Soon, Y. K., Arshad, M. A., Rice, W. A. and Mills, P. 2000. Recovery of chemical and physical properties of boreal plain soils impacted by pipeline burial. Can. J. Soil Sci. 80: [489][490][491][492][493][494][495][496][497]. Pipeline construction on the Canadian boreal plain occurs on woodland and/or agricultural fields, but soil recovery from its impact is not well documented. Therefore, we quantified changes over 3 yr (1992 to 1994) in the chemical properties of two Grey soils and the physical properties of a Grey soil that were subjected to pipeline burial and cropped to barley. The pipeline right-of-way (RoW) was divided into three zones: a road (or work) area used for vehicular traffic, a trench area for burying pipeline, and a pile (or spoil) area where soil was stockpiled during excavation. Pipeline construction resulted in mixing of subsoil material with topsoil, and the chemical properties most affected were those that varied most with depth. The pH, electrical conductivity, soluble sulphate, and exchangeable Ca and Na were increased in the surface 20 cm of soil, particularly the road and trench areas. The affected properties moderated 2 or 3 yr after pipeline construction as soluble components were dissolved or dispersed and translocated back to lower soil depths. The RoW zones had increased soil strength and compaction, and reduced water retention and infiltration rates. However, the deterioration in soil physical condition was similar across the RoW zones, indicating that it was due mainly to land clearing, a requirement to convert woodland to agricultural land. Improvement in bulk density, and water infiltration and retention in 1993 and 1994 indicated that the RoW was undergoing rehabilitation with time as a result of natural processes and annual cropping. Les oléoducs et gazoducs installés dans la plaine boréale canadienne traversent les forêts aussi bien que les terres agricoles, mais on ne dispose que de peu de données concrètes sur leurs effets. Nous avons quantifié pendant 3 ans (1992 à 1997) les modifications affectant les propriétés chimiques d'un Luvisol gris et d'un Solod gris foncé et les propriétés physiques du Solod, perturbés par la mise en place d'un oléoduc, puis semés en orge. L'emprise de l'oléoduc était divisée en trois zones : une bande de circulation pour les matériels de terrassement et de pose, l'emplacement de la tranchée d'enterrage du pipeline et la bande où avait été empilée la terre d'excavation. La pose de l'oléoduc provoquait le mélange du sous-sol avec la terre de surface et les propriétés chimiques les plus touchées étaient celles qui varient le plus en fonction de la profondeur. Le pH, la conductivité électrique et les teneurs en sulfates solubles et en Ca et Na échange-ables étaient plus élevées dans les 20 cm supérieurs du sol en particulier dans la bande de passage des machines et dans celle de la tranchée. Ces modifications s'atténuaient au bout de deux ou trois ans, les composants solubles étant dissous ou dispersés et retournés aux couches profondes du sol. Le...

Pipeline construction on the Grey soils of the Canadian boreal plains, which have a thin Ah horizon, could have considerable impact on their properties and productivity. This study was conducted because the effects of pipeline installation on crop yield and biological properties of these soils have not been well-documented. Soil was sampled from a Grey Luvisol and a Dark Grey Solod prior to pipeline construction in 1991, and in each of the following 3 yr. The right-of-way (RoW) was divided into three zones: a road (or work) area used for vehicular traffic; a trench where the pipeline was buried; and a pile (or spoil) area where soil was stockpiled during construction. The RoW was cropped to barley (Hordeum vulgare L.) in 1992 through 1994. Barley yield was low in 1992 (830–1120 kg ha−1), and near average (2050–3290 kg ha−1) in 1993 and 1994. Except for low shoot P concentration (1.1–1.3 mg g−1) in 1992, macronutrient concentrations (N, P and K) in barley tissues were within normal ranges. Soil organic carbon was reduced by 12–28% in all RoW areas in 1993 and 1994. Soil total N was reduced by 29–49% in all RoWs in 1992 and increased slightly from those levels in 1993 and 1994. Pipeline construction affected soil microbial biomass carbon (MBC) in the three RoW areas differently, and the effect was not consistent from year to year. However, the average level of MBC was not adversely impacted. In 1994, soil phosphatase activity in the RoW zones tended to be lower as compared to pre-pipeline installation, particularly in the pile area of the Dark Grey Solod. It is concluded that although some soil biological properties were degraded by pipeline construction, and barley yield was reduced in 1992, crop production in the following 2 yr was not significantly affected. Key words: Barley, carbon, microbial biomass, nitrogen, phosphatase, pipeline

Climate change studies have indicated the potential for increased drought in the southern Canadian prairies, and with this the potential exists for a northward shift in agricultural production areas. In order to assess the potential for agriculture, the arable soils of northwestern Canada (approximately north and West of 55"N latitude and 1 10°W longitude) and Alaska were sumrnarized. The study area was divided into several sub-regions or major land resource areas (MLRA) within which the soils with potential for agricultural use were identified through existing soil surveys. These surveys indicate an area of greater than 57 M hectares (Ha) of potentially arable land, which could be used for either annual cropping or grazing on perennial forages, according to the Canada Land Inventory class 1-5 criteria. The climatic limitations for each MLRA were assessed separately through the use of Climate Classification Software. These limitations were then applied to the 57 M Ha of potentially arable land identified earlier, with the result that the area was rated as overall class 5 climate, limited primarily by heat, and the size of the area was reduced to 39.2 M Ha. The impact of a 2 X COz changed climate on this area was then assessed by the use of climatic data generated with the Canadian Climate Centre, Global Circulation Model. These data show a much improved climatic capability for agriculture, being substantially warmer and somewhat drier. The overall climate class increased to a rating of 3, and 55.3 M Ha of arable land were shown to be potentially available in the study area.

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