ALBERT

Description: Efficient liquid manure application systems that minimize ammonia volatilization are required for use on perennial forage grasses. Ammonia volatilization was monitored using wind tunnels for 10 d after three pig slurry applications using four boom-mounted applicators: a broadcast splash-plate system, a trailing-shoe system and a drag-hose system with and without previous soil aeration. Average losses of 32, 20 and 15% of the total ammonia-N (TAN) applied to plots were observed for the splash-plate, the trailing-shoe and the drag-hose systems, respectively. The grass canopy intercepted, on average, 14% of pig slurry TAN using the splash-plate system compared with 4% for the trailing-shoe and 5% for the drag-hose systems. Reductions in canopy interception explained 58% of differences in volatilization rates among the application systems. On two of three application dates, NH3 volatilization was lower using the drag-hose than the trailing-shoe system. This was attributed to the sealing of the soil surface by the passage of the trailing-shoe, which decreased slurry infiltration rate. Ammonia volatilization was not reduced by soil aeration prior to slurry application using a drag-hose system likely because aeration did not increase slurry infiltration into the soil. Producers could be advised to reduce volatilization losses by using a simple drag-hose system to avoid application of slurry to leaf canopies. Key words: Ammonia volatilization, liquid hog manure, pig slurry, application method, ammonium

Description: The sustainability of organic dairying in Canada, with respect to nutrients, remains unexamined. To assess how management affects nutrient status, we documented whole farm nutrient (NPK) budgets over 2 yr (2003 to 2005) and soil (0 to 15 cm) P and K status on 15 long-term Ontario organic dairy farms. Farm size, livestock density and herd productivity averaged 110 ha, 1.00 livestock units ha-1 and 5656 kg milk cow-1 yr-1, respectively. Annual farm nutrient surpluses of 75 (N), 1 (P) and 11 (K) kg ha-1 yr-1 were lower than those reported for confinement-based dairy farms in the United States, pointing to possible environmental benefits from reduced off farm impacts on air and water quality. Weighted average soil test P levels were low (〈 10 mg kg-1) on approximately 50% of farms, while exchangeable K levels were moderate to high (76 to 160 mg kg-1) on all farms. Four farms adopting a "self-sufficient" approach, producing most feed on-farm, imported little P as feed (1.37 to 1.90 kg P ha-1 yr-1) and had negative average farm P balances (avg. -1.54 kg P ha-1 yr-1). An integrated nutrient management approach, along with a flexible feed import strategy, fosters the sustainability of organic dairying systems. Key words: Organic dairying, nutrient budget, nitrogen, potassium, phosphorus, soil fertility

Description: International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries calculate national inventories of their greenhouse gas emissions. The objective of the present study was to develop a country-specific (Tier II) methodology to calculate the inventory of N2O emissions from agricultural soils in Canada. Regional fertilizer-induced emission factors (EFreg) were first determined using available field experimental data. Values for EFreg were 0.0016 kg N2O-N kg-1 N in the semi-arid Brown and 0.008 kg N2O-N kg N-1 in the sub-humid Black soil zones of the Prairie region, and 0.017 kg N2O-N kg-1 N in the humid provinces of Quebec and Ontario. A function relating EFreg to the "precipitation to potential evapotranspiration" ratio was determined to estimate annual emission factors (EFeco) at the ecodistrict scale (≈ 150 000 ha) in all agricultural regions of Canada. Country-specific coefficients were also developed to account for the effect of several additional factors on soil N2O emissions. Emissions from fine-textured soils were estimated as being 50% greater than from coarse- and medium-textured soils in eastern Canada; emissions during winter and spring thaw corresponded to 40% of emissions during the snow-free season in eastern Canada; increased emissions from lower (wetter) sections of the landscape and irrigated areas were accounted for; emissions from no-till soils were 10% greater in eastern, but 20% lower in western Canada than from those under conventional tillage practices; emissions under summerfallow were estimated as being equal to those from soils under annual cropping. This country-specific methodology therefore accounts for regional climatic and land use impacts on N2O emission factors, and includes several sources/offsets that are not included in the Intergovernmental Panel on Climate Change (IPCC) default approach. Key words: Nitrous oxide, soils, greenhouse gases, inventory

Description: One of the key factors in phosphorus management is the P retention capacity (PRC) of the soil. In our previous study, we formulated several equations for estimating the phosphorus retention capacity of Manitoba soils. The objectives of the current study were to evaluate these equations using independent soil samples and to evaluate the influence of manure application on the predictive ability of these equations. Forty representative surface soil samples (20 soils with history of manure application and 20 without manure application history) were collected from across Manitoba. The P retention index (P150) and Langmuir adsorption maximum (Smax) were determined in the laboratory. The measured P retention capacities were then compared with those estimated using the formulated equations. Surprisingly, P150, which was obtained from a single measurement, was more robust than Smax that was obtained from at least 17 measurements as the equations provided a better estimate of P150 than Smax. Equations that were based on soil particle sizes (either percent clay or percent sand) provided poor estimates of soil PRC for the whole soil collection. However, when the soils were grouped on a pH basis, soil particle size worked better for soils with pH

Description: Rehabilitation of skid trails, temporary roads, and log landings is required for many harvested sites in British Columbia; however, more information is needed regarding practical methods to return these access areas to productive forest. Lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seedlings (1 + 0) were planted into (i) fully rehabilitated landings (burn-pile debris and topsoil incorporated), (ii) tilled landings, and (iii) unprepared portions of the adjacent cutblock. After two seasons of growth in the field, seedlings planted on fully rehabilitated landings were 38% larger, more robust, and exhibited 44% greater absolute growth and 22% greater relative growth rates, than seedlings planted in the adjacent cutblock. Seedlings planted on tilled landings were 33% smaller, and exhibited absolute growth rates 38% less, and relative growth rates 18% less, than seedlings planted in the adjacent cutblock. Seedlings planted in the cutblock exhibited higher ectomycorrhizal colonization rates. Our results indicate that tillage alone was not sufficient to fully rehabilitate these landings, but that incorporation of recovered topsoil and burn-pile debris produced an excellent growth substrate. This method, using materials found on site, can prevent a significant loss of land regenerating to productive second-growth forest.

Description: Clonal trials of Pinus radiata D. Don (radiata pine), representing two populations (or breeds), one selected for growth and form (GF) and the other selected for high wood density as well as growth and form (HD), were replicated on two low-altitude New Zealand sites: Tarawera (pumice soil, 38°08′S) and Woodhill (coastal dune, 36°42′S). The GF material comprised 33 pair-crosses (19 parents) × 10 clones, and the HD material comprised 19 single-pair crosses (35 parents) × 10 clones, with six ramets per clone per site. Diameter (DBH), two tree-form variables, and needle retention (NRA) were assessed 8 years after planting, and wood density (DEN), acoustic velocity, and collapse were assessed 9 years after planting. The site differences were generally expressed more strongly in the GF population. Estimated genetic parameters were mostly similar for the two breeds, except that genotypic correlation between DBH and DEN was apparently zero in the HD population. Estimated broad-sense heritabilities (H2) were generally markedly higher than narrow-sense heritability estimates (h2), except with DEN. Estimated between-site type-B clonal genotypic correlations were generally high (〉0.8) for wood properties. Overall, DBH showed adverse genetic correlations with wood properties. The Elite/Breed strategy appeared to be helpful in combating adverse genetic correlations.

Description: Permanent ground deformation is arguably the most severe hazard for continuous buried pipelines. This paper presents results from two pairs of centrifuge tests designed to investigate the differences in behavior of buried high-density polyethylene pipelines subjected to normal and strike-slip faulting. The tests results show that, as expected, the pipeline behavior is asymmetric under normal faulting and symmetric under strike-slip faulting. In the case of strike-slip faulting, the soil–pipe interaction pressure distribution is symmetric with respect to the fault. However, in the case of normal faulting, there is a pressure concentration close to the fault trace on the up-thrown side, with much lower soil–pipe interaction pressures at other locations on the pipe. The soil–pipe interaction force versus deformation relationship (i.e., the p–y relationship) was obtained based on the experimental data. The p–y relationships for both the strike-slip and normal faulting cases were also compared with the relationships defined within the American Society of Civil Engineers (ASCE) guidelines. It was found that, for the case of strike-slip faulting, the experimental p–y relationship is generally consistent with the ASCE guidelines. In contrast, the experimental p–y relationship is much softer than that defined by the ASCE guidelines for the normal faulting scenario.

Description: This paper examines the problem of harvest capacity planning at a tactical level. Annual capacity planning allows planners to determine the number of contractors to hire per period throughout the year and to define the duration of their contracts. In practice, this process usually involves the analysis of historical data regarding the operational use of capacity and aggregated demand forecast, the output of which then serves to plan harvest operations. Although this form of hierarchical planning reduces the complexity of the task, the decomposition into subproblems that must be successively resolved can lead to infeasibility or poor use of harvesting capacity. The specific problem addressed here resides in how one can consider the operational impact of harvesting decisions taken at the tactical level to ensure a plan’s feasibility at the operational level. We present a tactical planning process based on Schneeweiss’ generic hierarchical modeling approach. A computational experiment demonstrates how a tactical planning process is influenced by the input of the operational level anticipation model. The anticipation approach we propose appears to be a valid method to better integrate key operational-level decisions into tactical plans.

Description: Increased forest productivity has been obtained by improving resource availability through water and nutrient amendments. However, more stress-tolerant species that have robust site requirements do not respond consistently to irrigation. An important factor contributing to robust site requirements may be the distribution of biomass belowground, yet available information is limited. We examined the accumulation and distribution of above- and below-ground biomass in sweetgum ( Liquidambar styraciflua L.) and loblolly pine ( Pinus taeda L.) stands receiving irrigation and fertilization. Mean annual aboveground production after 4 years ranged from 2.4 to 5.1 Mg·ha–1·year–1 for sweetgum and from 5.0 to 6.9 Mg·ha–1·year–1 for pine. Sweetgum responded positively to irrigation and fertilization with an additive response to irrigation + fertilization. Pine only responded to fertilization. Sweetgum root mass fraction (RMF) increased with fertilization at 2 years and decreased with fertilization at 4 years. There were no detectable treatment differences in loblolly pine RMF. Development explained from 67% to 98% of variation in shoot versus root allometry for ephemeral and perennial tissues, fertilization explained no more than 5% of the variation in for either species, and irrigation did not explain any. We conclude that shifts in allocation from roots to shoots do not explain nutrient-induced growth stimulations.