bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution of on-farm and industrial composts to soil pH and enrichment in available nutrients and metals
Authors: Gagnon Bernard
Published: April 2011

Soil composition following addition of on-farm manure composts should be investigated for better utilization of these products in the field. An experiment was conducted to evaluate the contribution of several on-farm and industrial composts to soil pH and its enrichment in available major nutrients and metals (Cu, Zn, Fe, Mn). Materials were mixed at a rate of 200 mg N kg-1 with an Arago sandy loam (Humo-Ferric Podzol), and incubated in glass jars at 35°C for 13 wk. Composts from poultry litter (PL), vegetable residue (VR), wood shavings and dairy manure were among those that provided the highest levels of available N and P at the end of incubation. The vegetable residue compost also substantially increased the levels of Mehlich-3 Ca and Mg, but it was a poor source of K. Most dairy manure composts (DM) contributed to increase the soil exchangeable K. The industrial yard trimming compost (YT) largely increased soil pH and available N and Ca, but it was a very poor source of P and K. The spent mushroom compost (MU) also increased soil pH and Mehlich-3 Ca. In contrast to the major nutrients, on-farm composts had a limited impact on soil pH and on the available metal contents. This study indicates that the enrichment in major nutrients and metals of this acidic sandy loam and the relative contribution of the studied elements were mainly related to composted material sources and their degree of decomposition. Key words: Composting, farm manure, soil composition
Trends in dissolved phosphorus in Gray Luvisol soil profiles after forest harvest
Authors: Whitson I. R. , Abboud S. , Prepas E. E. , Chanasyk D. S.
Published: April 2011

Forest disturbances that increase P export from hillslopes will have negative consequences for site productivity and regional water quality. We studied P behavior in Gray Luvisols to understand the soil profile’s influence on P export from typical hillslopes of the Boreal Plain ecozone. We hypothesized that (1) P concentration is highest in upper horizons, (2) solution P is primarily in the dissolved and organic form, and (3) forest harvest will increase solution P concentration. We analyzed the soil solution, with emphasis on P, and determined P sorption properties of key soil horizons. Mean soluble reactive phosphorus concentration decreased with depth, ranging from 64 mg L-1 in the forest floor to 0.01 mg L-1 in the groundwater zone; solution P was mostly orthophosphate. Water soluble phosphorus decreased from 74 ± 9 to 41 ± 9 mg L-1 and extractable phosphorus was reduced in the forest floor only on two of four sampling occasions after harvest. Dissolved organic carbon may indirectly promote orthophosphate dominance in solution by complexing metal cations that would otherwise precipitate metal-P from solution. Gray Luvisols probably export P to soils lower on the hillslope catena, such as those of the Gleysolic and Organic Orders, both commonly associated with wetlands. Key words: Forest soil, phosphorus, orthophosphate, Gray Luvisol, biogeochemistry, sorption
Upscaling chamber-based measurements of N2O emissions at snowmelt
Authors: Pennock D. , Farrell R. , Desjardins R. , Pattey E. , MacPherson J. I.
Published: April 2011

One impediment to accurate national estimation of N2O is the difficulty in upscaling N2O measurements made at discrete points to larger field and regional scales. Our objective was to estimate N2O emissions during snowmelt in 2002 for a township (approximately 92 km2) near Laird, Saskatchewan. Chamber measurements were made at 12 sites in the township: four fields with canola (Brassica napus L.) residues, four with pea (Pisum sativum L.) residues, three with wheat (Triticum aestivum L.) residues, and one field that received cattle manure. Ten sampling chambers were used at each site, and N2O samples were made on 7 d during the snowmelt period (from 2002 Apr. 03 to Apr. 17). Cumulative N2O emissions during the 14 days of the snowmelt period differed between crop residue types: cumulative emissions from sites with wheat residues were 105.6 g N2O-N ha-1 and were significantly higher (P < 0.1) than those from fields with pea and canola residues (79.6 and 75.2 g N2O-N ha-1 respectively). The single manured site assessed had the highest cumulative emissions of 330.7 g N2O-N ha-1. The crop-specific emissions from the chamber-based measurements were multiplied by the area of each crop type in the township to calculate an area-weighted value for emissions. Cumulative emissions were 93.4 g N2O-N ha-1 for the chamber-based measurements. Water-filled pore space and soil temperature were not significantly correlated with cumulative emissions. Cumulative emissions from sites with fall nitrate levels below 8.0 kg ha-1 were consistently lower than those above this threshold. The emissions for the Laird township were well below the emissions calculated for most other studies in the Prairies and in central Canada. The lower emissions were probably due to low soil water contents and soil nitrate levels in the fall of 2001 and below normal snowfall in the winter of 2001-2002. This reinforces the importance in antecedent moisture conditions and soil N levels for modeling of emissions at snowmelt. Key words: Greenhouse gas, landscape-scale
Estimating carbon retention in soils amended with composted beef cattle manure
Authors: Helgason Bobbi L. , Larney Francis J. , Janzen H. Henry
Published: April 2011

Composted cattle manure is often used as a soil amendment to replenish nutrient pools and to supply a source of stable C. Compost composition affects the availability of nutrients and the stability of C following the addition of compost to soil. We investigated C mineralization in a loamy sand and a loam soil amended with nine composts, two fresh manures and alfalfa (Medicago sativa L.) hay at a target rate of 10 mg total C g-1 soil. Soils were incubated at 25°C for 168 d. There was a significant interaction between amendment and soil type on C mineralization but generally, the effect of soil texture on amendment decomposition was small. The composts were very dissimilar in composition and resulted in substantial differences in the amount of C retained in the soils (2-39% C added evolved as CO2). Total C evolved during the incubation period could be predicted from the NH4-N content and the NH4-N/NO3-N ratio of the composted manures (R2 = 0.91–0.93). Estimation of the C retained in soils amended with compost as a function of simple chemical properties of the compost provides an important tool for evaluating the effectiveness of compost as a soil amendment, helping to calculate net retention of C. Key words: Compost, mineralization, soil carbon, amendment
Management of Canadian prairie region grazed grasslands: Soil C sequestration, livestock productivity and profitability
Authors: Lynch D. H. , Cohen R. D. H. , Fredeen A. , Patterson G. , Martin R. C.
Published: April 2011

The GrassGro model (a computer simulation of management-induced changes in range and pasture forage and livestock productivity) was combined with spreadsheet analyses to estimate the influence of improved grazing practices on soil organic carbon (SOC), and farm profitability, across native rangelands and tame pastures of the southern Canadian Prairies. Improved practices included complementary grazing (CG) and reduced stocking density (RSD) on rangeland; and N fertilization (FERT), seeded grass/legumes grazed continuously (GLGC) or rotationally (GLGR), and RSD on tame pastures. The analysis was stratified into three ecoregions on the basis of similarities in climate and soil type. Averaged over 30 yr and ecoregions, SOC rates of gain through improved management were 5 (RSD) to 26 (CG) kg C ha-1yr-1 for rangelands, and 86 (RSD), 75 (GLGC), 62 (GLGR) and 222 (FERT) kg C ha-1yr-1 for tame pastures. Gains with FERT were considered largely negated by associated energy (C) costs, N2O emissions, and shifts in grassland species. The CG system alone improved net returns to the producer. The estimated potential combined SOC gain on prairie grazinglands (11.5 Mha) was 1.63 MMT CO2 yr-1 (or 0.465 MMT C yr-1), slightly less than the 1.70 MMT CO2 yr-1 currently emitted from agricultural soils in Canada. Key words: Soil carbon, GrassGro model, grazing management, rangeland, tame pasture
Phosphorus sorption capacity of alkaline Manitoba soils and its relationship to soil properties
Authors: Ige D V , Akinremi O O , Flaten D N , Ajiboye B. , Kashem M A
Published: April 2011

The establishment of the P retention capacity of soil in Manitoba is essential for effective management of P in the region. However, the methods for determining the P retention capacity for neutral to calcareous soils in the Eastern Prairies are not well developed. The objectives of this study were to determine the P retention capacity of Manitoba soils and to generate equations that relate these capacities to other soil properties. One hundred and fifteen archived surface soils were selected and their physico-chemical properties were measured. These soils were used to generate a single-point P adsorption index by equilibrating 2 g of soil in 20 mL of 0.01 M KCl solution containing either 150 (P150) or 400 (P400) mg P L-1. A subset of 26 of these soils was used for multipoint isotherms with P concentrations in the range of 0–1000 mg P L-1. The data obtained were fitted to the Langmuir isotherm and the adsorption indices were correlated with the various soil properties that were then used to developed predictive equations of the P retention capacity of the soil. The values of the adsorption index, P150, obtained from the single point adsorption study using 150 mg P L-1, ranged between 88 and 891 mg P kg-1, while that of P400 ranged between 100 and 1250 mg P kg-1. A better correlation was obtained between P150 and soil properties compared with P400. For the 26 soil subset, the adsorption indices, Smax1 to Smax 6, obtained from the Langmuir isotherm, ranged from 300 to 1330 mg kg-1. A good correlation was obtained between the single point index and the multipoint isotherm (r = 0.93). Hence, Smax for the 115 soils was estimated from the relationship between P150 and Smax 3 of the 26 soils. The best relationships between the adsorption parameters, P150 and Smax, and the soil properties were obtained with the sum of Mehlich-3 extractable Ca and Mg (R2= 0.66) and the sum of exchangeable Ca and Mg (R2= 0.64). Mehlich-3-Ca and -Mg each explained 56% of the variation, while clay content explained 40% of the variation in the P retention capacity of these soils. Unlike the widely reported influence of Al and Fe in acid soils, our study showed that the retention of P in Manitoba soils was influenced more by Ca and Mg and soil texture. Key words: Phosphorus, phosphorus retention capacity, phosphorus adsorption capacity, phosphorus sorption, single-point index
Binding of inorganic sulphate and phosphate in humid-climate soils measured using column leaching, equilibration and extraction methods
Authors: Kowalenko C. G.
Published: April 2011

The ability of soil samples to bind applications of inorganic sulphate and phosphate was examined in the laboratory using column leaching, solution equilibration and extraction methods. Eleven soil samples from the Fraser Valley of British Columbia with a range of soil characteristics and management histories were examined. Column leaching trials showed that sulphate was bound to soils, but not as strongly as phosphate. There was no evidence of significant sulphate binding during the equilibration trials but there was substantial native sulphate bound by the soils as shown by extraction of significant sulphate concentrations by bicarbonate extraction following equilibration. This shows that sulphate is not bound according to the traditional theory of adsorption, but other undefined mechanisms are involved. Both column leaching and equilibration results showed that the samples studied varied considerably in their native phosphate retention attributes, with some samples releasing no phosphate and others releasing considerable phosphate into the water treatments. Equilibration trials showed that some of the soils bound large quantities of phosphate resulting in no phosphate in the soil solution whereas others bound much less resulting in significant phosphate concentrations in the soil solution. Phosphate binding followed the Freundlich equation in eight of the samples, the Tempkin equation in one sample and a direct linear relationship in two samples. The Langmuir equation fitted most of the samples that had followed Freundlich equation reasonably well, but did not fit the other samples. This showed that determination of the maximum amount of phosphate that can be bound by the sample (i.e., P saturation) using the Langmuir equation cannot be used for all humid-climate soils of British Columbia. Two alternate direct measurements are proposed to determine the potential risk of phosphate in soils to contaminate water: amount of phosphate released during equilibration with water (native unbound phosphate) and amount of phosphate bound during equilibration with a low (approximately 25 mg P kg-1) phosphate solution (potential for the soil to bind applied P). These results show that sulphate and phosphate binding mechanisms by coastal British Columbia soils are not well understood. The nature of the binding mechanisms needs to be determined to develop and interpret soil analyses for agronomic and environmental purposes. Key words: Sulphate binding, phosphate binding, P saturation, soil solution P
Spatial variability of soil properties and 2,4-D sorption in a hummocky field as affected by landscape position and soil depth
Authors: Gaultier Jeanette , Farenhorst Annemieke , Crow Gary
Published: April 2011

Since pesticide fate and leaching models increasingly incorporate spatial variability, the objective of this study was to quantify the variability of soil properties and 2,4-D sorption within a hummocky field as affected by landscape position and soil depth. Seventy-two soil cores collected at 5-m intervals along a transect were segmented by soil horizon (A, B and C) and landscape position (upper, mid, lower and depression). As expected, soil organic carbon content significantly decreased, and soil pH and soil carbonate content significantly increased with soil depth, while clay content was significantly greater in the B horizon than the A and C horizon. Soils from the depressional area generally had higher soil organic carbon content, soil carbonate content, clay content and soil pH than soil samples from other slope positions. The sorption of 2,4-D by soil was positively correlated with soil organic matter content and negatively correlated with soil carbonate content. These soil properties and herbicide sorption varied along the transect and with soil depth. Regardless of whether or not the landscape was segmented by landscape position, for both the A and C horizon, predictions of 2,4-D sorption by soil were generally good using simple regression models that contained soil organic carbon content and carbonate content as the only parameters. However, for the B horizon, the prediction of 2,4-D sorption by soil was very poor when all sampling points along the transect were considered, but greatly improved for the mid- and depressional slope positions when soils were segmented by landscape position. We conclude that segmentation by slope position could be a useful additional tool when predicting pesticide fate and leaching at the large-scale. As well, the negative association between soil carbonate content and 2,4-D sorption warrants further attention as a large portion of Canadian agriculture encompasses calcareous soils. Key words: 2,4-D, sorption, soil organic carbon, carbonates, landscape position, soil depth
A method for measuring above- and below-ground C stocks in hillside landscapes
Authors: Monreal C. M. , Etchevers J. D. , Acosta M. , Hidalgo C. , Padilla J. , López R. M. , Jiménez L. , Velázquez A.
Published: April 2011

Information on C stocks in agriculture and forest ecosystems in hillside landscapes is limited. The objective of this study was to develop and test field methods to measure above- and below-ground C stocks in hillside landscapes. Above-ground biomass in agricultural system was determined by measuring weight of residues left after crop harvest. In degraded secondary forests, tree biomass was estimated using allometric equations developed from in situ measurements. Herbs + bushes and litter dry weight were measured in two 0.25-m2 quadrats located within one 100-m2 treed plots. Carbon stocks were determined after chemical analysis of plant tissue and soil samples by dry combustion. Geo-referenced cores were taken inside a 1-m-diameter soil sampling clock that allows for spatial and temporal monitoring of soil C changes. The clock was marked with 12 divisions to establish the exact location of present and future sampling points. The below-ground fraction of C (mineral soil and fine roots) amounted to nearly 95% of the total C stock in agricultural systems and between 57 and 82% in the case of forest systems. Soil C stocks in hillside agricultural soils were higher than those found in forested soils with 70% of the C stored below-ground residing in the 0–45 cm of soil. The field method detected differences in C stocks in pools associated with various vegetations and soils in hillside ecosystems. Key words: Soil carbon, belowground carbon, sampling clock, hillside agriculture, Mexico
Economic constraints to the adoption of carbon farming
Authors: Pretty Jules , Farage Peter , Ball Andrew
Published: April 2011

The potential for sustainable agricultural practices to sequester C is substantial. The economic feasibility and competitiveness of soil C sequestration depends on the opportunity cost per tonne of C stored. The key issue is whether the cost is competitive with alternative methods of reducing greenhouse gas emissions. The high spatial variability in land productivity means that the soil characteristics are important when designing public policies to address this issue. Empirical evidence suggests that the opportunity cost per tonne of C stored can be as low as US$10 to US$25 t-1 (Can$12–30), but that for the majority of temperate agriculture it exceeds US$50 t-1 (Can$60). The final monetary value placed on a tonne reduction of C will emerge either from the establishment of a fully functioning market or from government payment schemes. Estimates of the value of stored C have ranged from US$100 t-1 (Can$120) to a low of less than US$5 t-1 (Can$6). Current evidence suggests a likely price in the lower region of this range. Key words: Carbon farming, carbon sequestration, soil organic carbon, soil sustainability
Effect of crop rotations on NO3 leached over 17 years in a medium-textured Brown Chernozem
Authors: Campbell C. A. , Selles F. , De Jong R. , Zentner R. P. , Hamel C. , Lemke R. , Jefferson P. G. , McConkey B. G.
Published: April 2011

High NO3 concentration in drinking water can be a health hazard, but properly fertilized rotations containing cereals and pulses or perennial grasses reduce the risk of NO3 leaching. Over fertilization, and sometimes under fertilization, frequent summer fallowing, and use of legume green manure may increase the risk of NO3 leaching in subhumid areas. We used a crop rotation study, initiated in 1987 on a medium-textured Brown Chernozem at Swift Current, Saskatchewan, to determine the influence of cropping frequency, legume green manure, wheat class and grass hay crop on NO3-N leached beyond the rooting depth of cereals (1.2 m) after 17 yr. Nitrate distribution in the soil to 2.4 m was measured in 1987 and again in 2003. All rotations received N and P fertilizer based on soil tests, and were generally managed using no-tillage. The period had 4% more precipitation than the long-term average (367 mm) with 5 yr exceeding the average by >13%. A comparison of NO3-N content below 1.2 m depth in 1987 and 2003 showed no significant (P < 0.05) leaching has occurred, although the legume (Lens culinaris L.) green manure-wheat-wheat (Triticum aestivum L.) system showed evidence it may eventually leach NO3. Contrary to expectations, continuous-wheat, because of higher N applied and possibly because net N mineralization is small under no-tillage, tended to leach more NO3 than fallow-containing rotations (P = 0.09). Crested Wheatgrass (Agropyron cristatum L. Gaertn) reduced NO3 content to 2.4 m because it is a perennial with deep and extensive roots. There was no effect of wheat class on the amount of NO3 leached. Key words: Cropping frequency, wheat class, lentil green manure, crested wheatgrass
Increase in phosphorus concentration of a clay loam surface soil receiving repeated annual feedlot cattle manure applications in southern Alberta
Authors: Joann K. Whalen Chi Chang, , Hao Xiying
Published: April 2011

Migration of P from soils to water resources poses a risk of surface water eutrophication, and increase in P concentration in soils through manure or fertilizer addition would exace rbate this problem. Investigating the rate of increase in P concentration of surface soil receiving livestock manure is crucial to the development of best manure management strategies and prevention of eutrophication of aquatic systems. In this study, the changes in P concentrations of surface soils (0- to 15-cm depth) receiving 25 annual manure applications at rates of 0, 30, 60 and 90 Mg ha-1 yr-1 under non-irrigated conditions and at rates of 0, 60, 120 and 180 Mg ha-1 yr-1 under irrigated conditions were examined. The soil test P (STP) and total P (TP) of the surface soil increased with the TP through manure application over a 25-yr period. The STP pool was about 38% of the soil TP pool, similar to ratios of STP to TP in feedlot cattle manure. While the high proportion of STP to TP could be beneficial for crop production, it could also increase the potential for P losses from these soils through runoff and leaching. The changes in TP and STP concentrations of the surface soil were modelled with an expone ntial rise to maximum function:

TP = 0.69 + 5.06 (1 − e(−0.087x))

and

STP = 0.029 + 2.21 (1 − e(−0.082x))

where x is the cumulative TP applied. Although the model was developed for a specific soil and type of manure, it could be adapted to other soils or manure sources by adjusting the model coefficients for the particular soil and/or manure type. These adjustments would not require as extensive a data set as was required to develop the original model. This model could be used to determine the amount of TP that could be applied for a given critical STP. Producers, regulatory agencies, planners, and extension specialists could also use this model to make decisions on manure P management. Key words: Long-term cattle manure application, total phosphorus, available phosphorus, rate of accumulation, non-irrigated and irrigated cropping
Nitrogen supply of a Dark Brown Chernozem soil and its utilization by wheat
Authors: Soon Y K , Brandt S A , Malhi S S
Published: April 2011

Environment and management effects on the N supply to crops are not well understood. We assessed the influence of tillage system (conventional tillage or no-till), N fertilizer (0 or 60 kg N ha-1) and year on N sources and supply of a Dark Brown Chernozem loam soil, and N utilization by spring wheat (Triticum aestivum L.) in 2 yr. The main N source was mineralized N; only 14–23% of wheat N was derived from fertilizer, and non-exchangeable ammonium made no measurable contribution. Soil NO3 and exchangeable NH4 content at sowing and net N mineralization during the growing season (Nmin) were influenced more by year than by N addition and tillage. Nmin was 90–100 kg N ha-1 in 1999, a moist growing season but only 21–39 kg N ha-1 in 2000, a drier year. In both years, soil inorganic N to 60 cm at sowing averaged about 60 kg N ha-1 of which half was N mineralized since the previous harvest. Year accounted for 65–81% of the variation in N uptake. Fertilization increased N uptake and wheat yields, especially in 2000, but fertilization and tillage had no effect on post-heading N uptake and N translocation. Nitrogen use efficiency (NUE) and N recovery were lower with N applied and not affected by tillage. Our study indicated that available N was affected more by environment than management. In dry conditions, when Nmin is low, N application may be more effective in increasing yield and N uptake than in wet years, an observation that may merit further attention. Key words: Available N, N mineralization, N recovery, N use efficiency, non-exchangeable ammonium, tillage
A proposed method for rapid and economical extraction of petroleum hydrocarbons from contaminated soils
Authors: Siddique Tariq , Rutherford P. Michael , Arocena Joselito M , Thring Ronald W
Published: April 2011

Petroleum hydrocarbons (PHC) are common soil contaminants. A number of methods have been used to extract PHCs from soil prior to quantification by gas chromatography (GC). These methods often require long extraction times and expensive, specialized equipment. A shaking method was assessed for simple, rapid removal of PHCs from contaminated soils. Shaking spiked and aged contaminated soils for 4 h with acetone:hexane (1:1) at a soil:solvent ratio of 1:30 (g:mL) recovered 74 to 108% of PHC, compared with a Soxhlet extraction, yielding a good correlation (4 h = −93.7 + 0.99 Soxhlet r = 0.99, P < 0.001). Preliminary results show that this 4-h procedure has potential for the quick, inexpensive extraction of PHCs from contaminated soils. Key words: Petroleum hydrocarbons, soil analysis, extraction method, gas chromatography, Soxhlet extraction
Assessing a new soil carbon model to simulate the effect of temperature increase on the soil carbon cycle in three eastern Canadian forest types characterized by different climatic conditions
Authors: Larocque Guy R. , David Paré Robert Boutin, , Robitaille Gilles , Lacerte Valérie
Published: April 2011

The predictive capacity of process-based models on the carbon (C) cycle in forest ecosystems is limited by the lack of knowledge on the processes involved. Thus, a better understanding of the C cycle may contribute to the development of process-based models that better represent the processes in C cycle models. A new soil C model was developed to predict the effect of an increase in the temperature regime on soil C dynamics and pools in sugar maple (Acer saccharum Marsh.), balsam fir [Abies balsamea (L.) Mill.] and black spruce [Picea mariana (Mill.) B.S.P.] forest types in Eastern Canada. Background information to calibrate the model originated from the experimental sites of the ECOLEAP project as well as from a companion study on laboratory soil incubation. Different types of litter were considered in the model: foliage, twigs, understory species, other fine detritus and fine roots. A cohort approach was used to model litter mineralization over time. The soil organic C in the organic (F and H) and mineral layers (0–20 cm) was partitioned into active, slow and passive pools and the rates of C transfer among the different pools and the amount of CO2 respired were modelled. For each forest type, there was a synchrony of response of the C pools to soil temperature variation. The results of the simulations indicated that steady state conditions were obtained under current temperature conditions. When mean annual soil temperatures were gradually increased, the litter and active and slow C pools decreased substantially, but the passive pools were minimally affected. The increase in soil respiration resulting from a gradual increase in temperature was not pronounced in comparison to changes in mineralization rates. An increase in litter production during the same period could contribute to reducing net C losses. Key words: Soil organic matter, litter, soil respiration, climate change
Modeling carbon sequestration with CO2Fix and a timber supply model for use in forest management planning
Authors: Neilson E. T. , MacLean D. A. , Arp P. A. , Meng F. -R. , Bourque C. P-A. , Bhatti J. S.
Published: April 2011

Carbon (C) dynamics and forest management have become integrated in recent years, largely due to the Kyoto Protocol stipulating that forest C changes may be accountable in an emissions framework. A C stock modeling framework for forest managers is introduced in this paper. Empirical growth and yield models are used to develop sustainable timber supply for forest companies. These models use linear programming to solve the complex mathematical problem of timing and allocation of forest harvest and silviculture interventions. In this paper, we evaluated the effects of “business as usual”forest management versus management objectives to maximize C sequestration. Goal programming was used to minimize the deviation of two goals for C forest management: maximizing C in the forest, and maximizing the return on investment (net present value of forest timber products). Species-specific wood-to-C content conversion factors were used to parameterize the amount of C in forest stands on Canadian Forces Base Gagetown forest lands in New Brunswick, Canada. Goal programming reduced the loss of revenue associated with increasing C stocks in the forest. Partial harvesting and high valued end-products tended to increase C stocks and provided a higher return on investment in the simulations. Key words: Carbon stock modeling framework, forest, goal programming, partial harvesting, timber supply
Modeling snowpack and soil temperature and moisture conditions in a jack pine, black spruce and aspen forest stand in central Saskatchewan (BOREAS SSA)
Authors: Jagtar Bhatti Vincent Balland, , Mark Castonguay Ruth Errington, , Arp Paul A.
Published: April 2011

Impacts of climate change on above- and below-ground heat and moisture conditions were modeled so that other impacts on, e.g., local carbon (C) and C-based pools for nutrients and pollutants such as Hg can be predicted reliably. This paper shows how the 199–-2003 data for the jack pine (jp; Pinus banksiana Lamb.), black spruce (bs; Picea mariana) and aspen (ta; Populus tremuloides) sites of the Southern Study Area of the BOREAS project were used to estimate some of the hydrothermal soil responses at these locations to daily variations in precipitation and air temperature. This was done by initializing and calibrating a forest hydrology model that has the capacity to simulate flow and retention of moisture and heat, as modified by canopy closure, ground cover, forest-floor depth, and soil composition. The calculations and data revealed strong but predictable site-specific differences in soil temperature and frost penetration (jp: 1–2 m > ta: 0.5–1 m > bs: 0–0.5 m), in soil moisture freezing (ta < bs < jp), and in moisture retention (jp < ta < bs). Apart from daily weather, these differences depended on soil texture (loamy/sandy texture impeded/encouraged soil freezing, respectively), and on the thermal insulation and moisture retention of the combined forest floor, moss and lichens layers (ta < jp < bs). Key words: Jack pine, aspen, black spruce, soil moisture, soil temperature, frost penetration, snowpack, boreal conditions
A proposed approach to estimate and reduce net greenhouse gas emissions from whole farms
Authors: Janzen H H , Angers D A , Boehm M. , Bolinder M. , Desjardins R L , Dyer J. , Ellert B H , Gibb D J , Gregorich E G , Helgason B L , Lemke R. , Massé D. , McGinn S M , McAllister T A , Newlands N. , Pattey E. , Rochette P. , Smith W. , VandenBygaart A J , Wang H.
Published: April 2011

Greenhouse gas emissions from farms can be suppressed in two ways: by curtailing the release of these gases (especially N2O and CH4), and by storing more carbon in soils, thereby removing atmospheric CO2. But most practices have multiple interactive effects on emissions throughout a farm. We describe an approach for identifying practices that best reduce net, whole-farm emissions. We propose to develop a “Virtual Farm”, a series of interconnected algorithms that predict net emissions from flows of carbon, nitrogen, and energy. The Virtual Farm would consist of three elements: descriptors, which characterize the farm; algorithms, which calculate emissions from components of the farm; and an integrator, which links the algorithms to each other and the descriptors, generating whole-farm estimates. Ideally, the Virtual Farm will be: boundary-explicit, with single farms as the fundamental unit; adaptable to diverse farm types; modular in design; simple and transparent; dependent on minimal, attainable inputs; internally consistent; compatible with models developed elsewhere; and dynamic (“seeing”into the past and the future). The Virtual Farm would be constructed via two parallel streams - measurement and modeling - conducted iteratively. The understanding built into the Virtual Farm may eventually be applied to issues beyond greenhouse gas mitigation. Key words: CO2, N2O, CH4, agroecosystems, models, climate change
Canadian agricultural land-use and land management data for Kyoto reporting
Authors: Huffman T. , Ogston R. , Fisette T. , Daneshfar B. , L. White P-Y. Gasser, , Maloley M. , Chenier R.
Published: April 2011

The land use and management data requirements for assessing, monitoring and reporting on the impact of agricultural production practices on the environment, especially in a country as large as Canada, are considerable. In view of the fact that environmental assessments are a relatively new phenomenon, data collection activities targeted toward these needs are not widespread. As a result, we find it necessary to acquire and integrate a variety of data sources with differing time lines, spatial scales and sampling frameworks. This paper uses our current activities with respect to Kyoto reporting as a focus to present and discuss the types of data required and the spatial analysis and integration procedures being developed to provide them. The essential data for this activity include the area of crop and land use types, land use changes since 1990, farm and land management practices and biomass production. The spatial framework selected for national analysis is the Soil Landscapes of Canada, and the primary existing data sources are the Census of Agriculture, sample-derived yield estimates and satellite-based land cover products. These are supplemented with detailed, multi-season, multi-year satellite image interpretations conducted at an ecologically and statistically stratified sample of sites across the country. The use of these data in preparing an account of greenhouse gas sources and sinks identified a number of gaps and problems, and a brief outline of future work designed to improve the data inputs is presented. Key words: Kyoto reporting, data integration, land use and management, greenhouse gases, carbon sequestration
Towards accurate measurements of soil organic carbon stock change in agroecosystems
Authors: VandenBygaart A J , Angers D A
Published: April 2011

In response to Kyoto Protocol commitments, countries can elect agricultural carbon sinks to offset emissions from other sectors, but they need to verify soil organic carbon (SOC) stock change. We summarize issues we see as barriers to obtaining accurate measures of SOC change, including: soil depth, bulk density and equivalent soil mass, representation of landscape components, experimental design, and the equilibrium status of the SOC. If the entire plow depth is not considered, rates of SOC storage under conservation compared with conventional tillage can be overstated. Bulk density must be measured to report SOC stock on an area basis. More critical still is the need to report SOC stock on an equivalent mass basis to normalize the effects of management on bulk density. Most experiments comparing SOC under differing management have been conducted in small, flat research plots. Although results obtained from these long-term experiments have been useful to develop and validate SOC prediction models, they do not adequately consider landscape effects. Traditional agronomic experimental designs can be inefficient for assessing small changes in SOC stock within large spatial variability. Sampling designs are suggested to improve statistical power and sensitivity in detecting changes in SOC stocks over short time periods. Key words: Soil organic carbon change, agroecosystems, experimental design, sampling depth
Topsoil replacement depth and organic amendment effects on plant nutrient uptake from reclaimed natural gas wellsites
Authors: Zvomuya Francis , Larney Francis J , Akinremi Olalekan O , Lemke Reynald L , Klaassen Vasile E
Published: April 2011

Sustained plant nutrient a vailability on reclaimed wellsites is critical to the successful restoration of crop productivity. This study evaluated topsoil replacement depth (TRD) (0, 50, 100, and 150% of mandatory TRD) and organic amendment [beef cattle feedlot manure, compost derived from straw-bedded cattle feedlot manure, wheat (Triticum aestivumL.) straw, alfalfa (Medicago sativaL.) hay, and unamended control] effects on nutrient uptake by a wheat crop at three abandoned gas wellsites in south-central Alberta. Grain N uptake increased by 0.055 kg ha-1 for each percent increase in TRD, reflecting the corresponding linear increase in grain N concentration. Low carbon to nitrogen (C:N) ratio amendments, particularly compost and alfalfa, were the most effective for improving grain N concentration and uptake. Conversely, N concentration and uptake were lowest for the high C:N (53:1) wheat straw amendment. Reclamation programs should, therefore, consider incorporation of the low C:N alfalfa or compost in order to safeguard against N deficiency in the first 1–2 yr following reclamation. Our results also show that high P amendments, such as manure and compost, are better choices for improving P uptake by spring wheat. These results emphasize the importance of topsoil replacement and amendment quality (C:N ratio and P concentration) in ensuring adequate N and P supply in the 1–2 yr following reclamation. Based on this, compost appears to be the best single amendment for ensuring enhanced uptake of both N and P on reclaimed wellsites in the short term. Key words: Topsoil replacement; organic amendments; reclamation; nitrogen; phosphorus
Soil nutrient stratification and uptake by wheat after seven years of conventional and zero tillage in the Northern Grain belt of Canada
Authors: Lupwayi N Z , Clayton G W , O’Donovan J T , Harker K N , Turkington T K , Soon Y K
Published: April 2011

The distribution of NaHCO3-extractable nitrate-N, ammonium-N, phosphorus (P) and potassium (K) with soil depth (0 to 20 cm in 5-cm increments) at Fort Vermilion (58°23′N 116°02′ W), Alberta, was described in the 7th and 8th years of conventional and zero tillage following placement of red clover (Trifolium pratense) green manure (GM), field pea (Pisum sativum), canola (Brassica rapa) and monoculture wheat (Triticum aestivum) residues. Soil nitrate-N concentrations under zero tillage were greater than those under conventional tillage in the 0–5 cm soil layer, below which the concentrations were similar. Ammonium-N and K concentrations followed a similar pattern. However, soil P concentrations were usually not different between tillage systems in the 0–5 cm soil layer, but the concentrations decreased more under zero tillage than under conventional tillage at lower depths. A notable exception for soil phosphate was under canola residues, where the concentration was greater under zero tillage than under conventional tillage at all depths. Uptake of N, P or K by a subsequent wheat crop was usually greater (though not always significantly) under zero tillage than under conventional tillage, and there were no interactions between tillage and crop residue. Therefore, differences in nutrient stratification between the two tillage systems did not translate into differences in wheat nutrient uptake. Key words: Conservation tillage, crop rotation, nutrient uptake, soil nitrogen, soil phosphorus, soil potassium
Distribution and persistence of DDT in soil at a sand dune-marsh environment: Point Pelee, Ontario, Canada
Authors: Crowe Allan S , Smith James E
Published: April 2011

DDT was applied at Point Pelee, Ontario, Canada, between 1948 and 1970 for mosquito control in recreational areas and pest control in former agricultural areas. Recent soil sampling programs produced 275 analyses enabling a statistical comparison of DDT concentrations with land use areas, soil conditions, and hydrologic characte ristics. Concentrations of ΣDDT ranged over several orders of magnitude, with the highest concentrations (maximum 316 000 ng g-1) in former agricultural areas and the lowest concentrations in the natural sand dunes (maximum of 116 ng g-1). DDT is undergoing degradation at Point Pelee along two pathways. DDT is transformed aerobically to DDE within the sandy soils exhibiting average %DDT, %DDE and %DDD of 40%, 55%, and 5% of ΣDDT, respectively. DDT is transformed anaerobically to DDD and DDE within the marsh and flooded soils averaging 14% DDT, 44% DDE, and 42% DDD, respectively. The half-lives for the transformation of DDT to DDE within the well-drained and aerobic sandy soils at Point Pelee are highly variable and were estimated to range from 20 to 50 yr. Given the high concentrations of ΣDDT at Point Pelee and the long half-life, it is expected that DDT will remain at concentrations of concern for many decades. Key words: DDT, persistence, degradation rates, concentrations, sandy soil, marshy soil
Ammonia emissions from land-applied beef cattle manure
Authors: McGinn S. M. , Sommer S. G.
Published: April 2011

Ammonia (NH3) is emitted in vast quantities from exposed livestock manure. The volatilisation of NH3 from livestock manure is a loss in valuable nitrogen in land-applied manure that could otherwise be used for crop production. Ammonia loss to air is also affiliated with environmental problems when it is deposited to the surrounding landscape. The goal o f this study was to quantify the effect of managing beef cattle manure on NH3 emissions of land-applied manure. Three trials were conducted where beef feedlot manure was applied. The NH3 losses were measured from field plots (90 or 160 m2) using acid traps (passive flux samplers). Immediately after applying manure, irrigating with 6 mm of water reduced NH3 loss by 21–52% while tillage (to 15 cm depth) reduced the loss by 76–85% compared with leaving the manure spread on the soil surface. Piled manure that was applied to the land lost 27% less NH3 than did manure taken directly from the pen. There was little NH3 lost from compost that was applied to land since the applied available-N was very low relative to the pen and piled manure. Our study shows that management of livestock manure has a direct impact on NH3 loss to air. It follows that significant reduction in NH3 volatilisation can benefit agriculture and reduce agriculture’s impact on the environment. Key words: Ammonia, manure, tillage, irrigation, compost, feedlot
Distribution of organic carbon in the stable soil humic fractions as affected by tillage management
Authors: Murage Evah W , Voroney Paul
Published: April 2011

Soil humus comprises a large and stable pool of soil organic matter (SOM); hence a better understanding of the fate of C in soil humic fractions can provide valuable information for the development of alternative tillage practices that will lead to long-term soil C sequestration. We used δ13C techniques to investigate the effects of tillage on the dynamics of native (C3–C) and corn derived C (C4–C) in fulvic acid (FA), humic acid (HA) and humin fractions. Humic substances were extracted from soils cropped to corn for 11 yr and managed under either conventional (CT) or no-tillage (NT), and from a conventionally tilled soil under > 55 yr of tobacco/rye rotation. No-tillage resulted in higher proportions of C4–C in the upper 5 cm and generally lower C4–C proportions below 5 cm than CT. Up to 31, 27 and 34% of C4–C were assimilated into FA, HA and humin fractions, respectively, indicating that even the humin fraction, often described as passive, old or resistant, acted as a sink of recently added C, and that it is heterogeneous with some of its components being young. Recovery of large proportions of C3–C in the humic fractions demonstrated their importance in the long-term stabilization of SOM. Within each sampling depth, there were no unique differences in the distribution of C3–C among the three humic fractions, suggesting similar turnover of C3–C in all the fractions. Therefore, there was no unique active fraction corresponding with the concept of C pools with defined turnover characteristics used in models of SOM turnover. Key words: Soil humic fractions, corn derived C, native C, δ13C techniques, tillage practices
Influence of aggregate architecture and minerals on living habitats and soil organic matter
Authors: Monreal C. M. , Kodama H.
Published: April 2011

We used an integrated approach to determine the effects of soil particle architecture and minerals on living habitats and soil organic matter (SOM). Macroaggregate (> 250 µm), microaggregate 1 (50–250 µm), and microaggregate 2 (< 50 µm) fractions of adjacent forested and cultivated Gleysolic soil were obtained by wet sieving. The forested site was used as a reference to evaluate the effects of cultivation on soil particle architecture. Aggregates and respective clay fractions were characterized using optical, chemical, physical and microbial methods. Microaggregates 1 had primary particles with the largest mean equivalent spherical diameter (ESD) and void volume of all aggregate fractions. These physical characteristics were paralleled by the highest SOM and microbial biomass content, and number of microorganisms. Cultivation increased the weathering of primary particles and SOM loss, and decreased the content of microbial pools, suggesting deteriorated living habitats. Soil organic C content in aggregates correlated significantly with the amount of ammonium oxalate extractable Al, chloritized vermiculite, and vermiculite, and was inversely associated with the total clay content. The mean ESD of primary particles and expandable phyllosilicates of aggregates influenced living habitats by supplying substrates, and providing different void and protective space for soil microorganisms.

Key words: Aggregate, mean equivalent spherical diameter, bacteria, fungi, actinomycetes, microbial biomasss, organic carbon, vermiculite, non-crystalline inorganic soil components