The disposal of hazardous and radioactive waste in arid regions requires a thorough understanding of the occurrence of soil‐water flux and recharge. Soil‐water chemistry and isotopic data are presented from three deep vadose zone boreholes (>230 m) at the Nevada Test Site, located in the Great Basin geographic province of the southwestern United States, to quantify soil‐water flux and its relation to climate. The low water contents found in the soils significantly reduce the mixing of tracers in the subsurface and provide a unique opportunity to examine the role of climate variation on recharge in arid climates. Tracing techniques and core data are examined in this work to reconstruct the paleohydrologic conditions existing in the vadose zone well beyond the timescales typically investigated. Stable chloride and chlorine 36 profiles indicate that the soil waters deep in the vadose zone range in age from approximately 20,000 to 120,000 years. Secondary chloride bulges that are present in two of the three profiles support the concept of recharge occurring at or near the last two glacial maxima, when the climate of the area was considerably wetter and cooler. The stable isotopic composition of the soil water in the profiles is significantly more depleted in heavy isotopes than is modern precipitation, suggesting that recharge under the current climate is not occurring at this arid site. Past and present recharge appears to have been strongly controlled by surface topography, with increased incidence of recharge where runoff from the surrounding mountains may have been concentrated. The data obtained from this detailed drilling and sampling program shed new light on the behavior of water in thick vadose zones and, in particular, show the sensitivity of arid regions to the extreme variations in climate experienced by the region over the last two glacial maxima.

The link between livestock production, manure management, and human health has received much public attention in recent years. Composting is often promoted as a means of sanitizing manure to ensure that pathogenic bacteria are not spread to a wider environment during land application. In a two-year study (1998 and 1999) in southern Alberta, we examined the fate of coliform bacteria during windrow composting of cattle (Bos taurus) manure from feedlot pens bedded with cereal straw or wood chips. Numbers of total coliforms (TC) and Escherichia coli declined as the composting period progressed. In 1998, TC levels (mean of both bedding types) were log10 7.86 cells g(-1) dry wt. for raw manure on Day 0, log10 3.38 cells g(-1) by Day 7, and log10 1.69 cells g(-1) by Day 14. More than 99.9% of TC and E. coli was eliminated in the first 7 d when average windrow temperatures ranged from 33.5 to 41.5 degrees C. The type of bedding did not influence the numbers of TC or E. coli. Dessication probably played a minor role in coliform elimination, since water loss was low (< 0.07 kg kg(-1)) in the first 7 d of composting. However, total aerobic heterotroph populations remained high (> 7.0 log10 CFU g(-1) dry wt., where CFU is colony forming units) throughout the composting period, possibly causing an antagonistic effect. Land application of compost, with its nondetectable levels of E. coli compared with raw manure, should minimize environmental risk in areas of intensive livestock production.

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. 2004. Barley dry matter yield, crop uptake, and soil nutrients under fresh and composted manure containing straw or wood-chip bedding. Can. J. Plant. Sci. 84: 987-999. Limited information exists on the effect of fresh versus composted beef cattle manure containing straw or wood chips on barley (Hordeum vulgare) yield, nutrient uptake, and soil nutrient status in the Great Plains region of North America. Barley was grown on an irrigated clay loam soil in southern Alberta from 1999 to 2001. The treatments were three rates (13, 39, 77 Mg dry material per hectare) of fresh manure (FM) or composted manure (CM) containing either straw (ST) or wood-chip (WD) bedding, one inorganic (IN) fertilizer treatment (100 kg N ha -1 , 17 kg P ha -1 ), and a control treatment; applied in the fall of 1998, 1999, and 2000. Dry matter yield was not significantly (P > 0.05) influenced by manure type or bedding material. Crop protein was 7% higher under FM (12.7 g kg -1 ) than CM (11.9 g kg -1 ) in 2001, and crop N uptake was 11 to 13% higher for CM-ST (171.3 kg ha -1 ) and FM-WD (174.9 kg ha -1 ) than CM-WD (154.7 kg ha -1 ) over the 3 yr. Soil available N was 20 to 261% higher for FM than CM at the 39 and 77 Mg ha -1 rates, and it was 62 to 199% higher for FM than CM in 2000 and 2001. Soil available N was 48 to 57% higher for ST than WD at the two higher application rates, and it was 26 to 65% higher for ST than WD in all 3 yr. Overall, manure type and bedding influenced certain crop and soil parameters, and higher available soil N under FM and ST indicated a potential for greater mineralization under these treatments. On manque de données sur l'incidence du fumier de bovins frais ou composté renfermant de la paille ou des copeaux de bois sur le rendement de l'orge (Hordeum vulgare), l'absorption des nutriments par la plante et le bilan d'éléments nutritifs dans le sol pour la région nord-américaine des grandes plaines. De 1999 à 2001, les auteurs ont cultivé de l'orge sur un loam argileux irrigué dans le sud de l'Alberta. À l'automne de 1998, 1999 et 2000, ils ont appliqué à la culture trois quantités (13, 39 ou 77 Mg de matière sèche par hectare) de fumier frais (FF) ou composté (FC) à base de paille (P) ou de copeaux de bois (CB), un engrais minéral (100 kg de N et 17 kg de P par hectare) ou un traitement témoin. Le type de fumier ou la nature de la litière n'agit pas de manière significative (P > 0,05) sur le rendement en matière sèche. En 2001, l'orge obtenue avec le FF avait 7 % de protéines (12,7 g par kg) de plus que l'orge cultivée avec du FC (11,9 g par kg); les combinaisons FC-P et FF-CB ont aussi permis à la plante d'absorber 11 à 13 % plus de N que la combinaison FC-CB au cours des trois années de l'expérience (171,3 et 174,9 kg par hectare c. 154,7 kg par hectare, respectivement). L'usage de FF a accru la quantité de N disponible dans le sol de 20 à 261 % par rapport au FC, aux taux de 39 et de 77 Mg par hectare, et de 62 à 199 %, en 2000 et en 2001. Comparativement aux copeaux de bois, la paille augmente la concentra...

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