Search results for "soil"
showing 10 items of 3493 documents
Effect of ramp size and sample spinning speed on CPMAS 13C NMR spectra of soil organic matter
2011
Abstract Cross polarization (CP) magic angle spinning (MAS) 13C NMR spectroscopy is a solid state NMR technique widely applied to study the chemical composition of natural organic matter. In high magnetic fields (>7 T), fast sample spinning is required in order to reduce the influence of spinning sidebands underlying other chemical shift regions. As the spinning speed increases, the Hartmann–Hahn matching profiles break down into a series of narrow matching bands. In order to account for this instability variable amplitude cross polarization techniques (e.g. VACP, ramp-CP) have been developed. In the present study, we experimentally verified the stability of the Hartmann–Hahn condition unde…
Leaching of n and c from birch leaf litter and raw humus with special emphasis on the influence of soil fauna
1988
Abstract To examine the role of a community of soil animals in N-mineralization and C fluxes in dead organic matter, we established a microcosm system with substrates composed of: (a) birch leaf litter; (b) raw coniferous humus; and (c) litter on humus. Every 3–4 wks the substrates were irrigated with distilled water, and the amounts of NO5-N, NH4-N, total-N and total-C (as well as humic substances at one recording) in the leachates were analyzed. At the end of the experiment, water-soluble and exchangeable forms of N were measured in the test materials. The differences in the release of N were clear both between the replicates with and without soil animals and between the different forms o…
Reversing agriculture from intensive to sustainable improves soil quality in a semiarid South Italian soil
2010
Intensive agriculture (IA) is widespread in South Italy, although it requires frequent tillage, large amounts of fertilizers and irrigation water. We have assessed the efficacy of reversing IA to sustainable agriculture (SA) in recovering quality of a typical South Italy soil (Lithic Haploxeralf). This reversion, lasting from 2000 to 2007, replaced 75% of nutrients formerly supplied inorganically by farmyard manuring and reduced the tillage frequency. Several chemical and biochemical properties, functionally related to C and N mineralisation–immobilisation processes and to P and S nutrient cycles, were monitored annually from 2005 to 2007 in the spring. Reversing IA to SA decreased soil bul…
Humic substances along the profile of two Typic Haploxerert
2002
Abstract In Vertisols, organic matter contributes to soil colour by formation of organo-mineral complexes and affects morphological, physico-chemical, biological and biochemical properties. Turbation may affect the chemical and structural composition of the most stabilised fractions of soil organic matter (SOM), i.e., humic substances (HS). The objectives of this study were to: (1) characterise SOM in two Vertisols (V1 and V2) developed under Mediterranean climate in Italy, using some HS characteristics as indicators of SOM turnover in Vertisols, and (2) explore possible differences related to the pedomorphologic conditions of the area under which two soils have formed. SOM evolution along …
Temporal fatty acid profiles of human decomposition fluid in soil
2017
Abstract We studied the changes in concentration and relative abundance of human-derived fatty acids (FAs) in soil over a period of one year. The study is based on analysis of soil underneath a human body that lay on the soil surface for 18 days before it was discovered. Soil samples were taken when the body was removed, and also 358 days later. Large amounts of the total FA concentration at the start of the measurement period were still present one year after the removal of the body. The FA profile suggested that extensive saturated FA reduction occurred during the first 18 days after deposition. 10-Hydroxystearic acid and FA salts, which are characteristic of adipocere, were abundant in a…
Changes in soil microbial activity and physicochemical properties in agricultural soils in Eastern Spain
2015
Agricultural land management greatly affects soil properties. Microbial soil communities are the most sensitive and rapid indicators of perturbations in land use and soil enzyme activities are sensitive biological indicators of the effects of soil management practices. Citrus orchards frequently have degraded soils and this paper evaluates how land management in citrus orchards can improve soil quality. A field experiment was performed in an orchard of orange trees (<em>Citrus Sinensis</em>) in the Alcoleja Experimental Station (Eastern Spain) with clay-loam agricultural soils to assess the long-term effects of herbicides with inorganic fertilizers (H), intensive ploughing and i…
Responses of soil carbon and nitrogen transformations to stump removal
2012
We studied in central Finland whether stump harvesting after clear felling of coniferous forest poses further short-term changes in soil carbon and nitrogen dynamics when compared to the traditional site preparation method, mounding. Exposed mineral soil patches in Norway spruce (Picea abies) dominated clear-cut stands were sampled 1â5 years after the treatments. The extent of the exposed mineral soil surface was significantly larger at the stump removal sites when compared to the mounding sites. No differences were found in soil pH, organic matter content or total concentration of soil C between the treatments or treatment years. Total concentration of soil N was consistently higher and …
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…
Influence of inheritance and pedogenesis on heavy metal distribution in soils of Sicily, Italy
2000
Abstract The recognition of the potential health hazards associated with heavy metals has focused attention on the levels and behaviours of these elements both in natural and contaminated environments. Various soil types developed from different parent materials in Sicily, Italy, have been analysed in order to compare heavy metal distribution under different geopedological conditions. Total metal concentrations, metal partitioning and distribution profiles are discussed in relation to the inheritance factor and pedogenic processes. Parent material composition largely influences the contents of heavy metals in most of the analysed soils, mainly differentiating pedons for their metal concentr…
Selenium Partitioning and Stable Isotope Ratios in Urban Topsoils
2011
oxides. Th e δ82/76 Se values of total Se in the topsoils were close to the bulk Earth composition with an average δ82/76 Se value of −0.03 ± SD 0.38‰ suggesting that there was no or little Se isotope fractionation in soil. We attribute the small isotope fractionation to the low bioavailability of Se as a consequence of the presence of Fe oxides (adsorbing the dominating Se(IV) forms strongly), organic matter, and SO 4 2− (prevents biouptake of the Se(IV) forms) in the study soils. Small Se isotope fractionations of −0.59 to −0.35‰ in mainly forest soils and of 0.26 to 0.45‰ in mainly alluvial soils were presumably caused by soil/plant-recycling and Se contamination by river water, respecti…