Search results for "Fishe"
showing 10 items of 2001 documents
Variability of near-surface saturated hydraulic conductivity for the clay soils of a small Sicilian basin
2019
Abstract Proper characterization of saturated hydraulic conductivity, Ks, of clay soils in a hillslope or a basin is still a challenge for soil science. In this investigation, the clay soils of the Maganoce (Sicily, Italy) basin were sampled at 19 sampling sites by the BEST procedure of soil hydraulic characterization. More OM implied less compact conditions (decreasing dry soil bulk density; coefficient of determination, R2 = 0.67), more stability to water of the soil aggregates (increasing water stable aggregates; R2 = 0.83) and, consequently, higher Ks values (R2 = 0.54). Variability of Ks was lower in the steeper zones of the basin than in the flatter ones. A comparison with the Ks data…
The effect of soil on human health: an overview
2018
Soil has a considerable effect on human health, whether those effects are positive or negative, direct or indirect. Soil is an important source of nutrients in our food supply and medicines such as antibiotics. However, nutrient imbalances and the presence of human pathogens in the soil biological community can cause negative effects on health. There are also many locations where various elements or chemical compounds are found in soil at toxic levels, because of either natural conditions or anthropogenic activities. The soil of urban environments has received increased attention in the last few years, and they too pose a number of human health questions and challenges. Concepts such as soi…
Changes in soil redox potential in response to flood irrigation with waste water in central Mexico
2017
Irrigation with untreated sewage water adds fresh organic matter to the soil. When it is applied by flooding, as in the Mezquital Valley of Mexico, many of the pores in the soil become temporarily waterlogged and depleted of oxygen, and reduction generates nitrous oxide (N2O) and methane (CH4). We monitored the redox potential, Eh, in the soil at two sites in the Mezquital Valley to discover whether the short-term gaseous emissions matched the changes in Eh. One site is irrigated periodically by flooding with waste water and has alfalfa, rye grass and maize grown in succession; the other site grows maize with water from summer rain only. Each electrode buried in the soil for the purpose pro…
Decomposer animal communities in forest soil along heavy metal pollution gradient
1996
Responses of soil decomposer animals to heavy metal contamination and to concomitant changes in organic matter quality and quantity and in soil microbial biomasses have been studied along a pollution gradient from a Cu-Ni smelter. Samples have been taken separately for nematodes, enchytraeids and microarthropods 0.5, 2 and 8 km from the smelter. Special attention has been paid to the changes in the collembolan fauna. The sampling sites have been located in homogeneous Scots pine ( Pinus sylvestris) forests with podsolic soil profiles. In addition, an experiment has been carried out in which intact soil cores have been transferred in mesh baskets between the sites 2 and 8 km from the smelter…
Reduction of the frequency of herbaceous roots as an effect of soil compaction induced by heavy grazing in rangelands of SW Spain
2017
Rangelands in SW Spain constitute the most extensive ranching system on the Iberian Peninsula. During the last few decades, a significant increase in livestock numbers, along with a progressive substitution of cattle for sheep, have led to land degradation processes such as the reduction of grass cover and increased soil compaction in heavily grazed areas. Nevertheless, a better understanding of how soil compaction affects grass production is still needed. In this study, some of the effects of soil compaction due to heavy grazing are analysed, mainly the reduction of the frequency of herbaceous roots and its relationships with bulk density and soil penetration resistance. The study was carr…
Patterns of earthworm, enchytraeid and nematode diversity and community structure in urban soils of different ages
2016
Annelids (Lumbricidae and Enchytraeidae) and nematodes are common soil organisms and play important roles in organic matter decomposition, nutrient cycling and creation of soil structure and porosity. However, these three groups have rarely been studied together and only few studies exist for urban soils. We studied the diversity and community composition of annelids and nematodes in soils spanning more than two centuries of urban soil development in Neuchâtel (Switzerland) and assessed the relationships 1) among these three groups and 2) between each group and environmental (physical, chemical and functional) characteristics of soils and soil age. While the groups of environmental variable…
Effect of Cd-containing wood ash on the microflora of coniferous forest humus
2000
The use of wood ash in forestry has been questioned because the cadmium (Cd) concentration of ash, which varies between 1 and 20 mg kg(-1) ash, exceeds the level allowed for fertilizers (3 mg kg(-1)) used in agriculture. To investigate the combined and separated effects of Cd and ash on the forest humus microflora, pumice or wood ash, spiked with a water-soluble (CdCl(2)) or -insoluble (CdO) form of Cd at three levels (0, 400 and 1000 mg kg(-1)), were applied at a fertilization level of 5000 kg ha(-1) in a laboratory microcosm study. The trial consisted of 60 microcosms (five replications per treatment), which were incubated in darkness at +20 degrees C and a constant relative air humidity …
Abundance and activity of nitrate reducers in an arable soil are more affected by temporal variation and soil depth than by elevated atmospheric [CO2]
2011
Elevated atmospheric carbon dioxide concentrations ([CO2]) might change the abundance and the function of soil microorganisms in the depth profile of agricultural soils by plant-mediated reactions. The seasonal pattern of abundance and activity of nitrate-reducing bacteria was studied in a Mini-FACE experiment planted with oilseed rape (Brassica napus). Three depths (0–10, 10–20 and 20–30 cm) were sampled. Analyses of the abundances of total (16S rRNA gene) and nitrate-reducing bacteria (narG, napA) revealed strong influences of sampling date and depth, but no [CO2] effects. Abundance and activity of nitrate reducers were higher in the top soil layer and decreased with depth but were not re…
A STUDY ON THE POSSIBLE EFFECT OF TWO CRAYFISH SPECIES ON EPILITHIC ALGAE IN A MOUNTAIN STREAM FROM CENTRAL SPAIN
2006
The effects on epilithic algae of increasing densities of two crayfish species, Austropotamobius italicus and Pacifastacus leniusculus, the latter recently introduced in Spain, have been monitored using riverine enclosures, within a large experimental study on crayfish-macrobenthos interactions in a mountain stream. A 3-month test was carried out for each species using crayfish densities comprising between 0-5 individuals/m2 kept in 1-m2 enclosures. Epilithon was sampled periodically within the enclosures and chlorophyll a, b and c were measured by spectrophotometry. Neither statistically significant positive nor negative effects were observed on algal abundance (Chl concentrations) during …
From sustainability to sustainable development: the role of food banks in food security in Uganda : a case study of the hunger project food bank - Mb…
2014
Master thesis in development management - University of Agder 2014 The purpose of this study is to identify the role the food bank plays for food security, sustainable livelihoods and building resilience to climate change among smallholder farmers in Uganda. The aim is to investigate how the food bank in Uganda operates in relation to food security and smallholder farmers. Much of the studies on food banks reveal that food banks are merely institutions that offer emergency food supplies to the hungry and are not agencies aiming at food security. These studies have, however, been based on the context of developed countries and no study has been conducted to establish the role of food banks i…