Labeled Oxygen: Increased Diffusion Rate through Soil Containing Growing Corn Roots

The diffusion of oxygen labeled with oxygen-18 through cores of wet soil increased significantly when roots of growing corn seedlings penetrated the cores. The increase was small or absent when roots grew through a layer of soft wax or a layer of water-saturated 0.5-mm glass beads, indicating that the diffusion increase was a joint effect of the roots and airfilled pores in the soil. A possible mechanism is suggested.     

Contact angle of soils as affected by depth, texture, and land management

Water repellency can be a significant factor in soil physical behaviour, but little is known about the depth dependence of the contact angle of field soils. We investigated contact angles and wetting properties as a function of depth for a wide range of agricultural and forest soils in Germany. The agricultural soils ranged from silty to sandy texture (six profiles), and the forest soils ranged from sandy to loamy texture (eight profiles). Contact angles (CA) were measured with the Wilhelmy plate method (WPM). In most of the soils, advancing WPM contact angles were considerably greater than 0° and they varied irregularly with depth. In general, sandy soils had larger WPM contact angles than silty soils. From the relation of the contact angle with texture and pH the quality of soil organic matter (SOM) was considered as more important for the wetting properties than the total amount of soil organic carbon (SOC). Finally, it was found that for soils with intermediate sand contents either under agricultural or forest use, the kind of land use seemed not to influence CA. Coarse‐textured sandy soils that were used only as forest sites were more hydrophobic than silty soils which were exclusively used as agricultural soils. We conclude that a coarse texture favours, in combination with other factors (mainly pH), hydrophobic SOM.     

Gaseous diffusion equations for porous materials

Commonly used equations of gaseous transport by diffusion are examined and the two parameters required for each equation are tabulated from the literature. The advantages and limitations of the commonly used linear —D/D_o = a(S?b) — and curvilinear — D/D_o = KS^m— equations are considered and a new diffusion equation is proposed to combine the advantages of the previous equations. This new equation, like the others, requires only two parameters. It takes the form D/D_o = [(S?u)/(1?u)]^v and may serve as a basis for studying and more accurately modeling gas transport in porous media.     

Tarago: A crisping potato released in South Eastern Australia

Tarago is a round, slightly netted, buff skinned potato cultivar with excellent crisping quality and mid-late maturity. It has high specific gravity, high yield and some resistance to late blight and powdery scab diseases.     

Leptospira icterohaemorrhagiae in New Zealand

Abstract

Extract

Sir:— In the recent letter from N. Inglis,(1) Inglis, N. 1984. Leptospira icterohaemorrhagia infection in deer. N.Z. vet. J., 32: 179–179. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar] an infection by Leptospira icterohaemorrhagiae in deer is postulated on the basis of serological evidence. Results of antibody testing with other serovars of Leptospira would be most informative and would reveal cross-reactions, which are known to occur freyuently. Further, the strain of L. icterohaemorrhagiae antigen and the type of test used would be of great interest to readers. Seroconversion to L. icterohaemorrhagiae serovar copenhageni, has been well documented since 1951.(2) Kirschner, L. and Gray, W.G. 1951. Leptospirosis in New Zealand. Infection with Spirochaela in animals and man. N.Z. med. J. L. No. 278, : 342–342.  [Google Scholar]     

Fiber types and size in equine skeletal muscle.

Frozen sections of equine musculus semitendinosus were examined for myosin adenosine triphosphatase (ATPase) and reduced nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), using standard histochemical procedures, and the proportions of the various fiber types and average fiber sectional size were determined. With ATPase staining, approximately 70% of the fibers were classified as alpha fibers (ATPase positive), and 30%, as beta fibers (ATPase negative). In addition, 2 populations of alpha fibers could be readily distinguished on the basis of the intensity of the ATPase reaction, and these were designated alpha positive and alpha intermediate. The relationship of this difference in ATPase reaction to contraction speed of the fibers is not known. With NADH-TR staining, fibers were classified as either red fibers (positive) having aerobic metabolism or white fibers (negative) having primarily anaerobic metabolism. All beta fibers were red by NADH-TR; thus, they conformed to the criteria for beta R fibers. All alpha positive fibers were white by NADH-TR, as were most of the alpha intermediate fibers, and would be classified alpha W. Some of the alpha intermediate fibers gave an intermediate reaction with NADH-TR and could be classified as alpha R fibers which have not transformed to alpha W fibers. The alpha positive fibers were 7 to 10 mum larger in diameter than either beta or alpha intermediate fibers.     

Surgical cleft soft palate repair in a foal

An Anglo-Arab foal with bilateral postprandial nasal discharge was diagnosed as having a full-length defect of the soft palate. Surgical repair was attempted using a combination of two surgical approaches. Initially a mandibular symphysiotomy approach was used. The posterior portion of the defect did not heal adequately, so a ventral laryngotomy, bisecting the body of the thyroid cartilage and extending to a pharyngotomy approach, was performed 5 months later. The foal has since matured fully despite a slight unilateral nasal discharge. This case report demonstrates that these two surgical approaches used simultaneously provide surgical access that is superior to either approach used individually.     

Elemental Composition of Twelve Plant Species Grown with Irradiated Municipal Sludge

The objective of this research was to determine the availability to plants of elements in sewage sludge irradiated with high-energy electrons for disinfection. Irradiated raw sludge (irradiated with an electron dose of 400 krad) and non-irradiated raw sludge were obtained from the Deer Island Wastewater Treatment Plant of Boston, Massachusetts. The sludges were used to grow 12 plant species under controlled-environmental conditions. The species were: bush bean (Phaseolus vulgaris L.), sweet corn (Zea mays L.), dill (Anethum graveolens L.), lettuce (Lactuca sativa L.), mustard (Brassica juncea Coss.), parsley (Petroselinum crispum Nym.), pumpkin (Cucurbita pepo L.), radish (Raphanus sativus L.), spinach (Spinacia oleracea L.), Swiss chard (Beta vulgaris cicla L.), tomato (Lycopersicon esculentum Mill.), wheat (Triticum aestivum L. em. Thell.). Plants were also grown with inorganic fertilizer added at recommended rates or with tap water. At the end of the experiment (44 days after planting), dry weight and elemental composition of the plants and soil (fine sandy loam, Typic Ustifluvent) were determined. There was no measurable difference in nutrient composition of soil treated with irradiated and non-irradiated raw sludge. In general, plants treated with irradiated raw sludge grew as well as plants treated with non-irradiated raw sludge. Most plants treated with sludge grew as well as plants treated with inorganic fertilizer. Elemental composition of plants treated with irradiated sludge was similar to that of plants treated with non-irradiated sludge. Sludge-treated dill, parsley, spinach, and Swiss chard had high concentrations of one or more of the following heavy elements: Zn, Cu, Ni, Cr. The results showed that plants grown with sludge irradiated with high-energy electrons were similar to plants grown with non-irradiated sludge.