The Hertz Corporation

About: The Hertz Corporation is a based out in . It is known for research contribution in the topics: Population & Soil water. The organization has 9562 authors who have published 11044 publications receiving 447929 citations. The organization is also known as: Hertz Rental Car & Hertz Rent-a-Car.

Enhancing the carbon sink in European agricultural soils: including trace gas fluxes in estimates of carbon mitigation potential

Abstract: The possibility that the carbon sink in agricultural soils can be enhanced has taken on great political significance since the Kyoto Protocol was finalised in December 1997. The Kyoto Protocol allows carbon emissions to be offset by demonstrable removal of carbon from the atmosphere. Thus, forestry activities (Article 3.3) and changes in the use of agricultural soils (Article 3.4) that are shown to reduce atmospheric CO2levels may be included in the Kyoto emission reduction targets. The European Union is committed to a reduction in CO2 emissions to 92% of baseline (1990) levels during the first commitment period (2008–2012). We have shown recently that there are a number of agricultural land-management changes that show some potential to increase the carbon sink in agricultural soils and others that allow alternative forms of carbon mitigation (i.e. through fossil fuel substitution), but the options differ greatly in their potential for carbon mitigation. The changes examined were, (a) switching all animal manure use to arable land, (b) applying all sewage sludge to arable land, (c) incorporating all surplus cereal straw, (d) conversion to no-till agriculture, (e) use of surplus arable land to de-intensify 1/3 of current intensive crop production (through use of 1/3 grass/arable rotations), (f) use of surplus arable land to allow natural woodland regeneration, and (g) use of surplus arable land for bioenergy crop production. In this paper, we attempt for the first time to assess other (non-CO2) effects of these land-management changes on (a) the emission of the other important agricultural greenhouse gases, methane and nitrous oxide, and (b) other aspects of the ecology of the agroecosystems. We find that the relative importance of trace gas fluxes varies enormously among the scenarios. In some such as the sewage sludge, woodland regeneration and bioenergy production scenarios, the inclusion of trace gases makes only a small (<10%) difference to the CO2-C mitigation potential. In other cases, for example the no-till, animal manure and agricultural de-intensification scenarios, trace gases have a large impact, sometimes halving or more than doubling the CO2-C mitigation potential. The scenarios showing the greatest increase when including trace gases are those in which manure management changes significantly. In the one scenario (no-till) where the carbon mitigation potential was reduced greatly, a small increase in methane oxidation was outweighed by a sharp increase in N2O emissions. When these land-management options are combined to examine the whole agricultural land area of Europe, most of the changes in mitigation potential are small, but depending upon assumptions for the animal manure scenario, the total mitigation potential either increases by about 20% or decreases by about 10%, shifting the mitigation potential of the scenario from just above the EU's 8% Kyoto emission reduction target (98.9 Tg C y−1) to just below it. Our results suggest that (a) trace gas fluxes may change the mitigation potential of a land management option significantly and should always be considered alongside CO2-C mitigation potentials and (b) agricultural management options show considerable potential for carbon mitigation even after accounting for trace gas fluxes.

The effects of biocidal treatments on metabolism in soil—III. The relationship between soil biovolume, measured by optical microscopy, and the flush of decomposition caused by fumigation

Abstract: The hypothesis that the flush of decomposition following fumigation is a measure of the amount of biomass in a soil was tested by comparing the biomass thus found, and as calculated from direct microscopic measurement of the soil biovolume. Eight soils developed under contrasting systems of management and climate were used, six from England and two from Nigeria. The biovolume was measured by a modification of the Jones and Mollison procedure, in which agar films prepared from known amounts of soil were stained with phenolic aniline blue. Fluorescent stains were less satisfactory in that they did not stain as wide a range of organisms as phenolic aniline blue. Spherical organisms were divided into 13 size classes, with diameters ranging from 0·3 to 19 μm, and the numbers in each size class counted. Hyphae were divided into seven diameter classes, with dia. ranging from 1 to 11 μm, and the lengths in each class measured. For seven of the soils there was close agreement between the two different methods of measuring biomass C. With an acid woodland soil (pH 3·9). the biomass C, as calculated by direct microscopy, was seven times that calculated from the size of the flush; it is suggested that this discrepancy arose because stainable cell walls from dead organisms persist for much longer in the strongly acid soil than in the other, more nearly neutral, soils. Both methods were used to follow the effects of fumigation on the soil biomass. A near-neutral soil was fumigated with CHCl3, the fumigant removed and the soil incubated for 53 days at 25° C. The decrease in biomass caused by fumigation was less as measured by direct microscopy than as measured from the size of the flush, suggesting that stainable cell walls of killed organisms can persist for a considerable time after fumigation. Data on the relationship between the size of soil organisms and their contribution to soil biovolume are presented graphically. The biovolume in hyphae and in ‘spherical’ organisms was roughly equal in all soils. There was a linear relationship between the cumulative biovolume and the logarithm of organism volume lor ‘spherical’ organisms over the volume range 0·05 μm3 to 100 μm3. If, for a given soil, the volume range is divided into equal volume classes on a logarithmic basis, each class contains the same biovolume. Thus, comparing equal logarithmic volume classes, a class of rare large organisms contains as much biovolume as a class of numerous small organisms.

Data integration by object management

Abstract: An object based data processing system including an extensible set of object types and a corresponding set of "object managers" wherein each object manager is a program for operating with the data stored in a corresponding type of object. The object managers in general support at least a standard set of operations. Any program can effect performance of these standard operations on objects of any type by making an "invocation" request. In response to an invocation request, object management services (which are available to all object managers) identifies and invokes an object manager that is suitable for performing the requested operation on the specified type of data. A mechanism is provided for linking data from one object into another object. A object catalog includes both information about objects and about links between objects. Data interchange services are provided for communicating data between objects of different types, using a set of standard data interchange formats. A matchmaker facility permits two processes that are to cooperate in a data interchange operation identify each other and to identify data formats they have in common. A facility is provided for managing shared data "resources", Customized versions of resources can be created and co-exist with standard resources. A resource retrieval function determines whether a customized or a standard resource is to be returned in response to each request for a resource.

Denitrification in soil. I. Methods of investigation

Abstract: 1. Methods of investigating denitrification in soil are critically discussed with special reference to methods based on total-N analysis.2. A modified Kjeldahl method of determining nitrogen which includes nitrate and nitrite and is applicable to waterlogged soil is described and the use of this method in studies on denitrification in soil is illustrated and discussed.3. It is shown that rapid denitrification of nitrate in soil can be induced by incubating the soil under waterlogged conditions with organic materials such as glucose and that denitrification can be followed by total-N analyses if the organic material used to induce denitrification is not added in such excess that it also promotes significant fixation of atmospheric nitrogen.4. The percentage of added nitrate-N lost by denitrification on incubation of waterlogged soils with different amounts of nitrate and sufficient glucose for denitrification was found to be the same whatever the level of application of nitrate.5. Denitrification of nitrate in waterlogged soil containing glucose was found to be accompanied by a rapid but temporary accumulation of large quantities of nitrite and by the formation of smaller amounts of ammonia. Hydroxylamine could not be detected during denitrification, but it was found that this compound was rapidly decomposed in the soils examined by a process which appeared to be purely chemical.6. It is shown that denitrification of nitrate in soil is a microbiological process and that the viability of the micro-organisms responsible for denitrification is not affected by air-drying and storage of the soil.

Long-term effects of nitrogen fertilization on methane oxidation in soil of the broadbalk wheat experiment

Abstract: Methane uptake by a temperate arable soil was investigated in incubation experiments with intact soil cores. The measurements were carried out with a soil moisture content of 16–17% (w/w) and at 25°C. The decrease of the CH 4 concentrations in an amended atmosphere (10 μl CH 4 1 −1 ) was measured during a 212 h period. There was no decrease of CH 4 if the soil was autoclaved showing that the disappearance of methane was entirely mediated by microbial activity. The long-term application (140 yr) of mineral nitrogen fertilizer caused significant differences in the ability of the soil to oxidize CH 4 : the larger the amount of fertilizer applied the lower the rate of CH 4 oxidation. No significant short-term effect of mineral-N fertilization could be observed whether applied as (NH 4 ) 2 SO 4 or KNO 3 . An organic manure treatment, which has received nearly 240 kg N ha −1 each year as farmyard manure, showed almost the same ability to oxidize CH 4 as an unfertilized plot and had a significantly higher CH 4 oxidation rate after an application of 144kg N ha −1 as nitrate fertilizer. For the mineral-N treatments the inhibition of the CH 4 oxidation increased with increasing N turnover rate but was independent of the mineral nitrogen content of the soil at the time of measurement. Therefore, the continued application of mineral-N fertilizer for an extended period (at least 7 yr) caused a depletion of the bacterial methane sink in soil and may have contributed to the continuous increase in atmospheric CH 4 over the past decades.