbuscular mycorrhizal fungi (AMF) of the soil and other properties related with the microbial community. The experiment was developed in an agricultural area with Citrus orchard, located in Alicante in the southeast Spain. Here, we tested whether the communities of AMF as well as soil microbial properties were affected by irrigation with water coming from sewage treatment plant during 40 years in a soil. To carry o...
El presente trabajo muestra una primera aproximación experimental para el seguimiento del proceso... more El presente trabajo muestra una primera aproximación experimental para el seguimiento del proceso de compostaje a gran escala de un lodo de depuradora, mediante el empleo de radiometría visible e infrarrojo cercano (VNIR).
ABSTRACT We investigated the diversity of arbuscular mycorrhizal fungi (AMF) in roots of Prunus p... more ABSTRACT We investigated the diversity of arbuscular mycorrhizal fungi (AMF) in roots of Prunus persica under two fertilization treatments (CF: consisted of application of chicken manure (1400 kg.ha-1), urea (140 kg.ha-1), complex fertilizer 12-12-17/2 (280 kg.ha-1), and potassium sulfate (40 kg.ha-1) and IF: consisted of application of urea (140 kg.ha-1), complex fertilizer 12-12-17/2 (400 kg.ha-1) and potassium sulfate (70 kg.ha-1)) combined with integrated pest management (IM) or chemical pest management (CM), in a tropical agroecosystem in the north of Venezuela. Our goal was to ascertain how different fertilizers/pest management can modify the AMF diversity colonizing P. persica roots as an important step towards sustainable soil use and therefore protection of biodiversity. The AM fungal small-subunit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty-one different phylotypes were identified, which were grouped in five families: Glomeraceae, Paraglomeraceae, Acaulosporaceae, Gigasporaceae and Archaeosporaceae. Sixteen of these sequence groups belonged to the genus Glomus, two to Paraglomus, one to Acaulospora, one to Scutellospora and one to Archaeospora. A different distribution of the AMF phylotypes as consequence of the difference between treatments was observed. Thus, the AMF communities of tree roots in the (IF+CM) treatment had the lowest diversity (H'=1.78) with the lowest total number of AMF sequence types (9). The trees from both (CF+IM) and (IF+IM) treatments had similar AMF diversity (H'?2.00); while the treatment (CF+CM) yielded the highest number of different AMF sequence types (17) and showed the highest diversity index (H'=2.69). In conclusion, the crop management including combination of organic and inorganic fertilization and chemical pest control appears to be the most suitable strategy with respect to reactivate the AMF diversity in the roots of this crop and thus, the agricultural and environmental sustainability in the agroecosystem.
ABSTRACT Land abandonment throughout the twentieth century led to an intense landscape transforma... more ABSTRACT Land abandonment throughout the twentieth century led to an intense landscape transformation in the mountain areas of the Iberian Peninsula. In some cases, and after 50 years of abandonment, agriculture returned with the development of commercial farms and the intensification of the agrarian activities. In the Easter Iberian Peninsula, following the abandonment of olive groves, vineyards and cereals during the 50's, has been in the past two decades the expansion of intensive citrus production on sloping terrain. Geomorphological transects and simulated rainfall experiments have quantified the impact of traditional rainfed cultivation of the 50's, abandonment, and the intensification of farming on the processes and landforms of erosion on the northern slopes of the Serra Grossa, south of the province of Valencia. It was found that the citrus groves have the highest number of rills and gullies. These erosive morphologies were not in the traditional crop tillage, and when they formed in the abandoned fields were soon controlled by the growth of vegetation. The abandonment of the crops reduced the soil losses, but the intensification of the agriculture with the citrus production has accelerated the soil erosion rates that exceed by several orders of magnitude (x4) the soil erosion rates measured during the abandonment and multiply by 17 the quantified traditional rainfed agriculture soil losses. Tillage of traditional rainfed orchards reduced runoff, but increased the concentration of sediments of the surface wash.
Samples of a Mediterranean forest soil were exposed in a muffle furnace to seven temperatures (10... more Samples of a Mediterranean forest soil were exposed in a muffle furnace to seven temperatures (100–700°C) for 15 min to simulate different fire intensities. Heated soils were incubated for 100 days after re-inoculation with fresh unheated soil. Immediately after heating, the extractable organic C increased with the heating temperature, reaching a maximum at 400°C. This increase in extractable organic C and nutrients in soils heated below 400°C allowed a rapid recolonization of bacteria, increasing the basal respiration. During the 100-day incubation, the cumulative values of basal respiration and carbon mineralization rates generally followed a double exponential equation in unheated and heated samples. Heating at 200°C caused a reduction of 99.6% for fungi (measured as culturable fungal propagules), which showed lower recolonization capacity than that of bacteria. Heating also caused a decrease in the organic C content of the soils, especially for the highest temperatures. As a con...
Alkaline soils are considered much less prone to developing water repellency induced by fire than... more Alkaline soils are considered much less prone to developing water repellency induced by fire than acidic soils. Here we report on the persistence of water repellency present in calcareous soils immediately after wildfires in 10 burned areas in SE Spain, its distribution in different aggregate size fractions (<2, 2–1, 1–0.5, 0.5–0.25 and <0.25 mm) and on results from aggregate stability tests.
Previous studies have shown that long-term irrigation with wastewater can lead to the development... more Previous studies have shown that long-term irrigation with wastewater can lead to the development of soil water repellency. Little is known about the longevity of this effect. Here we address this research gap by examining the effect of long-term (~ 20 years) use of low-quality wastewater for disposal purposes, followed by 6 years of ‘recovery’ with no irrigation, on the wettability of calcareous sandy soil (Xerofluvent) under a Populus alba tree stand used as a “green filter” in SE Spain. Water repellency (WR) and soil organic matter content (SOM) were determined for 120 air-dry samples from the plot and 80 control samples from adjacent and otherwise similar non-irrigated areas. To account for plot micro-topography 40 samples each were taken from ridges (R; 0–5 cm depth), furrows (F; 0–5 cm), and furrows at depth (FD; 5–10 cm). The controls included 40 samples each (0–5 cm depth) from unvegetated and unploughed soil, and from soil under the P. alba plantation.All control samples were non-repellent whereas at the irrigated plot, water repellency was present for 48, 95 and 93% of ridge, furrow and furrow-depth samples respectively. WR and SOM was strongly correlated within the whole sample population (R2 = 0.623**) and within two sample groups (R: R2 = 0.783**; FD: R2 = 0.424**), but weakly within F samples (R2 = 0.072 n.s.). The latter showed the highest frequency and persistence (WDPT) of WR, indicating that not only quantity of SOM is controlling WR. Exploratory kaolinite clay additions (0.5–8%) to samples substantially reduced WR even at the lowest concentration, indicating that this could be a promising amelioration treatment for the WR in the soils investigated here.We conclude that for the conditions studied here (i) long-term use with poor-quality wastewater for disposal had led to the development of soil WR, (ii) a 6-year period of ‘recovery’ (i.e. non-irrigation) was insufficient to eliminate the induced WR, and (iii) kaolinite addition could be a promising amelioration treatment for these sandy soils.► Long-term application of wastewater with poor-quality had led to the development of soil WR. ► A 6-year period of ‘recovery’ has been insufficient to eliminate the induced WR. ► Kaolinite addition appears to be effective as an amelioration treatment for these sandy soils.
Flood irrigated citrus orchard abandonment in eastern Spain is due to socio-economic changes and ... more Flood irrigated citrus orchard abandonment in eastern Spain is due to socio-economic changes and the small size of the farms. By means of a cylinder infiltrometer and measurements of soil organic matter we conclude that land abandonment favours an increase in total carbon and infiltration rates. The recovery showed a crisis in the first year after abandonment, when the vegetation did not recover and the soil was affected by a surface crust. Although the abandoned orchards did not receive fertilizers or irrigation, the abandonment is positive for recovery of organic matter and infiltration rates.
Shortage of water is one of the most important environmental problem in the Mediterranean areas t... more Shortage of water is one of the most important environmental problem in the Mediterranean areas that implicates the search for strategies for saving good quality water. The use of treated waste water for the irrigation of agricultural land can be a good solution for this problem because it reduces the utilization of fresh water and potentially could improve soil key parameters, but can modify physical-chemical and biological properties of the same. The aim of this work was to study the effect of long-term irrigation with treated waste water on microbial diversity, mainly arbuscular mycorrhizal fungi (AMF) of the soil and other properties related with the microbial community. The experiment was developed in an agricultural area with Citrus orchard, located in Alicante in the southeast Spain. Here, we tested whether the communities of AMF as well as soil microbial properties were affected by irrigation with water coming from sewage treatment plant during 40 years in a soil. To carry o...
El presente trabajo muestra una primera aproximación experimental para el seguimiento del proceso... more El presente trabajo muestra una primera aproximación experimental para el seguimiento del proceso de compostaje a gran escala de un lodo de depuradora, mediante el empleo de radiometría visible e infrarrojo cercano (VNIR).
ABSTRACT We investigated the diversity of arbuscular mycorrhizal fungi (AMF) in roots of Prunus p... more ABSTRACT We investigated the diversity of arbuscular mycorrhizal fungi (AMF) in roots of Prunus persica under two fertilization treatments (CF: consisted of application of chicken manure (1400 kg.ha-1), urea (140 kg.ha-1), complex fertilizer 12-12-17/2 (280 kg.ha-1), and potassium sulfate (40 kg.ha-1) and IF: consisted of application of urea (140 kg.ha-1), complex fertilizer 12-12-17/2 (400 kg.ha-1) and potassium sulfate (70 kg.ha-1)) combined with integrated pest management (IM) or chemical pest management (CM), in a tropical agroecosystem in the north of Venezuela. Our goal was to ascertain how different fertilizers/pest management can modify the AMF diversity colonizing P. persica roots as an important step towards sustainable soil use and therefore protection of biodiversity. The AM fungal small-subunit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty-one different phylotypes were identified, which were grouped in five families: Glomeraceae, Paraglomeraceae, Acaulosporaceae, Gigasporaceae and Archaeosporaceae. Sixteen of these sequence groups belonged to the genus Glomus, two to Paraglomus, one to Acaulospora, one to Scutellospora and one to Archaeospora. A different distribution of the AMF phylotypes as consequence of the difference between treatments was observed. Thus, the AMF communities of tree roots in the (IF+CM) treatment had the lowest diversity (H'=1.78) with the lowest total number of AMF sequence types (9). The trees from both (CF+IM) and (IF+IM) treatments had similar AMF diversity (H'?2.00); while the treatment (CF+CM) yielded the highest number of different AMF sequence types (17) and showed the highest diversity index (H'=2.69). In conclusion, the crop management including combination of organic and inorganic fertilization and chemical pest control appears to be the most suitable strategy with respect to reactivate the AMF diversity in the roots of this crop and thus, the agricultural and environmental sustainability in the agroecosystem.
ABSTRACT Land abandonment throughout the twentieth century led to an intense landscape transforma... more ABSTRACT Land abandonment throughout the twentieth century led to an intense landscape transformation in the mountain areas of the Iberian Peninsula. In some cases, and after 50 years of abandonment, agriculture returned with the development of commercial farms and the intensification of the agrarian activities. In the Easter Iberian Peninsula, following the abandonment of olive groves, vineyards and cereals during the 50's, has been in the past two decades the expansion of intensive citrus production on sloping terrain. Geomorphological transects and simulated rainfall experiments have quantified the impact of traditional rainfed cultivation of the 50's, abandonment, and the intensification of farming on the processes and landforms of erosion on the northern slopes of the Serra Grossa, south of the province of Valencia. It was found that the citrus groves have the highest number of rills and gullies. These erosive morphologies were not in the traditional crop tillage, and when they formed in the abandoned fields were soon controlled by the growth of vegetation. The abandonment of the crops reduced the soil losses, but the intensification of the agriculture with the citrus production has accelerated the soil erosion rates that exceed by several orders of magnitude (x4) the soil erosion rates measured during the abandonment and multiply by 17 the quantified traditional rainfed agriculture soil losses. Tillage of traditional rainfed orchards reduced runoff, but increased the concentration of sediments of the surface wash.
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