bluuebunny/crossref_metadata_2025 huggingface dataset:
N2O fluxes in soils of contrasting textures fertilized with liquid and solid dairy cattle manures
Authors: Rochette Philippe , Angers Denis A , Chantigny Martin H , Gagnon Bernard , Bertrand Normand
Published: April 2011

Manure is known to increase soil N2O emissions by stimulating nitrification and denitrification processes. Our objective was to compare soil-surface N2O emissions following the application of liquid and solid dairy cattle manures to a loamy and a clay soil cropped to silage maize. Manures were applied in 2 consecutive years at rates equivalent to 150 kg total N ha-1 and compared with a control treatment receiving an equivalent rate of synthetic N. Soil-surface N2O fluxes, soil temperature, and soil water, nitrate and ammonium contents were monitored weekly in manured and control plots. From 60 to 90% of seasonal N2O emissions occurred during the first 40 d following manure and synthetic fertilizer applications, indicating that outside that period one or several factors limited N2O emissions. The period of higher emissions following manure and fertilizer application corresponded with the period when soil mineral N contents were highest (up to 17 g NO3−-N m-2) and water-filled pore space (WFPS) was greater than 0.5 m3 m-3. The absence of significant N2O fluxes later in the growing season despite high WFPS levels indicated that the stimulating effect of organic and synthetic N additions on soil N2O production was relatively short-lived. Fertilization of silage maize with dairy cattle manure resulted in greater or equal N2O emissions than with synthetic N. This was observed despite lower overall soil mineral N contents in the manured plots, indicating that other factors affected by manure, possibly additional C substrates and enhanced soil respiration, resulted in greater denitrification and N2O production. Silage maize yields in the manured soils were lower than those receiving synthetic N, indicating that the N2O emissions per kilogram of harvested biomass were greater for manures than for synthetic N. Our results also suggest that the main source of N2O was nitrification in the loam and denitrification in the clay soil. There was no clear difference in N2O emissions between liquid and solid manures. The variable effects of liquid and solid manure addition reported in the literature on soil N2O emissions likely result from the variable composition of the manures themselves as well as from interactions with other factors such as soil environment and farming practices. A better characterization of the availability of manure C and N is required to assess the impact of manure application on soil N2O emissions under field conditions. Key words: Greenhouse gases, N2O, maize, manure
Nitrous oxide emissions and soil mineral nitrogen status following application of hog slurry and inorganic fertilisers to acidic soils under forage grass
Authors: Mkhabela M S , Gordon R. , Burton D. , Madani A. , Hart W.
Published: April 2011

Field application of livestock slurry often results in higher nitrous oxide (N2O) emissions than inorganic fertiliser, because slurry contains large amounts of available N and C, and when applied it increases soil water content, thus enhancing denitrification. This study evaluated the impact of hog (Sus scrofa) slurry and inorganic fertilisers on N2O emissions and soil inorganic N. Three short-term (3 wk) field experiments were conducted during summer 2005 on two contrasting acidic soils seeded to forage grass. Treatments included hog slurry (Slurry) at 126 kg N ha-1, potassium nitrate (Nitrate) at 120 kg N ha-1, ammonium sulphate (Ammonium) at 120 kg N ha-1, Carbon (Dextrose) at 500 kg ha-1 and an unamended control (Control). Potassium nitrate increased (P< 0.05) cumulative N2O losses compared with the other treatments. Emissions of N2O from Slurry and Ammonium were similar, but higher than from Dextrose and Control, which were similar. Soil NH4+-N contents for Slurry and Ammonium treatments were generally similar but higher than for the other treatments, particularly during the first and second sampling dates. Soil NO3−-N contents, meanwhile, were higher with the Nitrate treatment compared with the other treatments, especially at the first sampling date. These results imply that N2O production in these acid soils was limited by NO3-availability. Therefore, N2O emissions from these soils can be minimised by using ammonium-based fertilisers including hog slurry rather than nitrate-based fertilisers. Key words: Acidic soils, hog slurry, mineral fertiliser, soil nitrogen, N2O emissions
Spring thaw and growing season N2O emissions from a field planted with edible peas and a cover crop
Authors: Pattey Elizabeth , Blackburn Lynda G , Strachan Ian B. , Desjardins Ray , Dow Dave
Published: April 2011

Nitrous oxide emissions are highly episodic and to accurately quantify them annually, continuous measurements are required. A tower-based micrometeorological measuring system was used on a commercial cattle farm near Cô teau-du-Lac, (QC, Canada) during 2003 and 2004 to quantify N2O emissions associated with the production of edible peas. It was equipped with an ultrasonic anemometer and a fast-response closed-path tunable diode laser. Continuous measurements of N2O fluxes were made during the spring thaw following corn cultivation in summer 2002, then during an edible pea growing season, followed by cattle manure application, cover crop planting and through until after the next spring ploughing. The cumulative N2O emissions of 0.7 kg N2O-N ha-1 during the initial snowmelt period following corn harvest were lower than expected. Sustained and small N2O emissions totalling 1.7 kg N2O-N ha-1 were observed during the growing season of the pea crop. Solid cattle manure applied after the pea harvest generated the largest N2O emissions (1.9 kg N2O-N ha-1 over 10 d) observed during the entire sampling period. N2O emissions associated with the cover crop in the fall were mostly influenced by manure application and totalled 0.8 kg N2O-N ha-1. For the subsequent spring thaw period, N2O emissions were 0.8 kg N2O-N ha-1. This represents approximately 15% of the annual emissions for the edible pea-cover crop system, which totalled 5.6 kg N2O-N ha-1 over the measuring periods. There was little difference in spring thaw N2O emissions between the two growing seasons of corn and edible pea-cover crop. Key words: Nitrous oxide emissions, legumes, snowmelt, dairy manure, tunable diode laser, flux tower
Effects of coarse fragment content on soil physical properties, soil erosion and potato production
Authors: Chow T L , Rees H W , Monteith J O , Toner P. , Lavoie J.
Published: April 2011

Most potato (Solanum tuberosum L.) production in northeastern America is on till soils with an abundance of stones. Stone picking has removed many coarse fragments to a point that it might be detrimental to soil quality. This study was to assess the impacts of coarse fragment content (10–19 mm in diameter) on selected soil physical properties, field soil thermal and water regimes, runoff and soil loss and potato yield and tuber quality on a sandy loam soil in New Brunswick. The objectives were to evaluate both beneficial and adverse effects of coarse fragment content (0, 10, 20 and 30% by volume) on soil quality in relation to potato production over a 4-yr period. Soil bulk density increased significantly by incorporating 10 to 30% coarse fragments into the plow layer. Porosity and available soil water-holding capacity were reduced in response to this increase in bulk density. In spite of the reduction in total porosity, pore size greater than 148 µm diameter of the 30% coarse fragment treatment was significantly greater than the 0, 10 and 20% treatments during 2001, 1 yr after the treatments were applied. This increase in macropores may have been responsible for the significantly higher saturated hydraulic conductivity of the soil treated with 30% coarse fragments. The results from 2002 and 2003 show that these beneficial effects on soil physical properties were short lived in this study; however, this may not be the case under field conditions because experimental plot problems of relocation of coarse fragments beyond plot boundaries and/or dilution with incorporation of stone-free subsoil material is not an issue in the field. Volumetric water content at field capacity of −33.3 kPa matric potential declined from 20.9% for the control to 7.7% for the 30% coarse fragment treatment. Cumulative soil heat greater than 10°C of the 30% treatment showed significant increases of 11.2, 8.8, and 3.7% during the growing season of 2001, 2002, and 2003, respectively, as compared with the control. Although field soil water tension regimes revealed that soil water in different treatments was held at a somewhat similar energy status, field soil water content was reduced considerably with increasing amount of coarse fragments. No significant differences in runoff and soil loss were found between treatments, but average reductions in soil loss over the 3-yr period were 9, 36, and 47% lower than the control for the 10, 20, and 30% treatments, respectively. Although no significant difference in yield and tuber quality between treatments was found in 2001–2003, both total and marketable yield decreased with increasing time. The yield reduction over time may be directly attributed to the mono-culture of potatoes practiced during the course of this experiment. Key words: Soil temperature, soil moisture, conductivity, bulk density, tillage erosion, potato cropping
Spatial and temporal trends in soil properties and crop yield at a site under intensive up- and down-slope potato production in northwestern New Brunswick
Authors: Rees H W , Chow T L , Gregorich E G
Published: April 2011

Few quantitative data are available to assess temporal changes in the soil quality of Canada’s agricultural lands. Site 20-NB was established in 1989 to monitor changes in an Orthic Humo-Ferric Podzol developed on coarse loamy till on a rolling landscape under intensive potato production in Atlantic Canada with soil compaction and water erosion the dominant forms of degradation. Sampling of soil and crop parameters was conducted on a 20 × 25 and 25 × 25 m grid basis with 66–90 sample locations. Baseline soil samples were collected in 1989 and the site was re-sampled in 1999. Samples were analysed for pH, available P, K, Ca and Mg, and total soil organic carbon (SOC). Field saturated hydraulic conductivity (Kfs) at 12–22, 27–37 and 50–60 cm, earthworm counts and crop yield measurements were conducted annually. 137Cs data were collected to estimate long-term soil erosion. Annual runoff (May 01 to Nov. 30) and soil loss were measured. Seasonal soil loss between 1989 and 1999 was only 6522 kg ha-1 yr-1 compared with 137Cs-estimated soil displacement of 53 000 kgha-1 yr-1, occurring over the 1960 to 1990 period. In the Ap horizon, soil pH and P increased by 8 and 5%, respectively, while SOC was reduced by 8%. Some changes were identified in the subsoil (50–65 cm) with a 7% increase in pH and a 27% reduction in P. There was little annual variation in the Kfs of the Ap, B and C horizons which ranged from 0.4 to 1.3, from 0.7 to 1.3 and from 0.8 to 2.0 cm h-1. Solum Kfs was significantly less than in an adjacent forested area by 52–80%. Earthworm numbers increased at a rate of 1.5 earthworms m-2 yr-1. Crop yield did not show any temporal trend over the 10-yr period other than that it appeared to be significantly influenced by crop rotation. Potato yield (CV = 12) tended to be less variable than barley (CV = 22) or clover (CV = 21). The benefits of site specific management were found to be questionable. 137Cs-estimated soil loss was most strongly related to SOC (r = −0.66) and average potato yield (r = −0.55). Key words: Soil quality, soil carbon, hydraulic conductivity, earthworms, water erosion
Aggregate slaking during rapid wetting: Hydrophobicity and pore occlusion
Authors: Zaher Hafida , Caron Jean
Published: April 2011

The slaking process after rapid wetting is a key factor controlling soil structural stability in dry soil, and an understanding of the relative importance of the different mechanisms involved in slaking may help in the design of management strategies aimed at maintaining a stable surface soil structure. Slaking has been linked to, among other factors, rapid pressure build-up in aggregate, and previous work has emphasized the role of organic matter to hamper that pressure build-up, possibly due to hydrophobicity, reducing rapid water entry within aggregates and hence the build-up. This study emphasizes this latter aspect linked to slaking. The evolution of the intra-aggregate pressure, the matter lost by slaking and the expelled air after rapid wetting of two soils of different textures (clay loam soil and silty-clay loam soil) amended with different types of paper sludge were studied. Hydrophobicity effects were also studied using a tensio-active solution. The results of these experiments showed that when aggregates were submitted to sudden wetting, those treated with paper sludge had an improved resistance to the destructive action of rapid wetting. The lower pressures measured in the aggregates from the amended soils and having less slaking resulted most likely from slow water entry and reduced swelling. Detailed investigation on the link between hydrophobicity and water entry revealed that the true hydrophobic effect (modification of contact angle) was non-existent for the silty-clay loam and minor for the clay loam. This study, rather, suggests that changes in the water potential at the wetting front following organic matter addition and aggregate immersion most likely depend on pore occlusion and on changes in pore surface roughness. Key words: Aggregate stability, organic matter, slaking, pressure, swelling, wettability
Nitrogen dynamics in floating and non-floating peatlands in the Western Boreal Plain
Authors: Wray H E , Bayley S E
Published: April 2011

The overall objective of this study was to measure the major nitrogen pools and fluxes in nutrient- and peat-rich, vegetated marshes and fens surrounding shallow ponds in the Western Boreal Plain (WBP) of Canada. Within the same peatland-pond complex, marshes and fens did not differ from each other in major N fluxes and pool sizes; however, significant differences in N dynamics were measured between different peatland-ponds. Specifically, N cycling rates (gross and net mineralization) were much greater in a floating peatland than in a non-floating peatland. Gross N mineralization rates were 59 and 453 mg N m-2 d-1 in the non-floating and floating peatlands, respectively. Gross ammonification rates were approximately 4–10 times net rates while gross nitrification rates were 500–800 times net rates, indicating rapid turnover of extractable inorganic N pools. Increased moisture and carbon in the floating peat supported higher microbial biomass and activity, however net primary production values were lower, presumably due to competition by microbes for available inorganic N. Monthly measurements of N fluxes were combined to provide an estimate of annual internal N cycling within marshes and fens surrounding shallow ponds in the WBP. Key words: Gross mineralization, microbial biomass, nitrogen, peatland
SimPLE.ca: Simulator of productivity loss due to erosion for Canada
Authors: Bremer E. , Greer K J , Black M. , Townley-Smith L. , Malhi S S , Izaurralde R C , Larney F J
Published: April 2011

Robust and practical estimates of the impact of soil erosion on crop productivity are essential for developing and implementing appropriate solutions for soil erosion on agricultural land. The objective of this study was to develop a simple model which captured the most important relationships between topsoil erosion and productivity loss for major agricultural regions of Canada. The model was developed for spring wheat (Triticum aestivum L.) and corn (Zea mays L.). Using annual time steps, maximum crop yields were reduced by soil erosion due to losses in available water-holding capacity, N-mineralization potential and available P. Using minimal input data, the model accounted for 56% of the variation in relative yields (fraction of non-eroded controls) determined in field studies using desurfacing or comparison plot methods. Key words: Available N and P, model, nutrients, productivity loss, simulator, soil erosion, soil properties, yield loss
Evaluation of phosphorus retention equations for Manitoba soils
Authors: Ige D V , Akinremi O O , Flaten D N
Published: April 2011

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 <7 than for soils with pH ≥7. The equations also worked better for soils with pH similar to those of the soils that were used to formulate the P retention equations. The accuracy of the predicted P sorption capacity improved with the manured soils due to the direct influence of manure application on soil properties that influence P retention such as Ca and Mg. Overall, the combination of CaM3, MgM3 and AlOx provided the best estimate of the PRC of Manitoba soils. Key words: Soil phosphorus, calcareous soils, phosphorus sorption, phosphorus retention, phosphorus retention capacity, estimating phosphorus retention capacity
Elution of inorganic and organic phosphorus from surface applied organic amendments
Authors: Idowu M K , Ige D V , Akinremi O O
Published: April 2011

Understanding the effects of organic amendments on the movement of organic and inorganic phosphorus (P) in soils is important for effective P management in agricultural soils. Thus, the effects of beef cattle manure, hog manure and biosolids on the downward movement of organic (Porg) and inorganic (Pi) P in Lakeland and Osborne soils were investigated. The amendments were added to the soils at the rate of 0, 200, 400 and 800 kg P ha-1 by mixing with the top 1 cm of soil in a column. The column was eluted with 20 pore volumes (PV) of 0.01 M CaCl2. The amount of total P (PT), Porg and Pi in the effluent was determined. The concentrations of Porg and Pi in the effluent increased as the rate of amendment application increased. A greater percentage of PT was lost as Pi in the soils amended with hog manure and biosolids, while in the soil amended with beef cattle manure, Porg constituted a greater portion of the total P eluted. As much as 63% of total P eluted from the Lakeland soil at the highest rate of beef cattle manure was in the form of Porg. Lakeland soil retained more Pi than the Osborne soil due to its greater P retention capacity. Organic P was lost within the 2nd and the 4th PV in the two soils, which illustrated the ease of Porg movement through the soil. In conclusion, both organic and inorganic P can move through the soil in organically amended soils and the risk of losing organic P by leaching is greater in soils amended with high rates of beef cattle manure. Key words: Biosolids, hog manure, beef cattle manure, elution, organic phosphorus, inorganic phosphorus
Soil organic carbon sequestration potential for Canadian Agricultural Ecoregions calculated using the Introductory Carbon Balance Model
Authors: Bolinder M A , Andrén O. , Kätterer T. , Parent L -E
Published: April 2011

The potential for storage of atmospheric CO2-C as soil organic C (SOC) in agroecosystems depends largely on soil biological activity and the quantity and quality of annual C inputs to soil. In this study we used the Introductory Carbon Balance Model (ICBM) approach driven by daily standard weather station data, specific soil properties and crop characteristics at the scale of Canadian agricultural ecoregions. The objectives were to calculate a climate-dependent soil biological activity parameter representative for annual agricultural crop production systems (re_crop) and to estimate the effect of fallow (re_fallow). These parameters are based on the daily product of soil temperature and stored water that influence biological activity in the arable layer, and are used to adjust the decomposition rates of the ICBM SOC pools. We also tested re_crop and re_fallow on SOC stock change data for different site and treatment combinations from long-term field experiments located in some of the ecoregions. An re_crop value of 0.95 for western ecoregions was on average 0.23 units lower than that of the eastern ecoregions, indicating a lower decomposition rate of SOC. Although the estimated annual C inputs to soil for small-grain cereals were on average ≈7.5% higher in the eastern ecoregions (305 vs. 285 g C m-2 yr-1), the overall results suggest that the western ecoregions would have a greater potential to maintain high SOC levels in the long term. However, these parameters varied between ecoregions and, consequently, the SOC sequestration potential was not always higher for the western ecoregions. The effect of fallow was on average ≈0.04, i.e., SOC decomposed slightly faster under fallow. Predictions for 24 out of 33 site and treatment combinations across Canada were significantly improved (P = 0.003), compared with a previous application with the ICBM that did not differentiate between crops and fallow. The methodology used here enabled us to examine regional differences in the potential for SOC sequestration as a balance between annual C inputs to soil and soil biological activity. Key words: Annual C inputs, climate, fallow, soil biological activity, agroecosystems
Soil resistance under grazed intermediate wheatgrass
Authors: Liebig M A , Hendrickson J R , Berdahl J D , Karn J F
Published: April 2011

Intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey subsp. intermedium] is a productive, high-quality perennial forage that lacks persistence under grazing. A study was conducted to evaluate the effects of three grazing times on soil bulk density, soil pH, and soil organic C under intermediate wheatgrass. Treatment effects on the three soil attributes were negligible, implying grazing time did not negatively impact intermediate wheatgrass beyond a threshold whereby critical soil functions were impaired. Findings from this study are important in the context of sustainable forage and cropping system management, where maintaining or improving critical soil functions are essential for enhancing agroecosystem sustainability. Key words: Seeded perennial forages, Northern Great Plains, soil organic C
Denitrification and ammonification at low soil temperatures
Authors: Dorland S. , Beauchamp E. G.
Published: April 2011

A laboratory study was conducted to determine the effects of temperatures from −2 to 25 °C on denitrification and ammonification in anaerobic soil treated with alfalfa or glucose. Organic C substrate as alfalfa or glucose increased denitrification rates at all temperatures within this range and lowered the threshold temperature at which denitrification occurred. The threshold temperature for denitrification was as low as −2 °C in unfrozen (supercooled) soil in contrast to most other studies where the threshold temperature was reported to be at or above 0 °C. When soil was frozen at −2 °C, the denitrification rate was much lower than in unfrozen soil at the same temperature. A square root model was employed which showed that the square root of the denitrification rate was linearly related to temperature from −2 to 25 °C. The maximum amount of [Formula: see text] produced during the incubation periods generally decreased from −2 to 25 °C and was greatest when glucose and especially alfalfa were added. The rate of ammonification increased with addition of alfalfa but the quantities of [Formula: see text] produced generally decreased from 25 to −2 °C. Key words: Threshold temperature, frozen vs. unfrozen soil, nitrite production, square root model
Effect of crop rotations and cultural practices on soil organic matter, microbial biomass and respiration in a thin Black Chernozem
Authors: Campbell C. A. , Biederbeck V. O. , Zentner R. P. , Lafond G. P.
Published: April 2011

The effects of crop rotations and various cultural practices on soil organic matter quantity and quality in a Rego, Black Chernozem with a thin A horizon were determined in a long-term study at Indian Head, Saskatchewan. Variables examined included: fertilization, cropping frequency, green manuring, and inclusion of grass-legume hay crop in predominantly spring wheat (Triticum aestivum L.) production systems. Generally, fertilizer increased soil organic C and microbial biomass in continuous wheat cropping but not in fallow-wheat or fallow-wheat-wheat rotations. Soil organic C, C mineralization (respiration) and microbial biomass C and N increased (especially in the 7.5- to 15-cm depth) with increasing frequency of cropping and with the inclusion of legumes as green manure or hay crop in the rotation. The influence of treatments on soil microbial biomass C (BC) was less pronounced than on microbial biomass N. Carbon mineralization was a good index for delineating treatment effects. Analysis of the microbial biomass C/N ratio indicated that the microbial suite may have been modified by the treatments that increased soil organic matter significantly. The treatments had no effect on specific respiratory activity (CO2-C/BC). However, it appeared that the microbial activity, in terms of respiration, was greater for systems with smaller microbial biomass. Changes in amount and quality of the soil organic matter were associated with estimated amount and C and N content of plant residues returned to the soil. Key words: Specific respiratory activity, crop residues, soil quality, crop rotations
Characterizing the soil physical condition in reduced tillage systems for winter wheat on a fine sandy loam using small cores
Authors: Carter M. R.
Published: April 2011

A tillage study was conducted in Prince Edward Island with winter wheat (Triticum aestivum L.) over two seasons on a Gowanbrae light fine sandy loam, a Humo-Ferric Podzol. One-pass mouldboard ploughing, shallow tillage using a rotary harrow, and direct drilling were evaluated for their effects on crop productivity and soil physical properties. Direct drilling increased plant survival but not grain yield in the first year compared to the other tillage systems. Leaf diseases significantly reduced crop performance under shallow tillage and direct drilling in the second year. None of the tillage systems had adverse effects on soil strength at field capacity over the 0- to 350-mm soil profile depth, as penetrometer resistance values were < 1.5 MPa. Differences in soil macro-aggregation and organic carbon distribution between tillage systems were noted in the Ap horizon. Sequential measurements on soil cores equilibrated at 6 kPa tension for macropore volume, air permeability at low air pressure (0.25 kPa), oxygen diffusion rate (ODR) at 0.65 mV, and shear strength indicated that the soil physical condition was within the optimum range for root growth, over the 0- to 240-mm depth, in each tillage system. In addition, relative compaction was maintained at a low level in all systems. The quotient of air permeability and macropore volume, as an index of pore continuity, indicated that the relatively large macropore volumes under mouldboard ploughing were less efficient in conducting air than the macropores under direct drilling. These differences in pore continuity were most prevalent at the lower soil depth.Key words: Soil physical properties, soil compaction, Podzolic soil, winter cereals
Comparison of shrink-swell indices of some Saskatchewan soils and their relationships to standard soil characteristics
Authors: Jong E. De , Kozak L. M. , Storehouse H. B.
Published: April 2011

Shrink-swell indices for 27 soil samples (representing the major horizons of eight soil profiles) were determined and related to soil texture, organic and inorganic C content, and specific surface area. The coefficient of linear extension was measured from saturation and from 33 kPa matric suction to oven-dryness on undisturbed clods (COLEclod) and on remolded samples of the less than 2-mm fraction (COLErod); the Atterberg limits were determined on the less than 0.4-mm fraction. COLEclod, COLErod and the plasticity index were highly correlated with each other and with clay content and surface area, but not with organic or inorganic C. The extent of the shrinkage was significantly (P > 0.01) related to the water content at the start of the shrinkage test; this relationship was clearer for the remolded than the undisturbed samples, possibly due to the structure of the clods. Key words: Coefficient of linear extension, plasticity index, clods vs. remolded, texture, organic carbon
Episodic fluxes of methane from subarctic fens
Authors: Windsor J. , Moore T. R. , Roulet N. T.
Published: April 2011

Measurements of methane flux from northern peatlands to the atmosphere are complicated by high spatial and temporal variability. We quantified the variability of methane flux from two subarctic fens near Schefferville, northern Quebec, using a static chamber technique. Within the seasonal pattern of increasing fluxes associated with the warming of the peat profile, episodic fluxes of methane were observed. One set of episodic events occurred during the spring thaw of the upper layers of the peat, which released methane stored in ice over the winter. The second set, generally of short duration (< 2 d), occurred in mid-summer and appeared to be related primarily to the lowering of the water table. In four of six subjectively-identified, episodic fluxes during the 1990 summer the flux during the episodic event was equal to or greater than the upper 95% confidence level of the three fluxes before and after the event (t-statistic probabilities ranged from < 0.001 to 0.038). Mechanisms to account for these episodic fluxes of methane include increased methane diffusivity, removal of overburden pressure and reduced rates of methane consumption in the surface layers of the peat. Omission of these episodic fluxes could lower estimates of seasonal methane emissions by 7–22%. Key words: Peatlands, fens, methane
Spatial redistribution of Cs-137 and soil erosion on Orléans Island, Québec
Authors: Bernard Claude , Laverdière Marc R.
Published: April 2011

Cs-137 redistribution data have been used to estimate the extent and the pattern of long-term soil erosion in the Québec City area. Mean annual net soil movements ranging from a deposition of 10.8 t ha−1 yr−1 to a loss of 31.8 t ha−1 yr−1 were estimated. The slope steepness and the land use significantly influenced the estimated rates of soil movement, while soil texture was less important, probably because of the soils’ sandy texture or the high content of organic carbon, which kept their erodibility low. The net soil losses estimated from Cs-137 data were consistently higher than those predicted by the USLE. Besides net soil losses, it was possible to estimate separately the magnitude of soil detachment and soil deposition. Two–thirds of the stations sampled experienced net soil loss while the remaining third showed evidence of soil accumulation. These data suggest that the small net soil losses measured for low erosive conditions (flat slopes, dairy farming) result from important soil redeposition rates as much as from small soil detachment rates. Cs-137 redistribution data not only produce reliable estimates of soil movement rates, but also allow enhanced estimates of the agronomic and environmental impacts of soil erosion.Key words: Cs-137, erosion, sedimentation, USLE, sediment delivery ratio
Long-term effects of orchard soil management on tree vigor and extractable soil nutrients
Authors: Neilsen G. H. , Hogue E. J.
Published: April 2011

Bisbee Delicious apple trees on M.26 (Malus domestica Borkh.) rootstock were planted in 1982 on a neutral pH, loamy-sand soil and were subjected to five soil management-fertilizer regimes until 1989. Orchard floor vegetation control with herbicides was required to maximize tree growth. Annual application of P at 50 kg ha−1 and K at 100 kg ha−1 from 1984 to 1989 increased extractable soil P and K to the 40-cm depth but did not appear to increase tree vigor. Orchard floor vegetation maintained extractable soil Ca and Mg levels compared to vegetation control treatments. Key words: Orchard floor vegetation management, extractable soil P, K, Ca and Mg
Soil organic-carbon dynamics after 80 years of cropping a Dark Brown Chernozem
Authors: Monreal C. M. , Janzen H. H.
Published: April 2011

The temporal change of soil organic-carbon (Corg) was studied in soil samples taken from long-term crop rotations at Lethbridge. Between 1910 and 1990, net Corg losses for the 0–15 cm depth varied between 23% under fallow–wheat (FW) and 21% under fallow–wheat–wheat (FWW) and 17% under continuous wheat (W). Analysis of variance and an LSD test indicated that in 1990 the surface Corg concentrations were similar among all crop rotations. Corg in the 15–30 cm depth decreased over time and was significantly lower than in surface samples. Key words: Organic carbon, dry combustion, cold-wet dichromate digestion
Effects of drip fertigation of NH4-N and P on soil pH and cation leaching
Authors: Parchomchuk P. , Neilsen G. H. , Hogue E. J.
Published: April 2011

Mixtures of ammonium nitrate and ammonium polyphosphate fertilizers were used to drip fertigate Summerland McIntosh apple trees (Malus domestica Borkh.) grown on M.9 rootstocks in gravelly sandy loam. Levels of N corresponding to 25 and 50% of the recommended broadcast rate (23.5 and 47.0 g tree−1, respectively) and three levels of P (0, 17.5 and 35.0 g tree−1) were applied in a factorial randomized complete block design. Soil acidification began within 1 yr in a zone extending approximately 60 cm vertically and horizontally from the drip source. Acidification was most severe at 20–30 cm directly beneath the emitter where the soil pH decreased from 5.8 to 4.5 after 1 yr and to 3.7 after three seasons of fertigation. Rate and magnitude of pH decline were equal for both rates of N and acidification was not enhanced by the simultaneous addition of P. Calcium, Mg and K were leached to the periphery of the acidified zone. The rapid displacement of K may be of concern, particularly when NH4 forms of N are drip-fertigated in coarse-textured soils with marginal K levels. Key words: Fertigation, soil acidification, cation leaching, nitrogen fertilizer
Effects of selected agrochemicals on methane oxidation by an organic agricultural soil
Authors: Topp Edward
Published: April 2011

Methane oxidation by soils is an important sink for this greenhouse gas. When tested at 50 mg L−1, the herbicide bromoxynil, the insecticide methomyl, and the nitrification inhibitor nitrapyrin inhibited methane oxidation by soil slurries. The results suggest that these chemicals might decrease methane oxidation by agricultural soils. Key words: Soil methane oxidation, inhibition, agrochemicals
Distinction of soil thermal regimes under various experimental vegetation covers
Authors: Balisky Allen C. , Burton Philip J.
Published: April 2011

Five vegetation treatments were established in 1.2 m × 1.2 m plots in 1990: (1) bare mineral soil, (2) Epilobium angustifolium, (3) Rubus spectobilis, (4) Alnus rubra and (5) a mixture of all three species. Soil temperatures were measured at 10-cm depths in three replicates of each treatment during the early summer of 1991. Mean, maximum and minimum temperatures always exhibited the same rank order of treatments — bare > Epilobium > Rubus > mixture > Alnus — but the latter four treatments were not readily distinguishable. A data-adjustment procedure based on Fourier analysis was conducted and its utility discussed for use in the separation of treatment effects where observations exhibit a detectable diurnal cycle. Using this method, the soil thermal regime of the Epilobium treatment was demonstrated to be statistically distinct from that of the bare plots and from those of the other vegetation treatments. Key words: Fourier analysis, diurnal pattern, soil temperature, vegetation effects, microclimate
Salinity and nutrient distribution in soil profiles of long-term crop rotations
Authors: Beke G. J. , Janzen H. H. , Entz T.
Published: April 2011

The effect of cropping systems on salt and nutrient movement in soil has been studied mainly at relatively short-term (< 20 yr) experimental sites or at commercial sites without documented history. This study investigated the impact of two similar, unfertilized, long-term crop rotation experiments, differing in duration and experimental design, on soil EC (salinity), sodium adsorption ratio (SAR), nitrate-N, and extractable-P distributions in semi-arid southern Alberta. The experiments, established in 1911 and 1951 at the Lethbridge Research Station on moderately well drained soils, included continuous spring wheat (Triticum aestivum L.) fallow-wheat-wheat and fallow-wheat cropping sequences. Regardless of length of experiment or cropping sequence, the salinity and SAR values increased with soil depth. Leaching of salts had occurred to a minimum depth of 150 cm, depending on the nature of the parent material and soil-drainage volumes. Within the 90- to 150-cm depth, most salt leaching had taken place under the fallow-wheat rotation and least under the continuous-wheat cropping sequence. Downward movement of nitrate-N generally peaked in the lower root zone, regardless of cropping system or duration of the experiment. Deep leaching of nitrate-N had occurred in the fallow-wheat soil. Movement of extractable P was restricted to the 0- to 30-cm depth. Significant deep leaching of salts had taken place over the 35-yr period of the 1951 experiment whereas the longer, 75-yr period of the 1911 experiment was required to cause significant deep leaching of nitrate-N and of extractable P movement in the 0- to 30-cm depth. Key words: Dryland crop rotations, summerfallow, semi-arid region, soil salinity, soil nitrate and phosphate
Exchangeable cations and cation exchange capacity of forest soil samples: Effects of drying, storage, and horizon
Authors: Meyer Wietse L. , Arp Paul A.
Published: April 2011

Concentrations of Ca, Mg, K, Na, Al, Fe, Mn, and Si extractable with 1 N ammonium chloride (NH4Cl, pH 4.5) and 1 N ammonium acetate (NH4OAc, pH 4.5) were determined for forest soil samples as follows: (1) before drying, and (2) at several time intervals after air-drying (1, 5, 11 and 14 wk). Values for CEC were obtained for the same samples by determining (1) the sum of cations (Al3+, Ca2+, Mg2+, K+, Na+, Fe3+, and Mn2+) in the extracts [denoted [Formula: see text] and [Formula: see text]], and (2) the amount of ammonium retained by the soil samples against water washing [denoted CEC(NH4OAc) and CEC (NH4Cl)]. The soils used in this investigation were taken from four New Brunswick upland forest sites (two sugar maple sites, one mixed wood site, and one spruce site). It was round that (1) extractable Mg, K, Na, and Mn levels were generally not affected by drying, storing, and type of extradant; (2) extractable Al and Fe levels increased immediately after drying; (3) NH4OAc-extracted Al, Fe, and Si exceeded NH4Cl-extracted Al, Fe, and Si; (4) extracted Al and Fe levels tended to drop after 11 wk of storage; (5) small drying effects were also noticed for NH4Cl-extracted Ca; (6) CEC(NH4OAc) and CEC(NH4Cl) values decreased with increasing time of storage; this effect was noticed most for soil samples with high levels of organic matter (Ah, Ahe, Bm, Bf, and Bfh), and was noticed least for sod samples taken from leached horizons (Ae) and subsoil horizons (BC and C); (7) in some cases, storage time increased CEC(NH4OAc) in subsoils; (8) values for [Formula: see text] remained fairly independent or increased slightly with storage time and were closely related with CEC(NH4Cl) values obtained with non-dried samples; (9) values for [Formula: see text] did not relate well with CEC(NH4OAc) and CEC(NH4Cl). Differences for extractable Al were likely due to Al complexation by acetate ions. Drying effects on extractable Al and Fe (and possibly Ca) were likely due to drying-induced fragmentation of soil organic matter. Drying and storage effects on CEC(NH4OAc) and CEC(NH4Cl) were likely due to (1) water-washing and related loss of organic matter, and (2) sensitivity of subsoil minerals to air exposure. Apparent drying and storage effects on CEC were most noted with [Formula: see text] and were least noted with [Formula: see text]. Key words: Cation exchange capacity, ion exchange, drying, storage, ammonium acetate, ammonium chloride extractions
Effect of cultivar on response of wheat and barley to chloride fertilization
Authors: Mohr R. M. , Bernier C. C. , Flaten D. N. , Racz G. J.
Published: April 2011

Crop cultivar has been shown to affect the frequency and magnitude of yield responses to chloride (Cl−) fertilizer applications. Information regarding the Cl− responsiveness of cereal cultivars commonly grown in western Canada is limited, however. Field experiments were conducted in Manitoba in 1990 and 1991 to determine the effect of Cl− fertilization on plant nutrient status, grain yield and grain quality of Katepwa, Roblin, Biggar and Marshall wheat (Triticum aestivum L.) and of Bedford, Brier, Argyle and Heartland barley (Hordeum vulgare L.). Chloride fertilization increased the concentration of Cl− in plant tissue of all cultivars. Increased grain yield and improved grain quality due to Cl− fertilization occurred more frequently in wheat than in barley; however, cultivars within a species differed in Cl− responsiveness. The application of 50 kg Cl− ha−1 significantly increased grain yield for Heartland barley by 905 kg ha−1 in one of four experiments, for Roblin wheat by 492 kg ha−1 in one of four experiments, for Biggar wheat by an average 333 kg ha−1 in two of four experiments and for Marshall wheat by an average 363 kg ha−1 in two of four experiments. However, the application of 50 kg Cl− ha−1 resulted in significant reduction in grain yield for Bedford in one of four experiments and for Marshall in one of four experiments. Yield responses to Cl− were not related to soil Cl− content or Cl− concentration in plant tissue. Key words: Chloride, fertilizers, wheat, barley, cultivars, yield
Gamma radioactivity on a chronosequence, Pinery Provincial Park, Ontario
Authors: VandenBygaart A. J. , Protz R.
Published: April 2011

Natural gamma-emitting radionuclide distributions in soils along a time sequence on dune materials in Ontario were studied. 226Ra, 232Th and 40K showed distributions influenced by soil processes and their genesis. Chronofunctions were formulated relating gamma radioisotope properties within soil horizons to the ages of the soils. 40K tended to increase in relative concentration in the upper solum as compared with the Ck likely due to carbonate mineral weathering and removal. 226Ra and 232Th tended to accumulate in the B horizons possibly associated with sorption onto Fe-oxide and clay surfaces. However, more 232Th was retained in the solum relative to 226Ra due to the immobility of 232Th. Thus the 232Th/226Ra ratio holds potential for use in studies of soil weathering. The apparent accumulation of 232Th and 226Ra within the solum during 4700 yr of soil development and weathering suggests that these radioisotopes may remain within the soil profile for long periods. Key words: Radioisotope, radionuclide, soil genesis, 40K, 226Ra, 232Th, 137Cs
Turnover of soil organic matter and storage of corn residue carbon estimated from natural 13C abundance
Authors: Gregorich E. G. , Monreal C. M. , Ellert B. H.
Published: April 2011

Total organic C and natural C abundance were measured in a forest soil and a soil under corn (Zea mays L.) to assess management-induced changes in the quantity and initial source of organic matter. The total mass of organic C in the cultivated soil was 19% lower than in the forest soil. It was estimated that after 25 yr of continuous corn, 100 Mg C ha−1 was returned to the soil as residues, of which only 23 Mg ha−1 remained in the soil; 88% of the remaining corn-derived C (C4-derived C) was in the plow layer. About 30% of the soil organic C in the plow layer (0–27 cm) was derived from corn. Assuming first order kinetics, the half-life of C3-derived C in the 0- to 15-cm layer was 13 yr. The half-life of C3-derived C in the 0- to 30-cm layer, which included organic C below the plow layer, was 24 yr. Mineralization of the light fraction (LF) was faster than that of organic matter associated with particle-size fractions. More than 70% of the LF had turned over since the start of corn cropping, and 45% of organic matter in the sand fraction comprised corn residue. The half-life of C3-derived C in the LF was 8 yr. The mineralization of C from native organic matter associated with the coarse silt fraction was the slowest of all particle-size fractions. Key words: Soil organic matter, carbon storage, natural 13C abundance, light fraction, particle-size fractions, mineralization
Effects of ammonium lignosulphonate and diammonium phosphate on soil organic carbon, soil phosphorous fractions and phosphorous uptake by corn
Authors: Fyles J. W. , Xie X. H. , MacKenzie A. F. , O’Halloran I. P. , Xie R. J.
Published: April 2011

Low P fertilizer efficiency can be attributed to a reduction in solubility due to P reactions with soil components. Added organic material may reduce such reactions and improve P fertilizer efficiency. Lignosulphonate (LS), a by-product of the pulp and paper industry, could have beneficial effects on fertilizer P. Effects of ammonium lignosulphonate (ALS) and diammonium phosphate (DAP) on corn (Zea mays L.) P uptake, extractable P and P fractions were measured. Soil P fractions were determined using a field incubation technique to simulate banded P applications in two Humic Gleysols, a Ste. Rosalie clay soil and an Ormstown silty clay loam soil. Soil organic C increased with increasing ALS addition and decreased with DAP additions. ALS had little effect on native soil P fractions. When applied with DAP, increasing rates of ALS increased Mehlich-III extractable P, 0.5 M NaHCO3 and 0.1 M NaOH extractable inorganic P, reduced 1.0 M HCl extractable P and had no effect on organic P extractable in 0.5 NaHCO3 and 0.1 M NaOH. Applying ALS at rates up to 300 kg ha−1 with P at 60 kg P2O5 ha−1 may improve uptake by corn of fertilizer P, but using ALS alone does not improve native soil P availability. Key words: Lignosulphonate, phosphorous fractions, field incubation, organic carbon, Zea mays L.
SHORT COMMUNICATION: A comparison of plant tissue digestion methods for nitrogen and phosphorus analyses
Authors: Soon Y. K. , Kalra Y. P.
Published: April 2011

Four variations of the Kjeldahl digestion were compared with a H2SO4–H2O2 digestion for N and P analysis, and a microwve digestion method and a dry ashing procedure for P analysis. One Kjeldahl variant using a Na2SO4–Se catalyst was found to be suitable for multi-element analysis while doubling the per diem output of digestions compared with the H2SO4–H2O2 method, provided that P was analyzed by the molybdivanadate (MV) procedure. Key words: Kjeldahl digestion, nitrogen, phosphorus, plant tissue