Hydrological structure and erosion damage caused by concentrated flow in cultivated catchments     

Bruno Ludwig  Jean Boiffin  Joël Chaduf  Anne-Vronique Auzet 《CATENA》1995,25(1-4)

This study analyses the between-catchment variability of rill volumes produced by concentrated flow erosion during winter in the northern part of the Paris Basin. The working hypotheses were that (i) runoff concentrates along channels determined by topography or by agricultural practices; (ii) rill length is a major component of rill volume variability on a catchment scale; (iii) rill cross-sectional areas are controlled by the size of upslope runoff-contributing areas connected to the corresponding channels. Two samples, one of 20 zero order catchments and the other of 15 catchments, were surveyed. For each catchment, the runoff collector network was modelled from topographical and agricultural information, and split into homogeneous segments. Each segment was characterized by its slope gradient (SL), the soil susceptibility to rill erosion (SSE) and the size of the upslope runoff-contributing areas (RCA) connected to it. These areas were identified by the structural state of their soil surface. The frequency of rill occurrence was highly correlated with RCA and SL. The rill cross-sectional areas of eroded channels were correlated with RCA, SL and SSE. Catchment erosion rates were estimated by adding together the predicted rill volumes for each segment within the catchment. These estimations were closely correlated with observed rill erosion rates. The relative spatial position of runoff collectors must be taken into account when examining the damage caused by concentrated flow erosion.  相似文献   

Emissions of N₂O from soils during cycles of freezing and thawing and the effects of soil water, texture and duration of freezing     

R. Teepe  A. Vor  F. Beese  & B. Ludwig 《European Journal of Soil Science》2004,55(2):357-365

Freezing and thawing influence many physical, chemical and biological processes in soils, including the production of trace gases. We studied the effects of freezing and thawing on three soils, one sandy, one silty and one loamy, on the emissions of N₂O and CO₂. We also studied the effect of varying the water content, expressed as the percentage of the water‐filled pore space (WFPS). Emissions of N₂O during thawing decreased in the order 64% > 55% > 42% WFPS, which suggests that the retardation of the denitrification was more pronounced than the acceleration of the nitrification with increasing oxygen concentration in the soil. However, emissions of N₂O at 76% WFPS were less than at 55% WFPS, which might be caused by an increased ratio of N₂/N₂O in the very moist conditions. The emission of CO₂ was related to the soil water, with the smallest emissions at 76% WFPS and largest at 42% WFPS. The emissions of CO₂ during thawing exceeded the initial CO₂ emissions before the soils were frozen, which suggests that the supply of nutrients was increased by freezing. Differences in soil texture had no marked effect on the N₂O emissions during thawing. The duration of freezing, however, did affect the emissions from all three soils. Freezing the soil for less than 1 day had negligible effects, but freezing for longer caused concomitant increases in emissions. Evidently the duration of freezing and soil water content have important effects on the emission of N₂O, whereas the effects of texture in the range we studied were small.  相似文献   

The nature and origins of diester phosphates in soils: a 31P-NMR study   总被引：2，自引：0，他引：2  

Makarov  M.  Haumaier  L.  Zech  W. 《Biology and Fertility of Soils》2002,35(2):136-146

Soils of two climosequences in Russia were investigated by ³¹P-NMR spectroscopy. They comprised Dystric Podzoluvisols, Haplic Greyzems, Calcic Chernozems, and Gypsic Kastanozems, which are located along temperature and precipitation gradients of the Russian Plain. Another sequence of soils included forest Humic Cambisols and Umbric Leptosols of subalpine and alpine meadows, which are formed in different climatic conditions along a climosequence of the Mt. Malaya Khatipara (northern Caucasus). The results showed that accumulation of DNA was high in the cold, wet, and acid soils (Dystric Podzoluvisol, alpine Umbric Leptosol), while phospholipids and teichoic acids mainly accumulated in the more microbially active soils. We performed a laboratory incubation experiment to test the relationship between microbial biomass P and P species identified in soil extracts. The proportions of P compounds resonating at 0.5-3.0 ppm in the NaHCO₃ and H₂SO₄ extracts from the incubated Humic Cambisol increased. The amounts of phosphate diesters resonating at 0 ppm in the same extracts and in the subsequent NaOH extracts decreased after incubation. Based on the results of ³¹P-NMR spectroscopy of native soils and of the laboratory incubation experiment we concluded that signals at 0 ppm in spectra of soil alkaline extracts belong to DNA P which is mainly stabilised in soil organic matter outside microbial cells (at least in soils with relatively low microbial activity). Phospholipids-teichoic acids P extracted with 0.5 M NaHCO₃ seems to be derived from soil microbial biomass, and its proportion can reflect the microbial activity in the soil.  相似文献   

Modelling of sorption experiments and seepage data of an Amazonian Ultisol subsoil under cropping fallow     

Bernard Ludwig  Dirk Hlscher  Partap Khanna  Jürgen Prenzel  Horst Flster 《植物养料与土壤学杂志》1997,160(4):447-454

The results of physico-chemical investigations of an Ultisol subsoil under a 2-year old fallow in eastern Amazonia are presented. Subsoil chemistry was studied using 4 different approaches: i) concentrations of H, Na, K, Ca, Mg, Mn, Al, and Fe in seepage water were measured under field conditions, ii) the equilibrium soil chemistry was studied in sequential batch experiments where the soil was treated with different solutions, iii) results of batch experiments were simulated with a chemical equilibrium model, and iv) the seepage data were calculated using selectivity coefficients obtained by modelling the batch experiments. The model included multiple cation exchange, precipitation/dissolution of Al(OH)₃ and inorganic complexation. Cation selectivity coefficients were pK_x/Ca^sel: X = Na: 0.3, K: 0.8, Mg: ?0.1, and Al: 0.4. The amount of cations sorbed ranged from ?0.2 to 2.0 (K), ?0.7 to 2.3 (Mg), ?1.6 to 1.8 (Ca), ?4.8 to 3.6 (Al) and 0.0 to 8.5 (Na) mmol_c kg^?1. The model predictions were good with values lying within 0.3 pH units (for the pH range 3.7 to 7.2), and 3% of CEC for individual cations. The most important proton buffer reaction seemed to be the dissolution of gibbsite and a large release of Al into the soil solution. When selectivity coefficients obtained by the modelling procedure were used to predict the field data for cation concentrations in the seepage water, they decreased in the following order: Na > K > Ca > Mg > Al. These calculated values were similar to the measured order: Na > Ca > K ≈ Mg > Al. Thus the options for managing these soils should be carefully chosen to avoid soil acidification which may result from inappropriate use of fertilizer during the cropping period.  相似文献   

Effects of supplemental iron and copper on lipid oxidation in milk. 1. Comparison of metal complexes in emulsified and homogenized milk   总被引：1，自引：0，他引：1  

J Hegenauer  P Saltman  D Ludwig  L Ripley  P Bajo 《Journal of agricultural and food chemistry》1979,27(4):860-867

  相似文献   

Über Hangschuttbildung,Plateaulehme Und Junge Erosion Im “Hochwald”: Westlicher Hunsrück,Rheinisches Schiefergebirge     

Ludwig Zöller 《CATENA》1980,7(1):153-167

  相似文献   

Experiences with the Riems vaccine combination PI-3 and Riems IBR/IPV vaccines in cattle-raising stock     

O Deja  C Ludwig  H J Ludwig  H W?hler 《Archiv fuer experimentelle veterinaermedizin》1987,41(6):914-918

  相似文献   

Clinically Diseased Cats with Non-suppurative Meningoencephalomyelitis have Borna Disease Virus-specific Antibodies     

A.-L. Lundgren  H. Ludwig 《Acta veterinaria Scandinavica》1993,34(1):101

A spontaneous neurological disease in cats characterized by behavioural and motor disturbances was reported in Sweden by Kronevi et al (1974). Generally, the animals showed no gross pathological lesions. Detailed neuro-pathological investigation revealed mononuclear perivascular cuffing and gliosis throughout the brain and spinal cord consistent with a non-suppurative meningoencephalomyelitis. After this first report, the disease has become recognized in different parts of Sweden, preferably Uppland and the area around Lake Mälaren, and is referred to as “staggering disease” of cats. The clinical manifestation of the disease includes hindleg ataxia and paresis (Fig. 1), inability to retract the claws (Fig. 2), mental changes, anorexia, increased salivation, hypersensitivity to sound and light, hyperesthesia, impaired vision and seizures (Kronevi et al 1974, Ström et al 1992). Despite treatment with antimicrobial drugs and corticosteroids most cats deteriorate and die or have to be euthanised after 1-4 weeks of illness.  相似文献   

Diagnosis of HEV infection in the suckling pig     

H J Ludwig  C Ludwig  U Kücken 《Archiv fuer experimentelle veterinaermedizin》1987,41(6):900-903

  相似文献   

Fungal isolation and identification in 21 cases of guttural pouch mycosis in horses (1998-2002)     

Ludwig A  Gatineau S  Reynaud MC  Cadoré JL  Bourdoiseau G 《Veterinary journal (London, England : 1997)》2005,169(3):155-461

This aetiological study of guttural pouch mycosis (GPM) in the horse was based on the retrospective study of 21 horses brought into the National Veterinary School of Lyon (France) between 1998 and 2002. Biopsies were taken from the lesions caused by GPM during endoscopic examination. In 87% of the cases, direct examination gave positive results, whereas 43% of the cultures were found to be negative. The main fungi observed were Aspergillus fumigatus (in three cases), A. versicolor (in two cases, together with other fungi), and A. nidulans and A. niger (one case each). In six cases, the Aspergillus species could not be identified. In two cases, cleistothecia and/or Hulle cells were observed. In three cases, fungi other than Aspergillus were seen, mixed or not with Aspergillus. These results underline the importance of Aspergillus fumigatus in the development of GPM in horses.  相似文献