The influence of mineral amendments on the changes in the organic nitrogen components of composts

Summary A series of straw composts, containing two levels of ammonium nitrate, were incubated with mineral amendments. Rate of decomposition was at a maximum over the first twenty days and was not influenced by the level of added nitrogne. The presence of bentonite and kaolinite reduced the loss of organic material slightly over the period of 150 days. In the low-N series, all the added inorganic nitrogen was immediately immobilized but in the high-N series inorganic N was slightly in excess of the microorganisms requirements. Little or no remineralization occurred. As a result of immobilization there was a rapid increase in amino acid and amino sugar nitrogen over the first 30 days and the values then remained fairly constant. The amino acid and amino sugar levels were slightly higher in the composts containing bentonite and kaolinite.In the early stages of the composting process, approximately half the organic nitrogen was soluble in phosphate buffer but the amount decreased with time of composting. Similarly, the amount of extracted nitrogen which could be hydrolysed by proteolytic enzymes, decreased with time. The composition of amino sugars liberated by acid hydrolysis suggested that chitin, probably of fungal origin, accounted for much of the amino sugar nitrogen and there is some evidence from oxidation studies for this. As composting proceeded, the amount of galactosamine increased and eventually muramic acid was identified indicating an increase in the bacterial flora.     

Sélaciens nouveaux du London Clay de l'Essex (Yprésien du bassin de Londres)

The Ypresian locality of Burnham-on-Crouch(Essex) has yielded numerous Selachian species, some of which are new: Hexanchus agassizi sp. nov., Scyliorhinus burnhamensis sp. nov., S. casieri sp. nov., S. pattersoni sp. nov., S. woodwardi sp. nov., Pararhincodon ypresiensis sp. nov., Triakis wardi sp. nov., Mustelus whitei sp. nov. The Hexanchid teeth classicaly refered to Notidanus serratissimusAg. include in fact two separate species belonging to different genera: Notorhynchus serratissimus (Ag.) and Hexanchus agassizi sp. nov. Lamna affinis (Casier) is arranged in the genus Isurolamna nov. in consideration of his dental peculiarities. The genus Burnhamia nov. is created for Rhinoptera daviesiWoodward that can be regarded as a Mobulid. Oxyrhina sheppeyensisCasier must be classified in the genus Anomotodon. The genus Triakis, Mustelus, Anomotodon and Pararhincodon are pointed out for the first time in the Ypresian.     

The relationship between EUF-K and soil-K fractions of different K selectivity

Summary The fraction of K released during EUF 30-35 min, 80°C, 400 V (EUF₃) and various other soil-K parameters were compared for 24 soils that range widely in clay mineral composition, clay content and percentage K saturation. When EUF₃ was compared with fractions of soil-K containing increasing amounts of non-exchangeable K (=selectively adsorbed K), the R² values decreased with increasing quantities of non-exchangeable K. This indicates that EUF₃ is a function of the exchangeable pool of K, although some initially non-exchangeable K is also involved.     

The effects of flooding for rice culture on soil chemical properties and subsequent maize growth

Summary The effects of flooding and lowland rice culture on soil chemical properties and subsequent maize growth were investigated in two contrasting rice soils of S.E. Australia. The effects of incorporating rice straw, either during or after flooding were also studied. The experiment was conducted in a glasshouse with the use of large intact soil cores.Previous flooding markedly reduced maize growth, leaf P concentration and P uptake, despite the application of a large quantity of P fertilizer after drainage. Soil analyses showed that previous flooding increased the Langmuir sorption terms for maximum P sorption and bonding energy. The availability of P was more closely related to the bonding energy between soil and P than to the capacity of the soils to sorb P. The increases, in the P sorption parameters, were associated with decreases in the crystallinity of the free iron oxides as determined by their oxalate solubility. It was concluded that depressed P supply to maize sown in previously flooded soils was due to stronger P sorption by the drained soils, rather than to P immobilization during flooding.Rice plants grown during flooding reduced the amount of N available to the subsequent maize crop, but did not significantly affect P availability. Rice straw added during flooding did not affect subsequent maize growth, but when added after flooding caused microbial immobilization of N.Salts, Fe or Mn from previous flooding did not affect maize growth.     

Prebiotic nucleotide oligomerization in a fluctuating environment: Effects of kaolinite and cyanamide

Summary The clay kaolinite was tested for its ability to promote nucleotide oligomerization in model prebiotic systems. Heterogeneous mixtures of clay, water and nucleotide were repeatedly evaporated to dryness at 60°C and redissolved in water in cyclic fashion in the presence or absence of cyanamide and/ or ammonium chloride. With or without cycling, kaolinite alone did not promote the oligomerization of nucleotides at detectable levels. Cycling of clay in combination with cyanamide, however, promoted high levels of condensation to a mixture of oligonucleotides and dinucleotide pyrophosphate without requiring ammonium chloride. Although cycling with clay favored synthesis of dinucleotide pyrophosphate, cycling without clay enhanced formation of oligonucleotides. These results support the hypothesis that the presence of clays in fluctuating environments would have influenced the course of prebiotic condensation reactions.     

Effect of external high pressures on the clay mineral sodium montmorillonite intercalated with methylated octadecylammonium bromide surfactants

Raman microprobe spectra of the clay mineral Wyoming SWy-2-sodium montmorillonite intercalated with the surfactants, methyltrioctadecylammonium bromide (TOMA) dimethyldiotadecylammonium bromide (DODMA) and octadecyl-trimethylammonium bromide (ODTMA), have been measured in the CH₂ stretching region at external pressures up to ∼40 kbar with the aid of a diamond-anvil cell. In the case of the intercalated clays containing TOMA and DODMA, the Raman data afford evidence for gauche to trans conformational changes in the orientation of the CH₂ chains in the surfactants with increasing pressure. These conformational changes are reversed completely upon the release of pressure.     

Analyse pollinique des dépôts lacustresdu Pléistocène inférieur de Banyoles (Bañolas,site de la Bòbila Ordis - Espagne): un élément nouveau dans la reconstitution de l'histoire paléoclimatique des régions méditerranéennes d'Europe occidentale

Clays from Bòbila Ordis near Banyoles have yielded a rich pollen flora. Three pollen zones are recognizable: the lower and the middle parts are dominated by components of a deciduous forest (with numerous exotic taxa); in the upper part, Pinus pollen and NAP (especially Compositae) are in a majority with an increase of mediterranean taxa towards the top. This floristic evolution may be connected with a climatic change characterized by a decrease in humidity which is itself linked to a world cooling. We suggest a possible relation with the pollen flora published by H. Elhai. The pollen diagram of Bòbila Ordis is the second so far established from Lower Pleistocene deposits in the Mediterranean countries of Western Europe; chronologically it follows the Bernasso (Languedoc) pollen diagram and confirms the latter results.     

Endothelium-lymphocyte interactions in vitro. II. Adherence of allergized lymphocytes.

Peripheral blood lymphocytes from skin graft-sensitized pigs will adhere in vitro to fresh donor-type large vessel endothelium, but do not spread out or migrate. Similar cells will however spread out on and migrate through monolayers of cultured donor-type aortic endothelium to a significantly greater extent than nonallergized lymphocytes. Cells sensitized in mixed lymphocyte culture at first exhibit a nonspecific increase in adherence and migration correlated with increased thymidine uptake, but after more prolonged incubation adherence becomes specific for stimulator-type endothelium. It is suggested that lymphocyte infiltration of an allograft in the presence of circulating sensitized cells involves a combination of nonspecific lymphocyte adhesion to endothelium, antigenic stimulation of “primed” cells to increased motility, endothelial penetration and lymphokine production, and soluble-factor-mediated stimulation of migration by nonsensitized cells.     

The role of seedbank and sown seeds in the restoration of an English flood-meadow

Abstract. In 1985 an opportunity arose to make use of an area (referred to as Somerford Mead) which had recently been used for intensive grass or cereal production but which originally had been a permanent hay-meadow. Situated on circum- neutral alluvial soils over limestone gravel, it is in close proximity to the River Thames and to species-rich flood meadows, including Oxey Mead (Fig. 1). This paper describes the early stages of an experiment to recreate a ‘typical’ flood-meadow community using seed harvested from Oxey Mead. Before sowing the seed, soil samples were taken and seedling emergence suggested that little of the original flood-meadow seed bank survived. Although Oxey Mead was known to contain at least 57 species, germination of samples of the sown seed in the glasshouse was confined to 12 species. All except Bromus commutatus and Trisetum flavescens and an additional nine Oxey Mead species were recorded in the field, together with 24 arable weed/ruderal species. Soil-nutrient contents (N, P and K) were high; so the restoration of this flood-meadow using only management techniques (hay cutting at the end of June and aftermath grazing) and the local seed bank would take a long time. The use of Alopecuros pratensis-Sanguisorba officinalis seed mixture was justified by the accelerated succession on Somerford Mead towards the parent community.     

Molecular Atomistic Simulations of Clay Swelling in Water Dispersions

An atomistic model has been constructed for a dimeric montmorillonite type clay aggregate. The solid was supposed to be dispersed in water. The surrounding aqueous phase was modified from pure water to either salt or polymer solution, and finally represented by a mixed solution containing electrolytes and polyols. A combined energy minimisation procedure followed by a 100 ps real time molecular dynamic simulation was performed on each amorphous cell modelling the solid dispersion. 3D periodic boundary conditions were established to ensure fluid spatial continuity and the calculations proceeded at room temperature. Sodium, potassium and calcium chlorides were tested as shale swelling inhibition additives. The lower hydration energy cation K⁺ was the most effective swelling inhibitor. The adsorption of poly(propylene glyco)s to the ideal smectite surface was also studied. Their tendency to remain adsorbed was associated with the irreversibility of the polymer adsorption process. The conformational changes obtained for organic molecules were responsible for the final orientation of the clay sheets. So it was possible to conclude from qualitative observations that intramolecular interactions may determine a clay dispersion–agglomeration transition by modifying the system entropy. Finally, it was also concluded that specific combinations of additives could enhance their individual capabilities by synergistic effects, determining the effectiveness for some water-based mud formulations. This revised version was published online in June 2006 with corrections to the Cover Date.