No abstract

One of the many gaps that needs to be solved by precision agriculture technologies is the availability of an economic, automated, on-the-go mapping system that can be used to obtain intensive and accurate 'real-time' data on the levels of nitrate nitrogen (NO 3 -N) in the soil. A soil nitrate mapping system (SNMS) has been developed to provide a way to collect such data. This study was done to provide extensive field-scale validation testing of the system's nitrate extraction and measurement sub-unit (NEMS) in two crop (wheat and carrot) production systems. Field conditions included conventional tillage (CT) versus no tillage (NT), inorganic versus organic fertilizer application, four soil groups and three points in time throughout the season. Detailed data analysis showed that: (i) the level of agreement, as measured by root mean squared error (RMSE), mean absolute error (MAE) and coefficient of efficiency (CE), between NEMS soil NO 3 -N and standard laboratory soil NO 3 -N measurements was excellent; (ii) at the field-scale, there was little practical difference when using either integer or real number data processing; (iii) regression equations can be used to enable field measurements of soil NO 3 -N using the NEMS to be obtained with laboratory accuracy; (iv) future designs of the SNMS's control system can continue to use cheaper integer chip technology for processing the nitrate ionselective electrode (NO 3 --ISE) readings; and (v) future designs of the SNMS would not

Electron microprobe examination of glass-encased magnetites present within surficial volcanic ash deposits located in Banff and Jasper National Parks revealed five distinct magnetite populations. Three of the magnetite populations represented the Mazama, St. Helens Y, and Bridge River volcanic units previously identificd in this area of the Canadian Kocky Mountains. The reinaining two magnetite groups are characterized by glass-encased magnetites which have titanium oxide concentrations of 11.59 and lQ.33%, values considerably higher than thosc characteristic of either Mazama, St. Helens Y, or Bridge River volcanic units. The high-titanium magnetites are of unknown provenance, and although the section provided no means for dating these volcanic groups, their distribution within the section suggests that they are older than Bridge River, and one group may predate Mazama.I.'examen B la microsonde electronique des grains de magnitite enrobks de ven-e qu'on retrouve dans les depbts de cendres volcaniques superficiels dans les parcs nationaux de Banff et de Jasper a revkle cinq populations distinctes de magnetite. Trois dcs populations de magnetite representent les unites volcaniques de Mazama, de St. Helens Y et de Bridge Kiver dkj2 reconnues dans cette partie des montagnes Kocheuses canadiennes. Les deux autres groupes de magnetite sont caracterises par des magnetites enrobees de verre qui ont des concentrations en oxyde de titane de 11.59 et de 10.33%, valeurs qui sont considerablement plus ilevees que celles des unites de Mazama, de St. Helens Yet de Bridge River. On ne connait pas la provenance de ces magnetites riches en titane et bien que la coupe ne permette pas de dater ces groupes volcaniques, leur distribution ii I'interieur de la coupe suggere yu'ils sont plus anciens que I'unite de Bridge ----

Controlling soil erosion and the transport and deposition of suspended sediment to receiving waters, especially in relation to the modifying influences of, and interplay between, climate and land-use alterations, is essential for effective watershed management. The Atlantic Canada-New England region is expected to experience elevated rainfall erosivity due to climate change over the next century. Using the projected higher precipitation amounts of 5% and 10% for future scenarios of 5 and 25 years for the region, and a spatially-explicit, integrated (GIS, RUSLE) model for a rural watershed in Nova Scotia, predicted increases in total erosion rates of 4.9 and 9.9%, respectively. Modelled scenarios altering buffer strips based on either consistent or slope-variable widths between 30 m (the legal requirement) to 90 m were found to correspond to reductions in predicted total watershed erosion rates from 11% to 32%. Assuming and extending the 1:1 concordance between projected precipitation and estimated soil erosion for this particular watershed into the more distant future of 26 to 55 years, suggests that the 25% increase in soil erosion predicted over this period would have to be offset by expanding the protective buffer strips to a consistent width of 70 m. Adoption of such a protective management scheme would subsume 19% of the terrestrial area of the study watershed and thus consequent reductions in land available for agricultural production and timber harvest.

The effects of NaOAc removal of carbonates, HzOz removal of organic materials, and sodium citrate-bicarbonate-dithionite (SCBD) removal of iron oxides upon the X-ray powder diffraction (XRD) characteristics of clay minerals present within weathered volcanic ash deposits were examined. All pretreatments of samples derived from the Ae and Bhf horizons containing volcanic ash resulted in dramatic increases in XRD peak intensities, while the treatment of IIC-horizon samples resulted in subdued XRD peak intensities. Also, the chemical treatments produced an apparent increase in the amount of expandable clay minerals within the Ae horizon, due probably to the hydrolysis and removal of interlayer A1 z+ when H~O~ and SCBD were used. Hence, poorly ordered and pedogenicaUy modified vermiculite or vermiculite/ montmorillonite interstratifications became "weathered" by H + attack and AP § removal in a manner similar to the natural processes which take place in the acid and eluvial A horizon. In addition, possible XRD peak modification due to the dilution of crystalline clay concentrations 'by amorphous clay-size material appeared to be subordinate to the laboratory-induced chemical alteration of the weathered clay minerals.