GRASSLAND FERTILIZER PRACTICE AND HYPOMAGNESAEMIA

The effects of N and K fertilizers on the yield and chemical composition of herbage and the serum Mg and Ca levels of grazing ruminants were investigated, using 64 lactaling ewes in a 4x4 Latin square arrangement of plots. During the 2-year experiment there was no evidence that application of N alone has a depressing effect on the Mg content of either herbage or blood serum. The sheep grazing plots treated with combined N and K fertilizer had significantly (P<0·01) lower serum Mg levels during the early spring grazing period of 1961. It is suggested that individual variability within a group of animals may considerably influence the results of investigations of this kind.     

Evaluation of Poultry Litter Amendment to Agricultural Soils: Leaching Losses and Partitioning of Trace Elements in Collard Greens

Water, Air, &; Soil Pollution - Leaching of trace metals and greenhouse plant growth (Collard greens; Brassica oleracea var. acephala) response studies were conducted in two types of soils with...     

Modelling soil physical behaviour with particular reference to soil science

Soil is a very complex material. It consists of three interacting phases, namely solid, liquid and gas phase, which participate in a number of different processes controlling physical soil behaviour. These include water, solute and heat flow, mechanical stress–strain displacement and failure under shear and tensile forces. Often physical soil behaviour is investigated by treating either process in isolation rather than accounting for their interdependency. This is probably related to the multiplicity and complexity of interactions that need to be combined to fully represent the physical response of soils to variable environmental conditions. This paper describes a computer model that can analyze hydraulic and mechanical processes interactively. However, the computer model by itself is not sufficient, as the accuracy of modelling depends on the sampling, testing and verification of the soils analyzed in the soil problem. Some applications of modelling soil physical behaviour in soil science are presented.     

Sedimentary profiles of pollution marker chemicals along a large tributary of Chesapeake Bay (mid-Atlantic USA)

Journal of Soils and Sediments - Molecular markers in environmental geochemistry include natural product or pollutant chemicals in sediments that are indicative of discharge sources or emission...     

HydroLOGIC: An irrigation management system for Australian cotton

The worldwide need to improve water use efficiency within irrigated agriculture has been recognised in response to environmental concerns and conflicts in resource use. Within the Australian cotton industry, the imperative to reduce water use and optimise irrigation management through the understanding of risk, using information generated by computerised decision aids was identified and subsequently developed into the HydroLOGIC irrigation management software. This paper summarises the attributes of the HydroLOGIC irrigation management software, with particular emphasis on functionality and its application to irrigation decisions within the Australian cotton industry. The software development process is documented to provide direction for future software application initiatives, with particular emphasis on a process of user feedback, evaluation and support requirements providing direction to software development. On-farm experiments throughout the development period allowed the validation of internal software logic, irrigator decision processes, and the OZCOT cotton growth model. The software demonstrated the ability to improve yield and water use efficiency by optimising strategic and tactical irrigation decisions in the Australian furrow irrigation cotton production system. In 7 of the 11 on-farm experiments conducted, the use of HydroLOGIC helped improve overall field water use efficiency by optimising the timing of irrigation events or by indicating further irrigations would not provide yield or maturity benefits. The paper also presents useful insights into the development of software targeted for irrigation utilising in-field measurements of soil water, crop growth and a crop growth simulation model.     

Gill pathology in Scottish farmed Atlantic salmon,Salmo salar L., associated with the microsporidian Desmozoon lepeophtherii Freeman et Sommerville, 2009

Gill disorders have emerged in recent years as a significant problem in the production of marine‐stage Atlantic salmon Salmo salar L. The multi‐aetiological condition ‘proliferative gill inflammation’ (PGI) has been reported to cause heavy losses in western Norway, yet reports of Scottish cases of the disease have remained anecdotal. In the present study, histopathological material from a marine production site in the Scottish Highlands experiencing mortalities due to a seasonal gill disease with proliferative‐type pathology was examined using light microscopy, special staining techniques and transmission electron microscopy (TEM). The microsporidian Desmozoon lepeophtherii Freeman et Sommerville, 2009 (syn. Paranucleospora theridion) was identified by staining using a Gram Twort method and TEM associated with distinctive proliferative and necrotic pathology confined to the interlamellar Malpighian cell areas of the primary filaments. Epitheliocystis was not a feature of the gill pathology observed. It is believed this is the first report of D. lepeophtherii being identified associated with pathology in a Scottish gill disease case, and supports anecdotal reports that a disease at least partly synonymous with PGI as described by Norwegian researchers is present in Scottish aquaculture.